A Comparison of Red Fox (Vulpes Vulpes) and Feral Cat (Felis Catus) Diets in the South West Region of Western Australia

Home , Cat, Felis, Mammals of Australia, Red foxes in Australia

A comparison of red fox (Vulpes vulpes) and feral cat (Felis catus) diets in the south west region of Western Australia

Submitted by

Heather Crawford BSc (Zoology)

This thesis is presented as part of the requirement for the degree of Bachelor of Science Conservation and Wildlife Biology with Honours at Murdoch University.

Word Count: 27, 880

School of Biological Sciences and Biotechnology

H1150 Honours Thesis in Conservation and Wildlife Biology

November, 2010

Supervisors: Dr Patricia Fleming: School of Veterinary and Biomedical Sciences

Associate Professor Mike Calver: School of Biological Sciences and Biotechnology

Dr Peter Adams: School of Veterinary and Biomedical Science Declaration

I, Heather Crawford, declare that this Honours thesis is my own account of my research into the diets of red foxes and feral cats in south west western Australia. No part of my thesis has been previously submitted for a degree at any tertiary educational institution.

Signed

Heather Crawford

Date:

i Acknowledgements

Firstly I would like to thank my supervisors, Dr Trish Fleming, Associate Professor Mike Calver and Dr

Peter Adams. Thank you for developing a project that pushed me to the limit and challenged me to

dig deep and find the energy and strength to cut up hundreds of foxes and work harder, mentally,

then I have ever worked before. Thank you Shannon, Trish and Peter for organising the collection

and processing of foxes across the south west region, and for your help preparing and examining

hundreds of hair samples! Thank you Mike, for all of your invaluable advice and patience with me

throughout the year. I would also like to thank Shannon Dundas, without whom there would be no

project on fox diets in the south west (sorry I did not find any quokka remains in the fox stomachs!).

My sincere thanks to all of the people who helped me collect and process data throughout my

project, this thesis would not have been possible without your help. Thank you to the volunteers

who helped us to chop up foxes which is not a task for the faint hearted! Thank you to all of the

farmers and hunters who provided us with carcasses and an insight into fox impacts in the south

west. To the organisers of the Red Card for Red Fox programme, thank you for working with ‘the fox team’ this year and for allowing us to turn your fields and barns into a blood bath!

A special thank you goes to Eddie Juras for suppling foxes caught in Williams, as well as giving me the opportunity to learn more about fox behaviour by introducing me to lovely little Eric. Thank you also to Paul de Tores, for suppling fox and cat carcasses from Leschenault Peninsula and Dwellingup. To

Claire Stevenson and Brad Maryan from the Western Australian Museum, and Mike Craig from

Murdoch University, without your expertise it would have taken me months to classify the hundreds of bird, reptile and amphibian samples, so thank you!!

A very special thank you must go to my wonderful family. Thank you dad, for taking photographs of my gory lab work and all of your encouragement. Thank you mom, for all of your emotional support

ii and love throughout the year. Thank you Brian for your artistic input, it has added another dimension to my thesis. Thank you Ross for all of your encouragement. Thank you to my pets (new and old), for keeping me sane this year.

And finally, I would like to thank Narelle Dybing and Jesse Forbes Harper who worked tirelessly by my side throughout the year, always finding an amusing side to slicing and dicing so many extremely pungent animals.

iii Abstract

There is a paucity of data on the diet of red foxes (Vulpes vulpes) and feral cats (Felis catus) in the south west region of Western Australia. Information is needed to determine the impact of these introduced predators on native wildlife, and to establish whether competitive and predatory interactions are likely to exist between foxes and cats. Therefore the diets of both species were quantified and compared by examining the stomach contents of 542 foxes and 56 cats collected from across the south west region in association with the Red Card for the Red Fox community feral control program. This study provides the first insight into the summer dietary preferences of the red fox and feral cat in south west Western Australia.

This study provided a ‘snapshot’ of dietary intake, revealing that there was little overlap in the diets of red foxes and feral cats (26%), with the proportions of different prey categories consumed differing significantly between the predators (ANOSIM- R=0.1352, p<0.0001). Overall, foxes consumed mostly domestic sheep as carrion or lamb (64%, using Index of Relative Importance values for this food category), as well as a large amount of fruit, grains and invertebrates. With numerous bird species as their staple prey (32%, by IRI), feral cats are actively hunting a greater proportion of native vertebrate species (43%, by IRI), than foxes (6%, by IRI). Surprisingly, cats deliberately consumed a large amount of plant material (18%, by IRI), which may suggest that this atypical food source plays a role in sustaining feral cats during summer.

From analysis of fox and cat diets it can be surmised that in the south west, interspecific competition between the predators may not be strong because of their reliance on different food categories.

However, removal experiments and investigation of spatial interactions between the two species are

iv required to confirm that resource partitioning and not antagonistic interactions are causing dietary differences (e.g. interference competition).

Findings from the current study into the diets of red foxes and feral cats have implications for both farmers and conservationists in the south west. If carrion is responsible for sustaining large fox populations (hyperpredation) during a period of reduced resources, removal of carrion may reduce fox population sizes substantially. If, however, active control of foxes then leads to mesopredator release, feral cats may have a greater impact on the south west’s remaining native species, especially if cats have increased access to carrion.

Contents

Declaration ...... i

Acknowledgements ...... ii

Abstract ...... iv

Chapter 1 General Introduction and Thesis Overview ...... 1

General Introduction...... 1

Thesis Overview ...... 2

Chapter 2 Literature Review ...... 3

History of Feral Predator Introductions in Australia ...... 3

The Red Fox ...... 6

The Feral Cat ...... 8

Diet of the Red Fox and Feral Cat in Australia ...... 10

Red Fox ...... 11

Feral Cat ...... 22

Foxes and Cats ...... 22

Chapter 3 General Methods ...... 24

Techniques for Quantifying Diets ...... 24

Study Sites ...... 25

Swan Coastal Plain Bioregion ...... 28

Jarrah Forest Bioregion ...... 28

Avon Wheatbelt Bioregion ...... 29

Sample Collection ...... 30

Dissections ...... 32

Stomach Processing ...... 35

Identification of Stomach Contents ...... 36

Food Categories ...... 38

vi Chapter 4 Does Dietary Competition Exist Between Foxes and Cats? ...... 40

Introduction ...... 40

Thesis Aims ...... 44

Methods ...... 45

Representativeness of Samples ...... 45

Quantifying Fox and Cat Diets ...... 45

Results ...... 50

Representativeness of Samples ...... 50

Quantifying Predator Diets ...... 51

Chapter 5 Discussion ...... 72

Overview and Interpretation of Principal Findings ...... 72

1) Describe the diet of foxes and cats at four sample sites across the south west of Western Australia ...... 72

2) Compare the diets of red foxes and feral cats, and explain any similarities or differences ..... 84

3) Interpret the dietary results in terms of hyperpredation ...... 88

4) Interpret the results in terms of mesopredator release by testing the following predictions: i) there is an overlap in fox and cat diets; ii) there is evidence of intraguild predation ...... 89

5) Discuss the likely impact on native West Australian fauna ...... 91

General Conclusions and Future Recommendations ...... 93

Chapter 6 References ...... 95

Appendices ...... 107

Appendix 1 – Feral Species Collection Card ...... 107

Appendix 2 – Diagram of Subjective Body Condition Scores ...... 108

Appendix 3 – List of Fauna Species Identified at Four Sample Sites ...... 109

Table of figures

Figure 2.1 Map of Australia depicting the distribution of red foxes...... 5

Figure 2.2 Map of Australia depicting the distribution of feral domestic cats...... 5

Figure 2.3 Map of Australia showing the number of published dietary studies conducted in each state and territory for red foxes...... 13

vii Figure 2.4 Map of Australia showing the number of published dietary studies conducted in each state and territory for feral cats...... 13

Figure 3.1 IBRA bioregions of south west Western Australia showing collection sites...... 26

Figure 3.2 Photograph of red fox dissection showing first stages...... 33

Figure 3.3 Photograph of red fox dissection showing second stages (sample stomach)...... 33

Figure 3.4 Photograph of a red fox’s stomach contents...... 34

Figure 3.5 Graphic of processing foods on sieve...... 34

Figure 4.1 Venn diagram indicating a small overlap in the dietary items consumed by the red fox and feral cat...... 41

Figure 4.2 Venn diagram indicating a large overlap in the7dietary items consumed by the red fox and feral cat...... 41

Figure 4.3 Accumulation curves of dietary categories for red foxes at Darkan (n=161)...... 53

Figure 4.4 Accumulation curves of dietary categories for red foxes at Katanning (n=113)...... 53

Figure 4.5 Accumulation curves of dietary categories for red foxes at Mount Barker (n=54)...... 53

Figure 4.6 Accumulation curves of dietary categories for red foxes at Boyup Brook (n=57)...... 53

Figure 4.7 Accumulation curves of dietary categories for feral cats at Darkan (n=6)...... 54

Figure 4.8 Accumulation curves of dietary categories for feral cats at Katanning (n=11)...... 54

Figure 4.9 Accumulation curves of dietary categories for feral cats at Mount Barker (n=7)...... 54

Figure 4.10 Accumulation curves of dietary categories for feral cats at Boyup Brook (n=15)...... 54

Figure 4.11 Body condition scores of red foxes from four sample sites...... 58

Figure 4.12 Multi-Dimensional Scaling figure showing overlap in the diets of red foxes from four sample sites...... 59

Figure 4.13 Pie chart of IRI values for the 15 food categories eaten by red foxes at Katanning. .... 61

Figure 4.14 Pie chart of IRI values for the 15 food categories eaten by red foxes at Darkan...... 61

Figure 4.15 Pie chart of IRI values for the 15 food categories eaten by red foxes at Mount Barker...... 62

Figure 4.16 Pie chart of IRI values for the 15 food categories eaten by red foxes at Boyup Brook. 62

Figure 4.17 Body condition scores of feral cats from four sample sites...... 65

Figure 4.18 Multi-Dimensional Scaling figure overlap in diets of feral cats from four sample sites...... 66

viii Figure 4.19 Pie chart of IRI values for the 15 food categories eaten by feral cats at Darkan...... 68

Figure 4.20 Pie chart of IRI values for the 15 food categories eaten by feral cats at Katanning...... 68

Figure 4.21 Pie chart of IRI values for the 15 food categories eaten by feral cats at Mount Barker...... 69

Figure 4.22 Pie chart of IRI values for the 15 food categories eaten by feral cats at Boyup Brook. 69

Figure 4.23 Pie chart of red fox diet proportions overall, calculated from average IRI values...... 70

Figure 4.24 Pie chart of feral cat diet proportions overall, calculated from average IRI values...... 70

Table of tables

Table 2.1 Thirty-six dietary studies of the red fox across Australia...... 14

Table 2.2 Eighteen dietary studies of the feral cat across Australia...... 19

Table 3.1 Land area of three of south west Western Australia's IBRA bioregions...... 26

Table 3.2 Top ten threatening processes to ecosystems south west Western Australia...... 27

Table 3.3 Conservation status of organisms in the three sample site bioregions...... 27

Table 3.4 Number of red foxes and feral cats collected from 12 sample sites across three bioregions...... 31

Table 3.5 The total number of fox and cat stomachs collected from four sample sites in south west Western Australia, and the total number of stomachs statistically analysed...... 31

Table 4.1 Average values of percentage surface area, frequency of occurrence, and Index of Relative Importance, for each dietary category of red foxes and feral cats...... 55

Table 4.2 Spearman’s rank correlation coefficient tests percentage surface area against IRI values for foxes and cats...... 56

Table 4.3 Spearman’s rank correlation coefficient tests average IRI values for red foxes against IRI values for feral cats...... 56

Table 4.4 Dietary overlap between red foxes and feral cats at four sample sites...... 57

Table 4.5 Body condition scores of red foxes and feral cats at four sample sites...... 58

Table 4.6 P-value: Analysis of similarity test results for red foxes at four sample sites...... 60

Table 4.7 R value: Analysis of similarity test results for red foxes at four sample sites...... 60

Table 4.8 Body condition scores of feral cats from four sample sites...... 65

Table 4.9 P-value: Analysis of similarity test results for feral cats at four sample sites...... 67

ix Table 4.10 R value: Analysis of similarity test results for feral cats at four sample sites...... 67

Table 4.11 P-value: Analysis of similarity test results for red foxes and feral cats at four sample sites...... 71

Table 4.12 R value: Analysis of similarity test results for red foxes and feral cats at four sample sites...... 71

x Chapter 1 General Introduction and Thesis Overview General Introduction Both the red fox (Vulpes vulpes) and feral domestic cat (Felis catus) occur in most Australian habitats. The impact that Australia’s two most recently introduced mammalian predators have had

on native wildlife is believed to be substantial, in some cases even driving native species to

extinction (Dickman, 1996a; Glen and Dickman, 2005). Lethal control of the red fox and feral cat is

actively carried out in Australia, especially in rural areas (Burrows et al., 2003; Saunders et al., 1995;

Sergio and Hiraldo, 2008). Red foxes and feral cats were selected as the species of interest for this

study as carcasses were readily available and because there is little information on the animals’ diets

in south west Western Australia.

The south west region of Western Australia is recognised as one of the earth’s 25 biodiversity

hotspots, containing some of the highest densities of endemic or range-restricted species and which are threatened by widespread habitat destruction (Australian Government Department of the

Environment, 2009; Brooks et al., 2002; Halse et al., 2004; Myers et al., 2000). The concern of the conservation community is that the constant removal of foxes from the Australian environment may result in an increase in feral cat numbers which could have a greater impact on native wildlife than foxes (Glen and Dickman, 2005). For this reason it is imperative that the degree of competition between red foxes and feral cats be established and the potential release of one species be assessed

(Glen and Dickman, 2005). To this end, the stomachs of 542 fox and 56 feral cats were collected from rural areas across the south west region of Western Australia in association with the Red Card for Red Fox Programme, co-ordinated by the Department of Agriculture and Food Western Australia

(Rondganger, 2010). Stomach contents were examined, classified and compared across and between species in order to establish the degree of overlap in fox and cat diets.

1 Thesis Overview The thesis begins with a literature review which examines the previous work carried out on the

biology of foxes and cats and their introduction into Australia.

In the second chapter, previous research into the diet of red fox and feral cats are reviewed and the findings summarised.

The third chapter details the collection site locations and the methods used to collect, process and statistically analyse stomach contents.

The fourth chapter begins with a brief introduction to competition theory and then specifies the main aims of the thesis. The methods used to assess these aims will be described, and the chapter will conclude with discussion of the results in the context of mesopredator release and hyperpredation in south west Western Australia.

The fifth chapter outlines the general findings and conclusions of this study.

2 Chapter 2 Literature Review History of Feral Predator Introductions in Australia Fauna extinctions have increased exponentially since European settlement of Australia in 1788

(Burbidge and McKenzie, 1989; Jupp, 2001; McKenzie et al., 2007; Short and Smith, 1994; Smith and

Quin, 1996). One of the human-mediated issues facing the Australian fauna has been the

introduction of exotic plant and animal species which have had deleterious effects on the native

flora and fauna of Australia (Burbidge, 2004; Davey et al., 2006; Dickman, 1996a; Glen and Dickman,

2005; McKenzie et al., 2007; West, 2008). Two animals which are thought to pose a significant threat to native wildlife are the red fox (Vulpes vulpes) and the feral domestic cat (Felis catus) (Hobbs,

2001; McKenzie et al., 2007; Saunders et al., 1995; Short and Smith, 1994). These carnivores have been blamed for hastening the demise of several species and for threatening the re-establishment of viable native fauna populations (Banks et al., 2000; Burbidge and McKenzie, 1989; Christensen and

Burrows, 1994; Dickman, 1996a; Kinnear et al., 2002; Kirkwood et al., 2005; Lapidge and Henshall,

2002; McKenzie et al., 2007). Recognition of the threat these animals pose to native wildlife has lead to active lethal control of red foxes and feral cats in most Australian habitats (Saunders et al., 1995;

Saunders and McLeod, 2007).

Red foxes and feral cats can have detrimental impacts at many different levels. At the individual level, increased mortality rates directly affect the abundance of prey individuals (Davey et al., 2006;

Reaveley et al., 2009; Smith and Quin, 1996). At the population level, altered population dynamics and community composition (e.g. species diversity) can have flow-on effects for ecosystem processes (Davey et al., 2006; Prober and Patrick Smith, 2009; Reaveley et al., 2009; Ruscoe et al.,

2006; Zavaleta et al., 2001).When novel predators are first introduced to an ecosystem there are often high, unsustainable levels of predation on fauna (Ruscoe et al., 2006), which can lead to ecosystem instability and potential collapse (Short et al., 2002a). This is because predator-prey systems co-evolve over time and remain well matched and persistent, so that native predators can

3 regulate prey abundance and vice versa (Glen et al., 2006b). But Australia’s prey species have

evolved in an environment poor in mammalian predators and have had relatively little time to adapt

to the presence of introduced predators (Salo et al., 2007), making them more vulnerable to

predation and consequently, extinction (Purvis et al., 2000). Russell et al., (2009) proposes that

coexistence between predators and prey is possible if suitable anti-predator behavioural responses

are invoked. Several studies have shown Australian native mammals display anti-predator defence

behaviour against threats from snake, lizard and avian predators (Banks, 1998; Jones et al., 2004;

Jose et al., 2002; McLean et al., 1996; Russell and Banks, 2007), but that their defence behaviour is

inappropriate against novel fox and cat predators, which use different hunting methods and can

infiltrate all types of habitat (Banks, 1998; Blumstein and Daniel, 2002; Jose et al., 2002; May and

Norton, 1996; Short et al., 2002a). Slow life histories (i.e. low fecundity, late sexual maturation,

longer gestation), small populations or geographically restricted species at risk of inbreeding, may be

unable to compensate for increased mortality from invasive predators (Braysher, 1993; Purvis et al.,

2000). These factors combine to make many of Australia’s native mammals highly susceptible to predation by the red fox and feral cat (Banks, 1999; McKenzie et al., 2007; Short and Smith, 1994;

Wallach et al., 2009).

According to Browning (1977), for invasive species to become established successfully in a new environment, they must form a propagule (the minimum number of reproducing animals required to establish a population), and be able to make use of a resource not already being fully exploited; or, the species must exploit a resource more efficiently than a species that is already present. These propagules are most easily formed if the introduced species has a biology that favours rapid establishment, e.g. adaptations suitable for a variety of habitats, a generalist diet, high rates of reproduction and the ability to persist under persecution (Ehrlich, 1989; Lloyd, 1980). The red fox and feral cat possess all of these features which have enabled these predators to rapidly spread across the continent (Figures 2.1 and 2.2) and maintain robust populations.

Figure 2.1 Map of Australia depicting the distribution of red foxes.

Figure 2.2 Map of Australia depicting the distribution of feral domestic cats. Foxes are absent from the north of Australia and some have presumed this to be the result of the presence of large dingo packs which exclude foxes from resources (Johnson and VanDerWal, 2009). Cats do not appear to be limited in their distribution and occur in over 99% of Australia, though population sizes vary according to habitat productivity.

Images from West (2008), (http://feral.org.au/content/PestMaps/NationalMaps.cfm Accessed on 5 04/04/2010)

The Red Fox The red fox is the largest member of the Vulpes genus (Sillero-Zubiri et al., 2004). The red fox is also the most successful and widely distributed of all 11 true fox species (Alderton, 1998). Originating in

the northern hemisphere, the red fox now has a vast distribution, occurring on every continent

except South America and Antarctica (Alderton, 1998; Long, 2003; Saunders et al., 1995). The more

recent increase in distribution is believed to be because: 1) introductions, 2) foxes are opportunistic

generalists with no specific habitat or dietary requirements (Lloyd, 1980; Long, 2003; Saunders et al.,

1995), and 3) a global decrease in the occurrence of large carnivores following persecution and

landscape modification by humans, has lead to increased red fox populations which are good at

exploiting modified environments (Alderton, 1998; May and Norton, 1996; Prugh et al., 2009).

Most of the knowledge about the red fox’s biology is based on research conducted in the northern hemisphere. Whether these demographics apply to foxes in Australia remains largely unknown, but from previous research it is known that male and female foxes exhibit slight dimorphism, with males being slightly larger in order to defend territories (Alderton, 1998; Read and Bowen, 2001). Adults generally have a combined head, body and tail length of up to 1.2 metres, and weigh between 4 and

8kg (Alderton, 1998; Sillero-Zubiri et al., 2004). Mating behaviour involves vocalisations and fighting between males for access to vixens (Alderton, 1998). Mating season in Australia is between June and

August, and during this period the fox dog and vixen are monogamous (Cowan and Tyndale-Biscoe,

1997). Vixens are monoestrous and litter sizes range from 2 to 10 cubs, with an average of 4-6 cubs depending on food availability (Alderton, 1998; Cowan and Tyndale-Biscoe, 1997; Saunders et al.,

1995). Cubs are born in dens (often abandoned rabbit (Oryctolagus cuniculus) warrens) from August to September, and are suckled until four weeks of age (Alderton, 1998; Moehlman, 1989; Saunders et al., 1995). Juveniles are independent by six months of age (Soulsbury et al., 2008), fully grown at

10 months and are sexually active after 12 months (Alderton, 1998; Harris, 1978; Saunders et al.,

1995).

6 Selection of habitat depends on food availability and the dynamics of any pre-existing population of

red foxes (Cavallini and Lovari, 1991; 1994; Lloyd, 1980; Lucherini et al., 1995). Red foxes are

territorial and search for defendable territories after they are weaned (Saunders et al., 1995; von

Schantz, 1981). For example, in Australia, Coman et al. (1991) found that juveniles dispersed up to

30km from their natal territories. Establishment of defendable territories by adult males influences

the distribution of red foxes, especially juveniles moving into an area in search of food and/or a

territory. Red fox territories vary in size from 0.1km2 to more than 20km2 depending on the availability of food resources (Ables, 1969; Cavallini and Lovari, 1994; Coman et al., 1991; White et al., 2006; Zimen, 1984). Resources have also been found to influence the population density of foxes in Australia, which varies from 0.46–3.9 foxes per km2 with higher densities in urban areas (Coman et al., 1991; Marlow et al., 2000; Sillero-Zubiri et al., 2004; von Schantz, 1981). In order to find resources foxes possess extremely sensitive hearing (65, 000 Hertz) and rely heavily on their sense of smell for hunting prey (Alderton, 1998). Foxes are mainly crepuscular and nocturnal, but daytime activity has also been recorded (Alderton, 1998; Cavallini and Lovari, 1994; Meek and Saunders,

2000; Saunders et al., 1995). Strong senses and nocturnal hunting activity allows foxes to predate on a variety of animal taxa, from earthworms and centipedes, to fish, mammals and birds (Ferrari,

1995; Macdonald, 1977; Mukherjee et al., 2009). Red foxes are also capable of infiltrating human habitats and scavenging anthropogenic foods (Contesse et al., 2004; Fascione et al., 2004; Harris,

1981).

Introduction of the Red Fox into Australia The first record of an established red fox population in Australia occurred in Geelong, Victoria, in

1871 (Robley et al., 2004; Rolls, 1969), where foxes thrived, sustained by native wildlife and abundant rabbits (the introduction of which preceded that of the red fox by 12 years) (Williams et al., 1995). The increase in numbers of foxes was so great that by 1888, red foxes had spread into

South Australia (Saunders et al., 1995). Because of their reputation as predators of livestock (Arthur et al., 2010; Lugton, 1993; Rowley, 1970; Sillero-Zubiri et al., 2004), red foxes have been persecuted

7 in Australia for as long as they have been present. The New South Wales districts of Albury and

Corowa first introduced bounties for red fox scalps in 1894 with the hope of reducing fox numbers

(Jarman and Johnson, 1977). Bounties were quickly adopted by districts throughout New South

Wales in an effort to halt the pests’ spread, but these often ended when district boards ran out of

money to keep paying the bounties, and because the red fox population often continued to escalate

regardless of increased hunting (Jarman and Johnson, 1977; Marlow et al., 2000; Saunders et al.,

1995). Foxes appeared in the area around Rawlinna on the Nullabor Plain, Western Australia in 1911,

just 17 years after rabbits had arrived in 1894 (Brooker, 1977). Foxes colonised Western Australia

extremely rapidly and are believed to have become established in the last fox-free forests of the

south west region in the 1930’s (Saunders et al., 1995). It is believed that foxes would never have

spread as far or exploded in numbers if they had not been sustained by rabbits (Saunders et al.,

1995), and if native dingo (Canis lupus dingo) numbers had not been depressed due to heavy persecution by farmers (Corbett, 1995; Johnson and VanDerWal, 2009). Today, foxes are found right across Australia (including their most recent introduction to the island of Tasmania), although their distribution and abundance are reduced in the northern regions of the continent (Figure 2.1). This absence from northern Australia may result from the persistence of large populations of dingoes, which are thought to competitively exclude foxes from food sources (such as carcasses and watering points), around which dingo territories are established (Corbett, 1995; Johnson and VanDerWal,

2009). Where foxes do occur in the north of Australia, population sizes are smaller, presumably as a result of unfavourable tropical temperatures (Saunders et al., 1995; Sillero-Zubiri et al., 2004).

The Feral Cat The domestic cat (Felis catus) is believed to have evolved from the slightly larger African wildcat

(Felis sylvestris), and domesticated approximately 8,000 years ago (Case, 2003a; Dickman, 1996b). A

feral cat is a domestic cat which has no reliance on humans for survival, and lives in self-

8 perpetuating populations (Pearre and Maass, 1998). Possessing excellent hearing and eyesight, and

with a flexible body for speed and climbing, cats are excellent hunters. Male cats are generally larger

than females, and both range in size from 2-8kg (Read and Bowen, 2001). In summer, feral cats are

nocturnal and crepuscular but change to increased diurnal activity in the winter (Jones and Coman,

1982; Meek, 2003).

Cats exhibit habitat selectivity, preferring closed habitats which offer protection from predation and

may offer increased hunting opportunities (Edwards et al., 2002; Meek, 2003). Cat home ranges are influenced by food resources, kinship and distribution of females (Meek, 2003). Burrows et al. (2003)

found that the home ranges of feral cats in the Gibson Desert of WA, ranged from 7 to 12km2.

Similarly, Edwards et al. (2001) tracked male cat movements and recorded an average territory of over 22km2 in arid regions of the Northern Territory. The authors suggest that such large home

ranges may result from nutritional stress in an environment with low prey availability, which is

backed up by evidence for greater overlap between cat territories when food is concentrated in a

few areas (e.g. rubbish tip) (Denny et al., 2002; Kerby and Macdonald, 1988). In productive environments the degree to which male and female cat territories overlap, varies according to personality and resource availability. Occasionally a single male territory may overlap that of several females (Kerby and Macdonald, 1988), but in general cats are solitary and actively avoid each other,

especially if they are territorial males, and not reproductively active (Jones and Coman, 1982; Kerby

and Macdonald, 1988). Jones and Coman (1982) noted that the density of cats fluctuated over time,

peaking during the breeding season (ranging from 0.34 cats per km2 in the winter, to 3.5 cats per

km2 in the summer). Female cats are polyoestrus and usually become reproductively receptive

during the months of spring and summer (Case, 2003b). They can bear up to three litters per

breeding season of 1-10 kittens (average is 4-5 kittens) (Case, 2003b). However, in Australia, feral

kitten survivorship is believed to be low (Brothers et al., 1985).

9 Introduction of the Feral Cat into Australia The date when domestic cats were introduced into Australia remains controversial (Abbott, 2002;

Abbott, 2008; Dickman, 1996b). Some authors believe that cats may have arrived before European

settlers, possibly by surviving ship wrecks off the coast (Burbidge and McKenzie, 1989). However,

following European settlement of Australia, domestic cats spread as rapidly across the continent as

the colonists they accompanied. The invasion of the mainland and several islands (including

Tasmania) was aided by the deliberate release of cats as a form of biocontrol for other introduced

pests (e.g. rabbits, house mice (Mus musculus) and rats (Rattus rattus and Rattus norvegicus)

(Abbott, 2008; Brooker, 1977; Robley et al., 2004). The spread of cats was further aided by a cat’s tendency to wander in search of prey and mating opportunities (Coman and Brunner, 1972). It has been suggested that despite the earlier settlement of the eastern states of Australia, domestic cats may have established feral populations more rapidly in Western Australia (Abbott, 2008). Feral cats were first reported in the south west region of Western Australia during the 1860’s (Abbott, 2008).

By the 1890s, the majority of the Australian continent supported feral cat populations (Abbott,

2002), and today only a number of offshore islands remain free of feral cats (Burbidge and Manly,

2002; Nogales et al., 2004) (Figure 2.2).

Diet of the Red Fox and Feral Cat in Australia Numerous studies have examined the diet of red foxes in Australia, as a means of quantifying their

impact upon native animal species. Despite a long history of association with the human population,

knowledge of the feral cat’s impact on Australian wildlife remains debatable (Bamford, 1995;

Barratt, 1998; Coman and Brunner, 1972; Dickman, 1996b; Fitzgerald, 1988; Tidemann, 1994). A

literature search was therefore conducted in order to determine the extent to which diets have been

investigated within Australia, and to determine any trends or preferences in the diet of foxes and

feral cats.

10 Thirty-six published studies were located which investigate the diet of foxes (35 mainland, 1 island)

(Table 2.1), and 21 studies were found for feral cats in Australia (20 mainland, 1 island) (Table 2.2).

The majority of research into both fox and cat diets has been conducted in the eastern states of

Australia, with New South Wales and Victorian studies dominating the literature (43% of cat papers

and 75% of fox papers) (Figures 2.3 and 2.2). The current study may therefore contribute to

knowledge of red fox and feral cat diets in Western Australia.

Red Fox Stomach contents were used to determine the diet of foxes in 15 out of 36 published studies, 19

analysed scats and two studies used both stomachs and scats (Table 2.1). Fox diet research has been

carried out in ecosystems ranging from mountainous eucalyptus forests, alluvial sand plains, flood

plains and coastal scrub; to grazing land, logged forests and areas of urban development (Brown and

Triggs, 1990; Coman, 1973; Croft and Hone, 1978; Lunney et al., 2002; Martensz, 1971; White et al.,

2006). The proportions that each species or food category comprises of the overall diet vary in

accordance with habitat. For instance, in mountainous regions foxes appear to favour rabbit, bush

rat (Rattus fuscipes) and possum species (brushtail possums, Trichosurus vulpecular, and ringtail

possums, Pseudocheirus peregrinus) (Brown and Triggs, 1990). Whereas, foxes in grazing land

consume mostly rabbit, invertebrates and eastern grey kangaroo carrion (Macropus giganteus)

(Catling, 1988). Although not all papers provided details about every food item or category, it was

obvious that across all seasons, foxes consume mostly introduced mammals and invertebrate

species.

The three studies which report the diet of red foxes in Western Australia, reveal that in coastal conservation and grazing land in the Gascoyne region of the State, diet is dominated by invertebrates, rabbit and sheep (Ovis aries) carrion (Risbey et al., 1999). Red foxes from the grasslands of the Nullabor Plain, prey on numerous reptile species and invertebrates (Brooker,

11 1977); and foxes in central Western Australia eat native rodents and reptiles (Burrows et al., 2003).

No descriptive studies of the diet of foxes in the WA’s south west region were found, although comments on specific prey of foxes appear in papers discussing aspects of the animal’s ecology in the region (Christensen, 1980; Wayne et al., 2006).

Figure 2.3 Map of Australia showing the number of published dietary studies conducted in each state and territory for red foxes.

Figure 2.4 Map of Australia showing the number of published dietary studies conducted in each state and territory for feral cats.

13 Table 2.1 Thirty-six dietary studies of the red fox across Australia.

Note: Thirty-six dietary studies of the red fox (Vulpes vulpes) were conducted in a variety of ecosystems around Australia. The majority of research comes from the eastern states, in particular, New South Wales and Victoria. The method of diet analysis (1. stomach contents, and 2. scat contents), is shown alongside the sample size (n) analysed.

Occurrence of Dietary Items (+/-)

N (Analysis Top 3 Prey Reference Location Ecosystem Method) Items Bird Plant Other Reptile Mammal Amphibian Invertebrates

Baker & Degabriele, (1987). The diet of the red fox (Vulpes vulpes) in Crown land      the Eldorado Hills of north-east between Ovens & Forested land with 26 (1) & 14 Rabbit, plants & Victoria Pilot ranges, Vic pastoral margins (2) invertebrates Prong-snouted blind snake, Brooker (1977). Some notes on the North-western lined earless    mammalian fauna of the western Nullabor Plain, Myall woodland & dragon & Nullarbor Plain, Western Australia Rawlinna, WA open grasslands 19 (1) invertebrates Brown & Triggs, (1990). Diets of wild canids and foxes in East Montane  Gippsland 1983-1987, using East Gippsland, eucalyptus spp. Rabbit, bush rat predator scat analysis Vic forests 534 (2) & possum spp. Brunner et al., (1976). The use of predator scat analysis in a mammal Montane Rabbit, swamp  survey at Dartmouth in north- eucalyptus spp. Unknown No. wallaby & bush eastern Victoria Dartmouth, Vic forests (2) rat Burrows et al., (2003). Controlling Gibson Desert Desert climate Native introduced predators in the Gibson Nature Reserve, sand plains and mammals,      Desert of Western Australia WA dunes with spinifex 4 (1) & 18 (2) reptiles & birds

Dandenong Brunner et al., (1991). Comparison Linear reserve Black rat, house Valley of the diets of foxes, dogs and cats surrounded by 217 (2) mouse & dog      Metropolitan in an urban park suburbia, industries (carrion) Park, Vic & paddocks

14 Occurrence of Dietary Items (+/-)

N (Analysis Top 3 Prey Reference Location Ecosystem Method) Items Bird Plant Other Reptile Mammal Amphibian Invertebrates Catling (1988). Similarities and Rabbit, contrasts in the diets of foxes, invertebrates & Vulpes vulpes, and cats, Felis eastern grey       catus, relative to fluctuating prey Yathong Nature Cleared grassland kangaroo populations and drought Reserve, NSW (ex-grazing land) 288 (1) (carrion) Coates & Wright (2003). Predation Rabbit, of southern brown bandicoots common ringtail Isoodon obesulus by the European Royal Botanic possum &     red fox Vulpes vulpes in south-east Gardens Remnant southern brown Victoria Cranbourne, Vic vegetation reserve 72 (2) bandicoot

Alluvial & volcanic plains, mountainous or        coastal regions Rabbit, sheep Coman, (1973). The diet of red Throughout with mixed (carrion) & foxes, Vulpes vulpes L., in Victoria Victoria vegetations 1299 (1) house mouse Flood plains & marshes, central Croft & Hone (1978). The stomach plains, slopes, high Sheep (carrion),        contents of foxes, Vulpes vulpes, country & coastal rabbit & house collected in New South Wales Throughout NSW regions 899 (1) mouse Glen et al., (2006). Diets of Red-necked sympatric red foxes Vulpes vulpes pademelon, and wild dogs Canis familiaris in the northern brown     Northern River Region, New South Northern Rivers bandicoot & Wales region, NSW Nature reserves 48 (2) swamp wallaby Green & Osborne, (1981). The diet of foxes, Vulpes vulpes (L.), in relation to abundance of prey above Kosciusko Invertebrates,       the winter snowline in New South National Park, Eucalyptus spp. plants & Wales NSW woodlands 1328 (2) antechinus spp. Kirkwood et al., (2005). A Open grazing Short-tailed comparison of the diets of feral cats grassland, reserve Phillip Island, Vic 147 (1) shearwaters,      Felis catus and red foxes Vulpes & small urban rabbit & plants vulpes on Phillip Island, Victoria development 15 Occurrence of Dietary Items (+/-)

N (Analysis Top 3 Prey Reference Location Ecosystem Method) Items Bird Plant Other Reptile Mammal Amphibian Invertebrates Lapidge & Henshall, (2001). Diet of foxes and cats, with evidence of Macropod spp. Lambert, Acton & Acacia spp. predation on yellow-footed rock- (carrion), feral Caranna tablelands & buffel 38 (1)       wallabies (Petrogale xanthopus pig & Stations, QLD grass plains celeris) by foxes, in southwestern invertebrates Queensland Lugton (1993). Diet of red foxes Belah-rosewood Rabbit, (Vulpes vulpes) in south-west New Wentworth, NSW plant communities 212 (1) invertebrates &       South Wales, with relevance to & grazing land sheep (carrion) lamb predation Lunney et al., (1990). Analysis of scats of dogs Canis familiaris and Swamp Mumbulla State Forested land amid foxes Vulpes vulpes (Canidae: 613 (2) wallaby, rabbit       Forest, NSW dairy farms Carnivora) in coastal forests near & cow (carrion) Bega, New South Wales Lunney et al., (2002). Long-term Bush rat, dusky changes in the mammal fauna of Mumbulla Stat Eucalyptus spp. antechinus & logged, coastal forests near Bega, 444 (2)    Forest, NSW forest, logged area long-nosed New South Wales, detected by potoroo analysis of dog and fox scats Mahon, (1999). Predation by feral Land between cats and red foxes and the Gnallan-a-gea Sand dunes with Invertebrates,      dynamics of small mammal Creek & Mulligan spinifex & cane birds & long- populations in arid Australia River, QLD grass 382 (2) haired rat Low density sheep Tero Creek Martensz, (1971). Observations on stations possessing Invertebrates, Station & Gum the food of the fox, Vulpes vulpes low sand dunes 55 (1) red kangaroo        Poplah Station, (L.), in an arid environment with cane grass (carrion), rabbit NSW and black box Canberra, Colo Vale, Albury, Invertebrates, McIntosh, (1963). Food of the fox in Howlong, Cowra, Not specified 409 (1) sheep (carrion)        the Canberra District Griffith & Mildura, & rabbit ACT

16 Occurrence of Dietary Items (+/-)

N (Analysis Top 3 Prey Reference Location Ecosystem Method) Items Bird Plant Other Reptile Mammal Amphibian Invertebrates Meek & Triggs (1998). The food of Heathland Common Bherwerre & foxes, dogs and cats on two conservation ringtail possum, Beecroft 273 (2)        peninsulas in Jervis Bay, New reserves amid black rat & Peninsulas, NSW South Wales urban development plants Invertebrates, Molsher et al., (2000). Temporal, Lake plants & spatial and individual variation in Lake system & Burrendong, 263 (1) eastern grey       the diet of red foxes (Vulpes vulpes) agricultural land NSW kangaroo in central New South Wales (carrion)

Mitchell grass Sheep (carrion), Palmer, (1995). Diet of the red fox Offham Station, plains, open mulga red kangaroo (Vulpes vulpes) in south-western 74 (1)        QLD woodlands & sand (carrion) & Queensland hills rabbit

Paltridge (2002). The diets of cats, Undeveloped, Invertebrates, foxes and dingoes in relation to Tanami Desert, sparsely populated, 126 (2) reptiles &     prey availability in the Tanami NT spinifex sand plains rodents Desert, Northern Territory Read & Bowen, (2001). Population Invertebrates, Sand dunes with dynamics, diet and aspects of the Roxby Downs, rabbit & broad- sparse woodlands 105 (1)        biology of feral cats and foxes in SA banded sand- of Acacia spp. arid South Australia swimmer Risbey et al., (1999). The impact of cats and foxes on the small Conservation Invertebrates, vertebrate fauna of Heirisson Heirisson Prong, reserve & grazing 47 (1) rabbit & sheep      Prong, Western Australia. I. WA land (carrion) Exploring potential impact using diet analysis Common Roberts et al., (2006). Does Baiting National parklands ringtail possum, influence the relative composition of Jervis Bay, NSW & residential 470 (2) long-nosed      the diet of foxes? township bandicoot & black rat

17 Occurrence of Dietary Items (+/-)

N (Analysis Top 3 Prey Reference Location Ecosystem Method) Items Bird Plant Other Reptile Mammal Amphibian Invertebrates Rose et al., (1994). Predation by Heath, low introduced foxes on native Ku-Ring-gai woodland & Plants, mammals: a study of fox scats from Chase National Eucalypt spp. 133 (2) invertebrates &       Ku-ring-gai Chase National Park, Park, NSW forest bordered by birds Sydney suburbia Ryan & Croft (1974). Observations Kinchega on the food of the fox, Vulpes Ex-grazing land Invertebrates, National Park, 99 (1)        vulpes (L.), in Kinchega National with lakes rabbit & plants NSW Park, Menindee, N.S.W Saunders et al., (2004). The diet of foxes (Vulpes vulpes) in south- Invertebrates, Great Dividing Hilly lowland eastern Australia and the potential 509 (1) sheep (carrion)       Range, NSW agricultural areas effects of rabbit haemorrhagic & rabbit disease

18 Table 2.2 Eighteen dietary studies of the feral cat across Australia.

Note: Eighteen dietary studies of the feral cat (Felis catus) were conducted in a variety of ecosystems around Australia. The majority of research comes from the eastern states, in particular, New South Wales and Victoria. The method of diet analysis (1. stomach contents, and 2. scat contents), is shown alongside the sample size (n) analysed.

Occurrence of Dietary Items (+/-)

Reference Location Ecosystem (Analysis Top 3 Prey Items Method) Bird Plant Other Reptile Mammal Amphibian Invertebrates Bamford (1995). Predation by feral cats upon Banksia spp. low Skink, gecko & Cooljarloo, WA 1 (1)     lizards woodland legless lizard Bayly (1976). Observations on the food of the Purple Downs Sandhill & Invertebrates, skink 14 (1)       feral cat (Felis catus) in an arid environment Station, SA tableland areas & dragon spp. Lined earless Brooker (1977). Some notes on the North-western Myall woodland & dragon, mammalian fauna of the western Nullarbor Nullabor Plain, 9 (1)      open grasslands invertebrates & Plain, Western Australia Rawlinna, WA spotted ctenotus Linear reserve Dandenong Valley Common ringtail Brunner et al., (1991). Comparison of the surrounded by Metropolitan Park, 85 (2) possum, house      diets of foxes, dogs and cats in an urban park suburbia, industries Vic mouse & black rat & paddocks Burrows et al., (2003). Controlling introduced Desert climate Native mammals, Gibson Desert predators in the Gibson Desert of Western sand plains and 19 (1) reptiles &      Nature Reserve, WA Australia dunes with spinifex invertebrates Catling (1988). Similarities and contrasts in Rabbit, the diets of foxes, Vulpes vulpes, and cats, Yathong Nature Cleared grassland 112 (1) invertebrates &     Felis catus, relative to fluctuating prey Reserve, NSW (ex-grazing land) house mouse populations and drought Undeveloped bush Household scraps, Coman & Brunner (1972). Food habits of the Throughout Victoria country & grazing 128 (1) house mouse &        feral house cat in Victoria areas rabbit Eucalyptus spp. Victorian mallee & Jones & Coman, (1981). Ecology of the feral woodlands & eastern highlands, Unknown Invertebrates, rabbit cat, Felis catus (L.), in South-Eastern reserves        Victoria & Kinchega No. (1) & house mouse Australia. I. Diet intersperse National Park, NSW agricultural land

19 Horsup & Evans, (1993). Predation by feral Common ringtail cats, Felis catus, on an endangered Taunton Scientific Mixed Acacia spp. possum, Ctenotus 2 (1)     marsupial, the bridled nailtail wallaby, Reserve, Qld woodlands sp. lizard & Onychogalea Fraenata unknown frog sp. Open grazing Kirkwood et al., (2005). A comparison of the grassland, reserve Plants, rabbit & diets of feral cats Felis catus and red foxes Phillip Island, Vic 277 (1)        & small urban house mouse Vulpes vulpes on Phillip Island, Victoria development Lapidge & Henshall, (2001). Diet of foxes and cats, with evidence of predation on yellow- Lambert, Acton & Acacia spp. Fat-tailed dunnart, footed rock-wallabies (Petrogale xanthopus Caranna Stations, tablelands & buffel 49 (1) invertebrates &       celeris) by foxes, in southwestern QLD grass plains house mouse Queensland Land between Mahon, (1999). Predation by feral cats and Gnallan-a-gea Sand dunes with Invertebrates,      red foxes and the dynamics of small mammal Creek & Mulligan spinifex & cane skinks & populations in arid Australia River, QLD grass 377 (2) Pseudomys spp. Crop & grazing Martin et al., (1996). Comparison of the diet House mouse, Wheatbelt & Pilbara lands & native of feral cats from rural and pastoral Western 93 (1) black rat &       regions, WA vegetation Australia invertebrates reserves Heathland Black rat, common Meek & Triggs (1998). The food of foxes, Bherwerre & conservation ringtail possum & dogs and cats on two peninsulas in Jervis Beecroft 8 (2)     reserves amid white-footed Bay, New South Wales Peninsulas, NSW urban development dunnart Molsher et al., (1999). Feeding ecology and Rabbit, population dynamics of the feral cat (Felis Lake Burrendong, Cleared grazing invertebrates & 600 (2)       catus) in relation to the availability of prey in NSW land eastern grey central-eastern New South Wales kangaroo (carrion) Watarrka National Mammals, Paltridge et al., (1997). Diet of the feral cat Park, Tanami Desert Dune habitat, sand 390 (1) invertebrates &        (Felis catus) in central Australia & Barkly Tableland, plains & clay pans reptiles NT Undeveloped, Paltridge (2002). The diets of cats, foxes and Reptiles, sparsely populated, dingoes in relation to prey availability in the Tanami Desert, NT 142 (2) invertebrates &     spinifex sand Tanami Desert, Northern Territory birds plains Read & Bowen, (2001). Population dynamics, Sand dunes with House mouse, royal diet and aspects of the biology of feral cats Roxby Downs, SA sparse woodlands 516 (1) ctenotus & painted        and foxes in arid South Australia of Acacia spp. dragon Risbey et al., (1999). The impact of cats and Conservation Rabbit, house Heirisson Prong, foxes on the small vertebrate fauna of reserve & grazing 171 (1) mouse & ash-grey      WA Heirisson Prong, Western Australia. I. land mouse

20 Exploring potential impact using diet analysis

Triggs et al., (1984). The food of fox, dog and Brown antechinus, Croajingalong Sclerophyll & cat in Croajingalong National Park, south- 48 (2) bush rat & common       National Park, Vic woodland eastern Victoria ringtail possum Little Desert Woolley et al., (1985). Food of introduced Heathland, shrub Mammals, National Park & mammalian predators in two Victorian land & riparian 16 (2) invertebrates &      Wyperfeld National National Parks woodland plants Park, Vic

21 Feral Cat Fourteen out of the 21 published studies on feral cats have used stomach analysis to assess diet (the

remaining seven studies analysed scats) (Table 2.2). The ecosystems that feral cat research was conducted in ranged from sand dunes and woodlands, to grazing land and urban zones (Martin et al., 1996; Meek and Triggs, 1998; Paltridge et al., 1997; Woolley et al., 1985). Like the diet of foxes,

the composition of cat diets varies according to habitat. Cats that came from agricultural land

consume primarily introduced mammals (e.g. rabbit, house mice and black rats); but also

invertebrates and occasionally plants (Catling, 1988; Molsher et al., 1999a). Cats from desert areas consume various reptile species, birds and wallabies (Bayly, 1976; Paltridge et al., 1997), and cats in

conservation parks take ringtail possums and dasyurids (Meek and Triggs, 1998; Triggs et al., 1984).

Of the five studies carried out in Western Australia, a total of 293 cat stomachs have been analysed

(one study reported the contents of only one roadkill cat). These studies revealed that feral cats on

Heirisson Prong in the semi-arid Gascoyne region of the state, rely on rabbits, house mice (Mus musculus) and ash-grey mice (Pseudomys albocinereus), while cats in the more arid habitats consume introduced and native mammals plus reptiles and invertebrates (Bamford, 1995; Brooker,

1977; Burrows et al., 2003; Martin et al., 1996). No research into the diet of south west cats was found, although there are references to putative predation by feral cats in the literature (e.g.

(Wayne et al., 2006).

Foxes and Cats Only 13 Australian studies compared the diet of red foxes and feral cats simultaneously. From this published research it is evident that both predators consume a wide variety of prey, plant matter and sometimes inanimate matter. Mammals and birds are the most consistently eaten prey for both predators in all published studies. Mammals include introduced species (e.g. rabbit, black rat etc), and native species such as ringtail possums and several dasyurid species, plus kangaroo carrion. 22

Reptiles were eaten by both predators (ten studies), or by only one of the predator species (two studies). Amphibians were reported as fox dietary items in four papers, and reported as cat dietary items in only three papers, indicating that amphibians may not be preferred prey (Jones and Coman,

1981). A wide variety of invertebrates were also eaten by both predators, with foxes eating the greatest proportions. Foxes consumed plant matter more frequently than cats, although plants were not always included in analyses or separated into deliberately and accidentally ingested categories.

The three studies of the diet of both foxes and cats in Western Australian ecosystems revealed that both species rely on rabbits as their staple food at the localities studied.

The findings from the Australian literature search highlighted the dominance of mammals in both red fox and feral cat diets. However, both predators eat a broad range of prey items, with the dominant prey species reflecting the most accessible or abundant prey type within the researched habitats.

Chapter 3 General Methods Techniques for Quantifying Diets Research into red fox and feral cat diets in Australia has favoured analysis of scats (Tables 2.1 and

2.2). Scats are easy to collect, unobtrusive and non-invasive to the animal subject, but the

fundamental flaw with scat analysis is that it only surveys food items that survive digestion (Cavallini and Volpi, 1995; Hyslop, 1980). Soft prey (e.g. earthworms); or prey with soft body parts (e.g. amphibians), are rarely observed in scats (Brunner and Wallis, 1986). In contrast, stomach analysis requires access to dead animals and this may explain why stomach analysis is used in fewer studies.

Analysis of red fox and feral cat stomach contents has the advantage of making prey classification easier. The fox chews its food minimally, with smaller prey often being swallowed whole (Lockie,

1959; Witt, 1980), which leaves body parts intact for classification. Cats chew more than foxes as

they have a smaller throat, but food is sliced into pieces (with blade-like carnassial teeth) which are

often still large enough to allow identification (Fitzgerald, 1988).

Research into the diets of various animals has resulted in the development of several approaches to quantifying dietary items. Three methods have been used primarily for previous studies of fox and cat diets within Australia:

1. Numerical counts of individual prey items from each and every stomach sampled.

2. Calculation of the average percentage volume of a food item or category, using either visual

estimates or a physical measurement.

3. Percentage occurrence calculates the percentage of predators within a sample that had fed on a

particular prey type.

All three methods have limitations and particular biases (Cavallini and Volpi, 1995; Hart et al., 2002;

Hyslop, 1980). Counting individual prey items may assign too much importance to prey eaten in

large numbers but which do not comprise much of the total volume of foods eaten (e.g. insects)

(Hart et al., 2002; Hyslop, 1980). Percentage volume is believed to be biased if large prey are

infrequently eaten; or, if food types have differential rates of digestion (e.g. bones vs. liver tissue)

(Hyslop, 1980; Saunders et al., 2004). Percentage occurrence may be sensitive to sampling error, and

it gives little indication of differences in relative amount, or bulk, of different food items (Hart et al.,

2002; Pianka, 1971; Saunders et al., 2004). Saunders et al. (2004) and Hyslop (1980) state that while neither percentage occurrence or percentage volume provide an ideal representation of dietary intake, they remain the easiest and most widely used techniques and can therefore be used for comparative purposes when quantifying diets. These suppositions were reinforced by the Australian diet literature in which percentage area and percentage occurrence were the two most popular food estimates used to quantify fox and cat diets (Tables 3.3 and 3.4). These techniques were therefore to quantify the diet of foxes and cats in the present study. The Index of Relative Importance was used to reduce the error associated with both percentage occurrence and volume estimates.

Study Sites Foxes and cats were collected from 12 sites falling within three IBRA (Interim Biogeographic

Regionalisation for Australia) bioregions of south west Western Australia: the Swan Coastal Plain,

Avon Wheatbelt and the Jarrah Forest (Figure 3.1). These regions have a combined area of approximately 156,500 km2 (Table 3.1), and are threatened by numerous human-mediated processes (Table 3.2). Data on the conservation status of native fauna species found within each bioregion remains unclear (Table 3.3) (ANRM., 2009; Hobbs, 2001).

Figure 3.1 IBRA bioregions of south west Western Australia showing collection sites.

Note: The south west region of Western Australia is one of 25 biodiversity hotspots in the world (Myers et al (2000). IBRA (Interim Biogeographic Regionalisation for Australia) bioregions are shown as different coloured regions. Sample sites where red foxes and feral cats were collected within three bioregions (Swan Coastal Plain, Jarrah Forest and Avon Wheatbelt), are marked with red dots. Moving from the south west coast to north east margin of the region, there is a gradient of decreasing native vegetation in favour of agricultural land (Jarvis, 1979). Map modified from original in National Land and Water Resources Audit, 2001 (DAWA, 2002).

Table 3.1 Land area of three of south west Western Australia's IBRA bioregions.

Note: The total land and remnant vegetation area (in hectares, and as percentage cover) of three bioregions falling within south west Western Australia. The Swan Coastal Plain supports a large human population and has experience related modifications. The Jarrah Forest bioregion has nearly 60% of its native vegetation intact, whilst the once fertile Avon Wheatbelt has only 16% native vegetation remaining having been largely transformed into vast crop and grazing lands since European settlement. Information sourced from Shepherd et al. (2001).

Native Vegetation Area

Bioregion Total Area (ha) ha % Swan Coastal Plain 1,529,235 657,450 43

Jarrah Forest 4,544,335 2,665,480 59

Avon Wheatbelt 9,578,995 1,536,296 16 26

Total Area 15,652,565 4,859,226 39

Table 3.2 Top ten threatening processes to ecosystems south west Western Australia.

Note: These processes are all either directly or indirectly a result of human activity. Importantly, introduced wildlife features on the list and includes the impact of red foxes and feral domestic cats.

Information sourced from Australian National Resources Atlas 2009 (http://www.anra.gov.au/topics/vegetation/assessment/wa/, accessed on 01/08/2010)

Top 10 Threatening Processes to Ecosystems in 3 South West Bioregions vegetation clearing fragmentation grazing pressure feral animals exotic weeds salinity pollution

Table 3.3 Conservation status of organisms in the three sample site bioregions.

Note: SCP – Swan Coastal Plain, JF – Jarrah Forest and AW – Avon Wheatbelt

Information sourced from the Australian National Resources Atlas 2009

(http://wwwanragovau/topics/vegetation/assessment/wa/ibra-avon-wheatbelthtml, accessed 01/08/2010)

Conservation Status Critically Endangered Endangered Vulnerable Bioregion SCP JF AW SCP JF AW SCP JF AW Plant 16 22 38 - 31 37 - 36 34 Mammal - 1 - - 1 1 - 4 2 Bird - - 1 - 3 2 - 5 2 Reptile 1 ------1 Amphibian - 1 - - - - - 2 - Invertebrate 1 - 2 - - 1 - - 1

Total 18 24 41 35 41 47 40

Swan Coastal Plain Bioregion The Swan Coastal Plain is the smallest of the three bioregions from which fox and cat samples were

collected (Table 3.5). The bioregion has a warm, mediterranean climate with an average annual

rainfall of between 600 and 1000mm. Woodlands are comprised mainly of Banksia spp. and tuart

(Eucalyptus gomphocephala), sheoak (Allocasuarina spp.) and paperbark (Melaleuca spp.)

(Herbarium, 1998). Wetlands are important ecosystems in the bioregion and support a great

diversity of fauna and flora (Davis and Froend, 1999). The bioregion has been subjected to a

multitude of environmental disturbances and is threatened primarily by urban and industrial

development and the re-routing of resources to areas associated with the city of Perth. Habitat

fragmentation (more than 60% of the land has been cleared), increasing salinity, eutrophication and

invasive plants and animals are some of the human-mediated stresses threatening the biodiversity

of the bioregion (Table 3.6) (Armstrong and Abbott, 1995; Groom et al., 2000; Mitchell et al., 2003).

Jarrah Forest Bioregion The Jarrah Forest Bioregion is an area of over 4, 500, 000 hectares, and is made up of the Northern

Jarrah Forest and the Southern Jarrah Forest. The Northern Jarrah Forest has an average elevation of

300m with rainfall ranging between 700 mm in the east and north, to 1,100 mm in the west. This

region supports jarrah (Eucalyptus marginata) and marri (Corymbia callophylla) forests, wandoo

(Eucalyptus wandoo), powderbark (Eucalyptus accedens) and Banksia woodlands, with proteaceous heath as common understorey and Agonis spp. shrublands (Herbarium, 1998). The Southern Jarrah

Forest has sandy soils, which results in poor drainage and numerous wetlands (ANRM., 2009).

Rainfall is between 500 mm in the east and 1,200 mm in the south west. Vegetation comprises jarrah and marri forests, and wandoo woodlands with mesic understorey. Wetlands are dominated by paperbarks and swamp yate (Eucalyptus occidentalis) (Herbarium, 1998).

Although the Jarrah Forest Bioregion retains nearly 60% of pre-European vegetation, the biodiversity of forest ecosystems is currently threatened by forestry (including illegal felling) dry land agriculture

28 and grazing (Table 3.7) (Hobbs and Cramer, 2003; Shepherd et al., 2001). Other significant land uses

include: mining, rural urbanisation with its associated roads and power lines, and removal of ground

water for irrigation of crops and horticulture. These processes threaten the perseverance of

numerous plant and animal species by facilitating the invasion of weeds, pathogens (particularly the

plant pathogen Phytophthora cinnamomi), feral herbivores (e.g. rabbits, pigs, and deer) and feral

predators (e.g. foxes and cats) (Williams and Mitchell, 2003).

Avon Wheatbelt Bioregion The Avon Wheatbelt is the largest of the three bioregions where fox and cat carcasses were

collected. Its climate is semi-arid, with annual rainfall increasing from 200mm in the east to 750mm

in the west. Vegetation is dominated by woodlands of mixed eucalypt (Eucalyptus spp.), sheoak, jam

(Acacia acuminata), wandoo and woodlands of Casuarina spp. (Herbarium, 1998). Sand plains

support proteaceous scrub-heaths (Herbarium, 1998), and 60% of plant species throughout the region are endemic (Shedley, 2007).

The Avon Wheatbelt Bioregion has been subject to higher degrees of clearing for agriculture and grazing land than either the Swan Coastal Plain or Jarrah Forests (see maps in Jarvis, (1979). With more than 90% of land cleared for agriculture (Armstrong and Abbott, 1995; Saunders, 1989), there are many threatened ecological communities, all of which are in poor condition, with the trend expected to decline (Beecham, 2003a; 2003b). Less than 16% of native vegetation remains intact within this bioregion (Table 3.1). Fauna species are particularly at risk of extinction because of

geographic isolation caused by habitat fragmentation (Burbidge and McKenzie, 1989; Saunders,

1989). Clearing restricts the distribution of native fauna to small pockets of habitat with fewer

refuges, which facilitates greater invasion by introduced plants and animals such as rabbits, foxes

and cats (May and Norton, 1996; Wardell-Johnson and Horwitz, 2009). Removal of vegetation and

changed fire regimes have altered natural patterns of recovery and succession, which may have

contributed to loss of biodiversity in the Avon Wheatbelt (Beecham, 2003b; Bradstock et al., 2002).

29 Clearing for agriculture, mining and rural development has also impacted waterways by raising the

salt table, causing salination (over 30% of the region is affected), and eutrophication (Halse et al.,

2004; Halse et al., 2003; Hobbs, 1993).

Sample Collection Fox and cat carcasses were collected in association with the Red Card for the Red Fox Programme,

which is co-ordinated by the Western Australian Department of Agriculture and Food. An initiative of two community landcare groups, the Red Card for the Red Fox Programme was started in 2003 with the aim of reducing the numbers of foxes, cats, rabbits, pigs, deer and other pest species, using coordinated culls and 1080 baiting throughout the rural regions of south west Western Australia.

With the help of local hunters a total of 542 foxes and 56 cats from 12 locations were collected and processed in 2010 (Table 3.4). Collection days took place in late summer and the weather on hunting evenings was warm and fine, which is conducive to red fox and feral cat hunting activity (Cavallini and Lovari, 1991; Lucherini et al., 1995).

At each of the 12 study sites, local hunters went shooting for foxes and feral cats between dusk and dawn, 12 - 48 hours before the day of collection. Roadkills were also collected and several carcasses were provided by the Department of Environment and Conservation, and a professional hunter

(Eddie Juras from ‘Feral Invasive Species Eradication Management’). Hunters brought the animal carcasses in to collection points and provided information on the time, date and location of each animal killed (Appendix 1), and a number that corresponded to the appropriate hunter was written in the left ear of each carcass. Foxes and cats were then processed separately in the following manner:

30 Table 3.4 Number of red foxes and feral cats collected from 12 sample sites across three bioregions. No. of Bioregion Sample Sites Foxes No. of Cats Swan Coastal Plain Armadale 4 4 Gingin 33 2 Leschenault 2 2 Jarrah Forest Boyup Brook 63 19 Darkan 172 8 Dwellingup 0 1 Mount Barker 58 8 Williams 10 0 Avon Wheatbelt Corrigin 18 0

Dumbleyung 16 0 Katanning 123 11

Quairading 43 1

TOTAL 542 56

Table 3.5 The total number of fox and cat stomachs collected from four sample sites in south west Western Australia, and the total number of stomachs statistically analysed. Red Fox Feral Cat No. of No. of No. of No. of Stomachs stomachs Stomachs stomachs Sample Site Collected analysed Collected analysed Darkan 172 161 8 6 Katanning 123 113 11 11 Mount Barker 58 54 8 7 Boyup Brook 63 57 19 15

Total 416 385 46 39

31 Each animal was weighed (±0.01kg) and sexed. Animals were identified as adults if nipples protruded in females (indicating previous lactation), and if testes had descended in males. Measurements were taken of the head length (nose to occipital condyles; ±0.25cm), and of the head-body length (nose to base of tail; ±0.5cm) using a dressmaker’s tape. The left hind pes was measured from the top of the hock joint to the end of third tarsal (not including the claw; ±0.25cm) using a 30 centimetre plastic rule. Body condition was rated on a subjective scale of 1 to 3 (1 indicating very poor body condition and 3 indicating very good condition), according to the leanness of the waist, and the amount of body fat covering the ribs and abdominal area (Appendix 2). Coat condition was also rated on a subjective scale of 1 to 3 (1 indicating poor coat condition and 3 indicating very good condition) according to whether there were ectoparasites (e.g. fleas, ticks, mange), and whether the coat was patchy or lacklustre. Animals were then given an external physical examination and any abnormalities or physiological conditions noted (e.g. female appears to be lactating).

Dissections After the measurement data were recorded, foxes and cats were cut open from sternum to groin

(Figure 3.2). The gastrointestinal tract (GIT) was then separated from the mesentery and removed

from the body. As per the requirements of a second concurrent honours project (Dybing et al.,

2010), pieces of string were tied in four places along the GIT: at 1) the oesophageal sphincter, 2) the

pyloric sphincter, 3) the junction between the small intestine and the colon (caecum), and 4) just

before the anus. Any fat along its length was removed before the GIT was placed in a plastic bag

containing a metal tag. Both tag and bag were labelled with a unique identifying number. Bags were

rolled to remove air and sealed. Bags were then frozen in a transportable freezer set at -20⁰ Celsius.

Carcasses were disposed of in local tips or buried by participants of the Red Card for the Red Fox

Programme.

Figure 3.2 Photograph of red fox dissection showing first stages.

Note: fox was cut open from anus to sternum. Liver was inspected for signs of ill health. Stomach and intestines were separated into four sections with knots of string. Stomach and intestines were then removed and placed in a numbered bag. Animal was disposed of. (Photograph taken by Bill Bateman).

Figure 3.3 Photograph of red fox dissection showing second stages (sample stomach).

Note: In the laboratory, stomachs were separated from the intestines and oesophagus by cutting near the gastric sphincters where string was tied. The stomach was then cut open along the lesser curvature (Curvature ventriculi minor). (Photograph taken by William Crawford)

Figure 3.4 Photograph of a red fox’s stomach contents.

Note: Fox was cut open from anus to sternum. Liver was inspected for signs of ill health. Stomach and intestines were separated into four sections with knots of string. Stomach and intestines were then removed and placed in a numbered bag. Animal was disposed of. (Photograph taken by Bill Bateman)

Figure 3.5 Graphic of processing foods on sieve.

Note: Stomach contents were spread across a 20cm diameter 2mm sieve, as represented in Figure 3.6, and the proportions of each food category were estimated as a percentage. The sieve was then placed on top of another 20cm diameter (1mm) sieve, and rinsed gently with water (water pressure was 1L-2L/min). (Diagram34 by Brian Crawford)

The GITs were transported back to the university laboratory and stored in freezers at -20⁰ Celsius,

until they were required for analysis.

Stomach Processing Each gastrointestinal tract was thawed 12-24 hours prior to being removed from its plastic bag and

spread on a tray (Figure 3.3). The metal tag with corresponding animal number was also removed

from the bag, rinsed under warm water and placed to one side. Using the string ties as markers, the

stomach was separated from the intestine by cutting one inch above and below each gastric

sphincter. The intestines and oesophagus were then placed in a new bag marked with correlating

animal number and refrozen for later analysis of intestinal parasites (as part of a second honours

project (Dybing et al., 2010).

The volume of each stomach was calculated by filling a 2 litre graduated flask with 1,500ml of water.

Stomachs were lowered into the flask water and the displacement was recorded (in millilitres) as

‘total stomach volume’. Each stomach was then placed in a 1 litre crystallising dish and cut open

with scissors along the curvature ventriculi minor (lesser curvature) (Figure 3.3). Stomachs were then

inverted and the contents scraped into the dish (Figure 3.4). Stomachs were rinsed in running water

over two 20cm diameter graduated sieves (2mm and 1mm), with the 2mm sieve placed on top of

the 1mm sieve. Once empty, each stomach was submerged once again in the 2L graduated flask, and the displacement measured and recorded, after which the stomach was discarded.

Using a metal scoop and tweezers, the stomach contents were gently separated. Any food item that was delicate was removed and placed in a second crystallising dish for separate washing. It was noted whether each stomach contained maggots or gastrointestinal worms, and a rough estimate of the amount of stomach mucous in the contents was made before washing commenced. The contents were then rinsed out of the dish and into the top sieve with a soft water hose and an average water pressure of 2L/minute. The contents were rinsed until food items were distinguishable, and were then separated. Delicate items were rinsed slowly and with a low water

35 pressure of 1L/minute, to prevent dislodgment of any feature (e.g. snake scales). Next, stomach

contents were grouped and spread across the sieve according to category (e.g. insects, fur, bone,

reptile etc) (Figure 3.4), to estimate the percentage that each category contributed to the overall

surface area of the sieve.

Samples of animals and items found within stomachs were kept as reference specimens and for

future taxonomic classification. The size of any samples kept was determined by their physical

nature. If, for example, a stomach contained a frog then the entire frog was kept in order to enable

classification from numerous body parts. If a stomach contained 100% sheep wool then it was not

necessary to keep it all. A few centimetres of each colour and wool type (e.g. face vs. belly wool) was adequate. Likewise, if there were many invertebrates then several samples of each type were kept.

For example, stomach 367 contained centipedes, moths, beetles and crickets. Several examples of

each species were taken, especially if there were differences in the size or colour of individuals.

Because invertebrates tended to be delicate and broke easily, a variety of body parts were included

if whole samples were absent. These included front and back legs, wings, carapaces and mouth

parts. No attempt was made to classify invertebrates beyond the ‘Order’ phylum.

Hard contents suitable for desiccation were wrapped in paper towels along with the metal tag with corresponding animal number. The contents were placed in a ventilated oven, set at 40⁰Celsius, and dried for 2-4 days depending on the density of items being dried. Once dry, food items were removed from the papers towels and placed in labelled plastic bags and stored according to species and location. Objects that could not be dried in an oven were stored in labelled, 50ml sample pots, filled with 70% ethanol.

Identification of Stomach Contents Mammal remains were classified from whole specimens using numerous Australian field guides and

reference books (Breed and Ford, 2007; Menkhorst, 2001; Strahan, 1999; Triggs, 2003). When the

entire body of an animal was not present, hair was sampled and identified using whole-mount

36 techniques outlined in the mammalian hair identification book by Brunner and Coman (1974), and the CD-ROM by Brunner and Triggs (2002). Guard hairs were placed on glass slides, covered in glycerol and a slide cover placed on top. Slides were then viewed under a compound microscope using 40x-200x magnifications. The medulla of the widest region of the guard hair, termed the shield region, was then compared to photographs of hair mounts from mammalian species found in the south west bioregions of Western Australia.

Meat was classified as either fresh or as carrion, and to species level where possible. Moberly (2003) claims that one of the limitations of stomach analysis is that fresh sheep cannot be differentiated from carrion. Several papers used the presence of maggots as being indicative of carrion; however carrion can reach a stage of decay where flies no longer lay eggs on carcasses and so any scavenged remains may not contain maggots (Gullen and Cranston, 2010). Live sheep also become ‘fly blown’ which may explain the presence of maggots on freshly killed animals. Whilst it may be impossible to know with certainty whether sheep were alive or dead when eaten, it was possible to tentatively classify meat by using odour and texture as the primary techniques to differentiate between states of flesh decomposition. The smell of fresh sheep was dominated by blood and fat, and was pink, soft. Carrion smelt putrid, resembling the smell of diseased flesh, and it was drier and more fragile than fresh meat. Some carrion was so old that it retained little odour and resembled dried meat jerky in texture. The colour of the meat was also indicative of freshness. Fresh meat was pink, whilst ageing meat was off-white to greenish brown in colour. It was also possible to tell the difference between adult sheep and lamb meat if wool and placenta were present. Lamb wool was short, very curled and very white, whereas adult sheep wool was thicker and normally darker (presumably from dirt). The amniotic sac of newborn lambs was distinguishable from other membranes (e.g. intestine) due to its saclike shape, lack of colour and its occurrence without any accompanying body parts or herbage. Where possible, any carrion that did not have the characteristic smell of sheep had hair samples retained for further classification. Mammal remains were also classified as carrion if hair

37 analysis revealed that the prey was a species which grew substantially bigger than the largest fox

(e.g. western grey kangaroo (Macropus fuliginosus) (Witt, 1980).

Bird remains were classified where possible, to species level, with the assistance of Claire Stevenson

(Western Australian Museum), and using a field guide to Western Australian birds (Storr and

Johnstone, 1979). Reptiles and amphibian remains were classified to order and species level where possible, with the assistance of Brad Maryan (Western Australian Museum), and using the field guides by Storr et al. (1999; 2002), Bush et al. (2002) and Tyler et al. (2000). The numerous samples of invertebrates collected from each site were identified with the help of Brian Hanich (Technical

Officer at the Western Australian Museum).

Food Categories In total there were 15 food categories assigned to stomach contents. The fauna ingested included 6

native animal categories and five introduced mammal categories. There was also a single category

for unknown mammal remains.

Ingested plant matter was separated into two categories: deliberate and incidentally ingested plants.

This was based on the type of plant matter consumed. For example: mulberries, figs, grapes, green

grass and seeds were all classified as deliberately ingested food. There was a clear difference

between the grass classified as deliberately eaten, compared to that which was classified as

incidentally consumed. Incidentally consumed grass was dry and straw like, and probably ingested as a result of eating food off of the ground. In comparison, the grass classified as deliberately ingested was green and obviously chewed. Importantly, the deliberately consumed grass did not resemble the grass found in sheep intestines that were eaten (which smelt like ruminant cud), the green grass deliberately eaten by foxes and cats was not pulverised and darkened by rumination. Sometimes a single grass blade was present, and at other times grass accounted for more than 50ml of stomach contents. Twigs, bark, dead grass and weeds were classified as incidentally consumed plant matter as a result of eating food on the ground. The dirt and sand consumed were unable to be quantified.

38 The final food category found in stomachs contained miscellaneous items such as plastic, paper, tin foil and the rings used to dock lamb tails. The worms, maggots and grooming hairs found in fox and cat gastrointestinal tracts, were noted but not included as food categories for statistical analysis.

Stomachs that contained only intestinal worms or those that were empty (including those with less than 2ml of contents) were excluded from data analysis (Table 3.5).

39 Chapter 4 Does Dietary Competition Exist Between Foxes and Cats? Introduction Dietary studies have been used by researchers to establish species’ nutritional intake and any

seasonal variation (Hyslop, 1980). The most obvious information gleaned from diet analysis is

whether a particular prey species is present within a predator’s habitat. The proportions in which

prey are eaten may also tentatively indicate the prevalence of the prey species in a habitat.

Analysis and comparison of the diets of two or more predator species, may also elicit information about the ecology of each predator. For example, the prey species consumed by two predators may reveal preferences that either predator has for a particular prey category, prey age or prey size group. Conversely, the ecology of the prey species may provide information about when two predators are active (e.g. nocturnal prey consumed by a nocturnal predator), and the physical state of consumed foods may reflect the hunting behaviour of the predators (e.g. live prey versus scavenged carrion).

Dietary studies have also been used to draw conclusions about competition between two different species (or sub-groups in a community e.g. gender groups), by comparing dietary intake for similarities and differences. If one prey species is common to two predators, then some competition for that prey may exist (Fedriani et al., 2000) (Figure 4.1). The likelihood of competition existing between two predators is believed to increase with the number of prey species common to both predators (i.e. dietary overlap) (Jones and Barmuta, 1998; Pacala and Roughgarden, 1982) (Figure

4.2).

Figure 4.1 Venn diagram indicating a small overlap in the dietary items consumed by the red fox and feral cat.

Figure 4.2 Venn diagram indicating a large overlap in the7dietary items consumed by the red fox and

Note: These Venn diagrams each show a possible outcome of predator diet analyses. The degree to

which there is overlap in food items potentially reflects the likelihood of competition between the predator species. The blue area in Figure 4.3 indicates a small overlap in the dietary items consumed by the red fox and feral cat. The orange area in Figure 4.4 indicates a large proportion of food items are shared by the red fox and feral cat. (Diagrams by Brian Crawford)

41 Donadio & Buskirk (2006) propose that dietary overlap influences the type and strength of spatial

and temporal interactions between predators. When there is some dietary overlap between

predators, the mechanism for predator interaction is often some form of interspecific competition.

Interspecific competition is defined as interactions between individuals of two species, which

adversely affects one or both of the species (Allaby, 2003; Ritchie and Johnson, 2009). There are two main types of interspecific competition: Exploitation Competition is when one predator species uses resources that deprive another species of that resource (Polis, 1988). Interference Competition is when antagonistic interactions between two predator species result in the physical exclusion of one species from a resource (Glen and Dickman, 2005). Both exploitative and interference competition can occur as a result of competition for carcasses or access to prime habitat. For example: African wild dogs are regularly excluded from carcasses by spotted hyaenas (Creel and Creel, 1996); and red foxes forage for shorter periods of time in resource patches frequented by hyenas (Mukherjee et al.,

2009).

The most extreme form of interspecific competition is intraguild predation, which involves the deliberate killing and eating of one predator species by another (Donadio and Buskirk, 2006; Müller and Brodeur, 2002; Polis et al., 1989). For example, in addition to being excluded from resources by hyaenas, African wild dogs are often preyed upon by lions to reduce competition for food (Creel and

Creel, 1996). Fear can be an outcome of aggression between predator species, and may be strong enough to induce changes in habitat use or activity patterns so that areas defended by a dominant species are avoided and physical conflict is minimised (Mukherjee et al., 2009; Palomares and Caro,

1999; Ritchie and Johnson, 2009; Sergio and Hiraldo, 2008).

The Mesopredator Release Hypothesis (MRH) is a theory based on interactions between two competing species of predator. The MRH proposes that removal of an ecosystem’s top or apex predator will release subordinate mesopredator species from competition and/or predation, leading to an increase in population size of the mesopredator species (Prugh et al., 2009; Ritchie and

42 Johnson, 2009; Soulé et al., 1988). For example, in North America the coyote has been released from competition with grey wolves for access to hunting territories (Berger and Conner, 2008; Switalski,

2003). Persecution of the wolf by humans, has led to increased coyote populations and a dramatic extension of its distribution (Berger and Gese, 2007; Golightly Jr, 1997).

An increased mesopredator population represents a shift in trophic dynamics that can affect species several trophic levels above and below the mesopredator in a food web (Prugh et al., 2009). Where carnivorous mesopredators are released from suppression, they are capable of having a negative impact on prey species, even compromising the perseverance of some species (Choquenot and

Parkes, 2001; Crooks and Soulé, 1999; Terborgh et al., 2001; Wallach et al., 2009; Zavaleta et al.,

2001). Rayner et al (2007) demonstrated that eradication of feral cats from Little Barrier Island in

New Zealand, led to a substantial decrease in the breeding success of Cook’s petrel (Pterodroma cookii) as a result of predation by Pacific rats (Rattus exulans).

In Australia, red foxes and feral cats are recognised as carnivores which predate on native fauna, and are consequently credited with the ability to drive species to extinction (Burbidge and Manly, 2002;

Dickman, 1996b; Short and Smith, 1994; Smith and Quin, 1996). Both species are lethally controlled throughout Australia in an effort to reduce their populations and the risk posed to livestock and native fauna (Burrows et al., 2003; Dexter and Murray, 2009; Parkes et al., 2006). However, in comparison to foxes, cats are harder to locate and shoot, trap or poison (Algar et al., 2007; Molsher,

2001; Short et al., 2002b). Because foxes are thought to suppress feral cat numbers through competition for resources (Molsher, 1999b; Risbey et al., 2000), there is concern amongst the conservation community that reduction of local fox populations may lead to mesopredator release of feral cats . For example, Risbey et al (2000) demonstrated that following the removal of red foxes from Heirisson Prong, Western Australia, the resident feral cat population increased three fold and the number of mammals captured declined by 80%.

43 The south west region of Western Australia supports native fauna that are highly endemic and

critically threatened (Australian Government Department of the Environment, 2009; Gibson et al.,

2010; Hobbs and Mooney, 1998). The impact that foxes and cats could have on native fauna

populations may therefore be significant in the south west region. In order to determine the impact

of foxes and cats on native fauna and in order to predict the likelihood of mesopredator release,

knowledge about predator interactions is required (e.g. dietary and/or spatial competition). Whilst

the present study does not measure the spatial or temporal activity of red foxes and feral cats, it

does analyse and compare the dietary intake of both predators simultaneously from several sample

sites in the south west. Dietary analysis of both foxes and cats will indicate what prey they consume,

and may reflect information about the habitat the predators inhabit. By establishing the degree of

overlap in the diet of the red fox and feral cat, dietary analysis is the first crucial step towards

determining the strength of interspecific competition, and may consequently reveal the likelihood of

mesopredator release occurring in some of Western Australia’s threatened habitats.

Thesis Aims The aims of this Honours thesis are to:

1) Describe the diet of foxes and cats at four sample sites across the south west of Western

Australia.

2) Compare the diets of cats and foxes.

3) Interpret the results in terms of hyperpredation theory.

4) Interpret the results in terms of mesopredator release by testing the following predictions:

I. there is an overlap in fox and cat diets; and

II. there is evidence of intraguild predation.

5) Discuss the likely impact on native West Australian fauna.

44 Methods

Representativeness of Samples In order to determine whether sample sizes of red foxes and feral cats were large enough to

represent all possible foods consumed at sample sites, cumulative frequency (CF) graphs were

created for each species at sample sites which had five or more individuals. Using Microsoft Excel

2007 Program, the cumulative number of food categories (y variable) was plotted against each

individual animal (x variable). Data were plotted separately for foxes and cats at each site. To

determine how large the sample sizes needed to be to maximise representation of all possible food

categories, a logarithmic trend line was plotted against the data points and the coefficient of

determination (r2) was calculated. The coefficient of determination must vary from 0 to +1 with

higher values indicating a close fit between the data and logarithmic trendline. A closely fitted trend

line enables one to visualise where the graph levels out and what the optimal sample size of animals

may be needed in order to represent the full range of food categories.

Quantifying Fox and Cat Diets To quantify the stomach contents of foxes and cats, three equations from the Australian dietary

literature were adopted. Data were then represented in pie-charts, bar graphs and Multi-

Dimensional Scaling figures. Finally, three statistical tests were used to compare fox data, cat data

and fox data with cat data. These methods are explained under the following headings:

1) Percentage Area (A)

2) Percentage Occurrence (F)

3) Index of Relative Importance (IRI)

4) Red fox and feral cat body conditions

5) IRI pie-charts of fox and cat diets at each location

6) Spearman’s Rank Correlation Coefficient (SRCC)

7) Dietary Overlap (O)

45 8) Multi-Dimensional Scaling (MDS) figures; and

9) Analysis of Similarity (ANOSIM) figures

1. Percentage Area The average percentage surface area (A), was defined as: the proportion of the total surface area

occupied by dietary item (i) (when stomach contents were spread across the surface of a circular sieve), averaged across all stomachs (Cavallini and Volpi, 1995).

Each dietary item’s average surface area was calculated using the equation:

Percentage Surface Area i = (∑ Percentage areas of stomachs containing food category i) Total number of stomachs

2. Percentage Occurrence Percentage occurrence (F), defined as the proportion of stomachs in a sample that contained a

particular food item (Hyslop, 1980), was calculated by counting the number of stomachs at each site

that contained a particular food category, dividing this by the total number of stomachs and

multiplying the result by 100 to convert it to a percentage value:

Percentage Occurrence i = 100 x ( Number of stomachs containing food category i) Total number of stomachs

3. Index of Relative Importance Piankas (1971) developed the Index of Relative Importance (IRI), as a measure to reduce the biases

associated with calculations of percentage occurrence (F), percentage area (A) and numerical counts

of all food items in a stomach. The IRI was calculated using the following formula:

Index of Relative Importance i = F (N + V)

46 Where F is the frequency of occurrence (%) of food category i, N is the numerical percentage of food

category i and V is the volumetric percentage of food category i (Pianka and Pianka, 1976; Pianka,

1971).

Because the numbers of items (N) in each food category within stomachs were not counted in the present study, Piankas’ IRI could not be used in its original form. A modified version adopted by

Armstrong and Booth (2005) was used, which utilises only two variables; percentage area (A) and percentage occurrence (F).

The IRI values for every food category consumed by foxes and cats at four sample sites were calculated using the following modified equation:

IRI = (/Index of Relative Importance = ( / =1 ( ))

Where F is the percentage occurrence, A is the percentage surface푖 푡area,퐹푖퐴 t푖 is the number of food

categories and i is the specific food category that the IRI is being calculated for. Because the frequency of percentage occurrence can only be calculated for the total species sample at each site, the IRI is calculated from the sum of all data for each species; and from each sample site.

4. Red fox and feral cat body conditions On the day of collection, red foxes and feral cats were given body condition scores on a scale of one to three (depending on the layer of fat that could be felt on the ribs and belly). The body condition scores were subsequently plotted as column graphs for separate species at each of the sample sites.

Chi-square contingency tables were used to test the hypothesis that there was no significant

association between body condition and predator species, and the hypothesis that there was no

association between site and body condition in foxes. Data for foxes and cats were summed across all sites to test the first hypothesis because the numbers of cats at individual sites was too small for a site by site analysis. Similarly, the sample size for cats was too small to allow a valid test of differences in condition between sites.

5. IRI pie-charts of fox and cat diets at each location Using Microsoft Excel 2007 Program, the IRI values for each food category consumed by foxes and cats at each site, were used to create pie-charts. This allows each food category to be represented as a proportion of 100 presenting an overview of diets at each site.

6. Spearman’s Rank Correlation Coefficient Spearman’s Rank Correlation (SRC) testing was carried out to determine whether both predator

species rank each food category in a similar order of importance. The function is suitable for large sample sizes and importantly, does not assume that there is a linear relationship between the food categories. It therefore does not assign a rank based on differences between food categories, but

instead assesses the order in which they descend from most important to least important.

Significant p-values (α<0.05) indicate that each food category is ranked similarly by both predators.

The IRI values for each food category were compared between foxes and cats, and between sites

within species, using the PAST statistical software, version 2.03 (http://folk.uio.no/ohammer/past)

(Hammer et al., 2001).

To increase sensitivity of comparisons, the IRIs for each area and species were tested against the

average percentage areas of each food category. This was done to determine whether percentage

area could be used as the basis for ANOSIM testing. Since the IRI is a composite measure

(aggregating data to produce summary values for each food category; the IRI therefore has no error

term), a consequence of this summation is the loss of statistical power because individual data are

not used. If percentage area is significantly correlated with the IRI, then the percentage area for each individual animal can be used in place of the IRI, for final ANOSIM testing.

7. Dietary Overlap The percentage IRI values were used to calculate the dietary overlap between red foxes and feral

cats at each sample site, using the equation:

Oij = ∑ percentage minimums (of i or j)

Where i is species 1 (red fox) and j is species 2 (feral cat). All 15 categories were then compared and

the smallest value for each category was summed to give an estimate of dietary overlap.

8. Multi-Dimensional Scaling Multi-Dimensional Scaling (MDS) uses a set of multivariate statistical methods to create a spatial

representation of data, based on distances between data points. MDS figures are presented

graphically with a two dimensional solution that best preserves information from the complete data

set. MDS figures were produced by inserting first the IRI, then the percentage area values, of all

individual foxes and cats from sample sites into PAST statistical software, version 2.03

(http://folk.uio.no/ohammer/past) (Hammer et al., 2001). The MDS figures were created using Bray-

Curtis similarities (a dissimilarity measure that has performed consistently well in a variety of tests and simulations on different types of data (Faith et al., 1987). Convex hulls (which are polygons with the smallest number of sides that encompass all data points in a sample), were added to aid graphical interpretation.

9. Analysis of Similarity The Analysis of Similarity (ANOSIM) is an analogue of ANOVA and compares the distances between

data points within two or more groups (such as the diets of predators at different sites), with the

distances between points in different groups to test whether or not the two groups are distinct

49 (Clarke and Warwick, 2001). This is assessed with a statistic known as R, where a large positive R (to a maximum of +1), indicates that animals between sites and between species differ from each other

(α<0.05). One-way ANOSIMs tested for similarity using food category percentage areas of individual animals from both species. ANOSIMs were created using PAST statistical software, version 2.03

(http://folk.uio.no/ohammer/past) (Hammer et al., 2001), and the Bray-Curtis similarity measure.

Results

Representativeness of Samples A total of 542 foxes and 56 feral cats were collected from across south west Western Australia.

Foxes and cats were both shot at 11 out of 12 sites, but only four sites had sample sizes of five or

more individuals for both species (Table 3.4). These four sites were: Darkan (Jarrah Forest),

Katanning (Avon Wheatbelt), Mount Barker (Jarrah Forest) and Boyup Brook (Jarrah Forest). All

subsequent analyses were carried out on these four sample sites only.

The number of stomachs used in statistical analyses was less than the total number collected for

foxes and cats at each sample site, due to elimination of stomachs that were unsuitable (stomachs

that were empty, contained only gastrointestinal worms, or those which contained less than 2ml of

content) (Table 3.5). However, following the removal of several stomachs from analyses, the

cumulative frequency graphs (number o/f animals versus number of food categories), still indicated

that sample sizes of foxes and cats caught at each of the four sites approached sizes adequate for

further statistical analysis (Figures 4.3 to 4.10).

50 Quantifying Predator Diets

Description of Red Fox Diet Spearman’s rank correlation coefficient testing indicated that there was no significant difference

between average percentage surface area and percentage occurrence estimates at any of the four

sample sites (Tables 4.1, 4.2 and 4.3). This allows the percentage area measurements from each

individual fox to be used in place of the composite IRI measures. This substitution increases the

sensitivity of results from further statistical analyses.

Dietary overlap in the range of dietary items consumed by foxes at all sites was an average of 84%

(Table 4.4). This was confirmed by the MDS figure (Figure 4.12) and the ANOSIM testing (ANOSIM

Tables 4.6 and 4.6), which indicated that there was no statistical difference in the diets of foxes from

the four sites (R=0.0107, p=0.2713).

The body condition of red foxes was generally good (Figure 4.11 & Table 4.5). Twenty percent of all

foxes had body condition scores of 1 (very poor condition). Sixty-three percent of foxes had a body

condition score of 2 (good condition), and 17% of foxes had a body condition score of 3 (excellent

condition). Foxes from Mount Barker had the best body conditions and foxes from Darkan had the

worst body conditions. Chi-squared contingency table confirmed that the condition of foxes was

associated significantly with site (X2=9.7, df=2, p=0.008).

Overall, foxes ate food items from 15 food categories. Native animal categories included: 1) the fat- tailed dunnart (Sminthopsis crassicaudata), 2) the brushtail possum (Trichosurus vulpecula), 3)

numerous bird species, 4) several species of reptile, 5) several species of amphibian, and, 6)

numerous invertebrate orders (Appendix 3). The introduced fauna included: 1) sheep (Ovis aries), 2)

cattle (Bos taurus), 3) rabbit (Oryctolagus cuniculus), 4) house mouse (Mus musculus), and, 5) black

rat (Rattus rattus) categories (Appendix 3). There was also an ‘unknown mammal’ food category.

Ingested plant matter was separated into two categories according to whether it was eaten

51 deliberately or incidentally with other food items. A ‘miscellaneous food’ category was also included and contained items like plastic and paper.

Based on the IRI values and across all four sites, the dominant diet item was sheep carrion, which made up 64% of the overall diet (Figures 4.13 to 4.16 and 4.23). Meat and wool were the primary body parts ingested. There were only 13 occurrences of fresh sheep (although only 19 of 385 stomachs analysed had maggots), and six fox stomachs contained the remains of what was judged to be lamb. Sheep was followed in importance by deliberately eaten plants which made up 12% of fox diet with grass, seeds, wheat, millet, corn, and fruit the main plants eaten. Invertebrates made up

9% of all dietary items (orders consumed the most were Orthoptera and Coleoptera). Rabbits, house mice and black rats combined made up 7% of the diet, and native vertebrate animals comprised a total of 6%.

52 16 16

14 14

12 12

10 10

8 8 y = 2.1886ln(x) + 3.6016 y = 1.9321ln(x) + 4.166 R² = 0.8983 R² = 0.838 6 6

No. of Food Categories Eaten Categories Food of No.

No. of Food Categories Eaten Categories Food of No. 4 4

2 2

0 0 0 50 100 150 200 0 50 100 150

No. of Stomachs No. of Stomachs

Figure 4.3 Accumulation curves of dietary categories for red Figure 4.4 Accumulation curves of dietary categories foxes at Darkan (n=161). for red foxes at Katanning (n=113).

12 12

10 10

8 8

6 6

y = 2.0774ln(x) + 1.2604 y = 2.653ln(x) - 0.252 4 R² = 0.9389 4 R² = 0.8552

No. of Food Categories Eaten Categories Food of No. No. of Food Categories Eaten Categories Food of No. 2 2

0 0 0 20 40 60 0 20 40 60 No. of Stomachs No. of Stomachs

Figure 4.5 Accumulation curves of dietary categories for Figure 4.6 Accumulation curves of dietary categories for red foxes at Mount Barker (n=54). red foxes at Boyup Brook (n=57).

Note: Cumulative frequency of food categories consumed by feral cats at four sample sites in the south west region of Western Australia. Logarithmic trend lines (equation shown) were fitted to cumulative frequencies. Graphs created using Microsoft Excel 2007.

53 6 10

9 5

7 4 6

3 5 y = 2.8148ln(x) + 2.3394 y = 2.5481ln(x) + 0.8726 R² = 0.9297 4 R² = 0.9639 2 3 No. of Food Categories Eaten Categories Food of No. No. of Food Categories Eaten Categories Food of No. 2 1 1

0 0 0 2 4 6 8 10 12 0 2 4 6 8 No. of Stomachs No. of Stomachs

Figure 4.7 Accumulation curves of dietary categories Figure 4.8 Accumulation curves of dietary categories for feral cats at Darkan (n=6). for feral cats at Katanning (n=11).

8 8

7 7

6 6

5 5

4 4

3 3 y = 2.5813ln(x) + 0.7323 y = 2.2063ln(x) + 2.1701 R² = 0.924 R² = 0.8126 Eaten Categories Food of No.

No. of Food Categories Eaten Categories Food of No. 2 2

1 1

0 0 0 5 10 15 20 0 2 4 6 8 No. of Stomachs No. of Stomachs

Figure 4.9 Accumulation curves of dietary categories for feral cats at Mount Barker (n=7). Figure 4.10 Accumulation curves of dietary categories for feral cats at Boyup Brook (n=15).

Note: The above figures show cumulative frequency of food categories consumed by feral cats at four

sample sites in the south west region of Western Australia. Logarithmic trend lines (equation shown) were fitted to cumulative frequencies. Graphs created using Microsoft Excel 2007.

54 Table 4.1 Average values of percentage surface area, frequency of occurrence, and Index of Relative Importance, for each dietary category of red foxes and feral cats.

Note: Percentage areas (A),

tailed frequency of occurrence - percentages (F), and Index of Site Species Statistical Method Total Sheep Cattle Rabbit House Mouse Rat Brushtail Possum Fat Dunnart Unknown Mammal Bird Reptile Amphibian Invertebrates Plant Deliberate Matter Incidental Plant Matter Other Relative Importance (IRI) values Darkin Fox Volume (%) 78.41 0.00 81.75 8.67 0.00 1.50 0.00 3.50 25.70 8.78 46.25 23.37 20.35 7.35 1.00 for 15 food categories consumed Frequency of Occurrence (%) 76.97 0.00 7.27 1.82 0.00 1.21 0.00 1.21 13.94 5.45 2.42 49.09 43.64 12.12 1.21 at four locations in the south west IRI 0.64 0.00 0.06 0.01 0.00 0.00 0.00 0.00 0.04 0.01 0.01 0.12 0.09 0.01 0.00 of Western Australia. Cat Volume (%) 22.50 0.00 0.00 0.00 0.00 0.00 0.00 0.00 85.00 0.00 0.00 0.00 61.67 12.50 0.00

Table created using Microsoft Frequency of Occurrence Excel 2007. (%) 25.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 37.50 0.00 0.00 0.00 37.50 25.00 0.00 IRI 0.10 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.57 0.00 0.00 0.00 0.28 0.06 0.00

Darkan Katanning Fox Volume (%) 79.38 10.50 39.00 24.36 0.00 50.00 30.00 0.00 16.21 15.60 10.00 15.75 25.20 14.21 9.57

Kantanning Frequency of Occurrence Mount Barker (%) 85.59 1.69 1.69 11.86 0.00 1.69 0.85 0.00 11.86 4.24 0.85 23.73 45.76 11.86 5.93 IRI 0.71 0.00 0.01 0.06 0.00 0.01 0.00 0.00 0.02 0.01 0.00 0.04 0.12 0.02 0.01 Boyup Brook Cat Volume (%) 20.00 0.00 0.00 0.00 0.00 0.00 30.00 40.00 51.86 35.00 52.50 18.75 20.00 55.00 10.00

Frequency of Occurrence (%) 18.18 0.00 0.00 0.00 0.00 0.00 9.09 9.09 63.64 18.18 0.00 18.18 36.36 9.09 18.18 IRI 0.05 0.00 0.00 0.00 0.00 0.00 0.04 0.05 0.49 0.10 0.00 0.05 0.11 0.07 0.03

Mt Barker Fox Volume (%) 70.52 0.00 0.00 41.70 50.00 0.00 0.00 27.00 34.75 10.00 4.00 21.55 32.54 19.60 0.00 Frequency of Occurrence (%) 73.68 0.00 0.00 17.54 3.51 0.00 0.00 5.26 14.04 3.51 1.75 40.35 47.37 17.54 0.00 IRI 0.55 0.00 0.00 0.08 0.02 0.00 0.00 0.02 0.05 0.00 0.00 0.09 0.16 0.04 0.00 Cat Volume (%) 0.00 0.00 0.00 72.50 92.50 0.00 0.00 0.00 22.00 56.00 0.00 12.00 0.00 3.50 6.00

Frequency of Occurrence (%) 0.00 0.00 0.00 57.14 28.57 0.00 0.00 0.00 42.86 28.57 0.00 14.29 0.00 28.57 14.29 IRI 0.00 0.00 0.00 0.43 0.27 0.00 0.00 0.00 0.10 0.17 0.00 0.02 0.00 0.01 0.01 Boyup Brook Fox Volume (%) 67.20 0.00 56.00 21.25 0.00 15.00 0.00 2.50 35.27 0.00 5.00 16.06 22.76 19.54 10.75

Frequency of Occurrence (%) 93.10 0.00 1.72 13.79 0.00 1.72 0.00 3.45 18.97 0.00 1.72 56.90 43.10 22.41 6.90 IRI 0.64 0.00 0.01 0.03 0.00 0.00 0.00 0.00 0.07 0.00 0.00 0.09 0.10 0.05 0.01 Cat Volume (%) 63.75 0.00 0.00 87.00 0.00 0.00 0.00 92.00 97.50 0.00 0.00 21.67 53.30 45.0055 0.00 Frequency of Occurrence (%) 22.22 0.00 0.00 16.67 0.00 0.00 0.00 5.56 11.11 0.00 0.00 16.67 55.56 16.67 0.00 IRI 0.17 0.00 0.00 0.18 0.00 0.00 0.00 0.06 0.13 0.00 0.00 0.04 0.32 0.09 0.00

Table 4.2 Spearman’s rank correlation coefficient tests percentage surface area against IRI values for foxes and cats. Note: Spearman’s rank correlation coefficient was used to compare the percentage surface area values of individual foxes and cats at each sample site, with the average Index of Relative Importance values, to see whether there was a significant difference between the two dietary measures. Table created using Microsoft Excel 2007 and table values generated by PAST software (Hammer, 2001).

Fox Cat

Spearman's Spearman's Ranked Ranked Correlation p Value Correlation p Value Location Coefficient (<0.05) Coefficient (<0.05) Darkan 0.875 <0.0001 1 <0.0001 Katanning 0.559 0.0303 0.66 0.007 Mt Barker 0.84 <0.0001 0.994 <0.0001 Boyup Brook 0.838 <0.0001 0.908 <0.0001

Table 4.3 Spearman’s rank correlation coefficient tests average IRI values for red foxes against IRI values for feral cats.

Spearman’s rank correlation coefficient was used to compare the fox IRI food category values with the IRI food category values of cats, at each sample site. Table created using Microsoft Excel 2007 and table values generated by PAST software (Hammer, 2001).

Spearman's Ranked p Value Location Correlation Coefficient (<0.05)

Darkan 0.569 0.027

Katanning 0.469 0.078

Mt Barker 0.236 0.396

Boyup Brook 0.783 0.00056

56 Table 4.4 Dietary overlap between red foxes and feral cats at four sample sites.

Note: Dietary overlap (O) between foxes and cats was calculated for the four sample sites across south west Western Australia. The average overlap between foxes and cats from all 4 sites was approximately 26%. Table created using Microsoft Excel 2007.

Darkan Katanning Mount Barker Boyup Brook

Sample Site Darkan Katanning Mt Barker Boyup Brook

Species Fox Cat Fox Cat Fox Cat Fox Cat

Fox 1 24 83 25 79 9 89 36

Darkan Cat 24 1 26 71 35 11 32 57

Fox 83 26 1 16 81 13 87 43

Katanning Cat 25 71 16 1 32 24 33 55

Fox 79 35 81 32 1 18 86 56

Mt Barker Cat 9 11 13 24 18 1 14 31

Fox 89 32 87 33 86 14 1 46

Boyup Brook Cat 36 57 43 55 56 31 46 1

Table 4.5 Body condition scores of red foxes and feral cats at four sample sites.

Body Condition No. of Foxes

Sample Site 1 2 3

Darkan 58 76 27 161

Katanning 9 82 22 113

Mount Barker 2 44 8 54

Boyup Brook 8 40 9 57

No. of Foxes 77 242 66 385

Note: Body condition scores of 385 red foxes from Darkan, Katanning, Mount Barker and Boyup Brook in south west Western Australia. Body Score 1= Very poor condition; Body Score 2= Average condition; and, Body Score 3= Very good condition. Table created using Microsoft Excel 2007.

30 Number of Red Foxes 20

0 Darkan Katanning Mount Barker Boyup Brook

Sample Sites

Figure 4.11 Body condition scores of red foxes from four sample sites.

Note: Body condition scores of 385 red foxes from Darkan, Katanning, Mount Barker and Boyup Brook 58in south west of Western Australia. Body Score 1= Very poor condition; Body Score 2= Average condition; and, Body Score 3= Very good condition. Graph created using Microsoft Excel 2007

0.16

0.12

0.08

a 0.04 d.

c. Coordinate 2

-0.04

b. -0.08

-0.12

-0.16

-0.2 -0.18 -0.15 -0.12 -0.09 -0.06 -0.03 0 0.03 0.06 Coordinate 1

Figure 4.12 Multi-Dimensional Scaling figure showing overlap in the diets of red foxes from four sample sites. a. Darkan b. Kantanning c. Mt. Barker d. Boyup Brook

Note: Multi-Dimensional Scaling (MDS) figure of the percentage surface areas of 15 food categories eaten by red foxes at four sample sites in the south west region of Western Australia. Convex hulls were added around data points to clearly illustrate the overlap between the fox diets at each site. Figure generated with PAST software (Hammer, 2001).

Table 4.6 P-value: Analysis of similarity test results for red foxes at four sample sites.

Sample Site Darkan Katanning Mt Barker Boyup Brook

Darkan 0.8746 0.2108 0.7187

Katanning 0.8746 0.0043 0.0448

Mt Barker 0.2108 0.0043 0.2446

Boyup Brook 0.7187 0.0448 0.2446

Table 4.7 R value: Analysis of similarity test results for red foxes at four sample sites.

Sample Site Darkan Katanning Mt Barker Boyup Brook

Darkan -0.01576 0.03296 -0.0244

Katanning -0.01576 0.1121 0.06158

Mt Barker 0.03296 0.1121 0.003869

Boyup Brook -0.0244 0.06158 0.003869

Note: An analysis of similarity (ANOSIM) statistical test was conducted in order to ascertain whether red foxes from four sample site across the south west region of Western Australia were eating similar diets. An overall R value of 0.0107 and p-value of 0.2713 indicates that diets do not significantly vary with location. Individual comparisons between the four sites produced Table 4.3 (p-value), and Table 4.4 (R value). Tables created using Microsoft Excel 2007 and tables’ values generated by PAST 60 software (Hammer, 2001).

Figure 4.13 Pie chart of IRI values for the 15 food categories eaten by red foxes at Katanning.

Figure 4.14 Pie chart of IRI values for the 15 food categories eaten by red foxes at Darkan.

Note: the 15 food categories listed above apply to both pie charts.

Graphs created using Microsoft Excel 2007.

Figure 4.15 Pie chart of IRI values for the 15 food categories eaten by red foxes at Mount Barker.

Figure 4.16 Pie chart of IRI values for the 15 food categories eaten by red foxes at Boyup Brook.

Note: the 15 food categories listed immediately above apply to both pie charts.

Graphs created using Microsoft Excel 2007.

Description of Feral Cat Diet Spearman’s rank correlation coefficient testing of IRI values versus average percentage area values

produced significant p-values for all four sample sites (Tables 4.1 & 4.2). This indicated that the percentage area estimates for each feral cat could be used in place of IRI values in further statistical analyses, which would increase the sensitivity of results.

Dietary overlap between cats from all sites was estimated to be 41.5% (Table 4.4). MDS figures confirmed that the overlap in the diets of cats from different study sites was not absolute (Figure

4.18). While the ANOSIM results indicated that there was no statistically significant difference in the diets of cats taken from the four study areas (R=0.0758, p=0.064) (ANOSIM Tables 4.9 and 4.10), the p-value approaches significance which suggests there may be some small differences in the diet of cats according to location.

The body condition of feral cats was generally good (Table 4.8 & Figure 4.17). Eight percent of all cats had body condition scores of 1 (very poor condition). Fifty-six percent of cats had a body condition score of 2 (good condition), and 36% of cats had a body condition score of 3 (excellent condition). Feral cats from Boyup Brook had the best body conditions and cats from Darkan had the worst body conditions.

The number of food categories consumed by feral cats ranged from five at Darkan to a maximum of ten categories at Katanning (a total of 11 categories) (Figures 4.19 to 4.22). Native animal categories

included: 1) the fat-tailed dunnart, 2) numerous bird species, 3) several species of reptile, and, 4) numerous invertebrate orders (Appendix 3). The introduced fauna included: 1) sheep, 2) house mouse, and, 3) black rat categories (Appendix 3). There was an additional ‘unknown mammal’ food

category. Cats also ate food stuffs from both plant categories and the ‘miscellaneous food’ category.

Across the four sample sites the IRI values for the various food categories demonstrate that the native birds category was the most important food category overall, making up 32% of the overall

diet (Figure 4.24). Deliberately ingested plants (18%) and house mice (15%) followed birds as

important diet categories. There were however, differences in the primary food source consumed by individuals at different sample sites. For instance, cats from Darkan and Katanning consumed primarily birds (28%), whereas cats from Mount Barker ate mostly house mice (27%); and cats from

Boyup Brook consumed mostly grass (32%).

Comparison of Red Fox and Feral Cat Diets The overlap between foxes and cat diets at each sample site was calculated to be approximately 26%

(Table 4.4). Comparison of the IRI values of feral cats and red foxes indicated that food categories were ranked in the same order of importance by both species at Darkan and Boyup Brook, but in a different order at Katanning and Mount Barker (Tables 4.1 and 4.3).

ANOSIM results also indicate that the diets of foxes and cats are statistically different (R=0.1352, p<0.0001) (Tables 4.9 and 4.10). The R value is modest but highly significant which denotes that overall, foxes and cats in the study period of late summer are consuming different proportions of prey from different prey categories. These differences in dietary proportions are confirmed by analysis of dietary pie-charts (Figures 4.23 and 4.24). Foxes consumed all food categories but cats did not eat any cattle remains, rabbits, possums or amphibians. Cats clearly took more live native prey than foxes, with birds, house mice and black rats the categories consumed most. Foxes consumed sheep carrion, invertebrates and deliberately eaten plants to a much greater extent than cats.

Chi-square contingency testing produced a significant result for an association between condition and predator species, with a higher proportion of cats in the ‘good’ and ‘very good’ body condition categories (X2=49.08, df=6, p<0.0001). Sample sizes for cats were too small to see if a similar

association between fox and cat condition occurred at each individual site.

Table 4.8 Body condition scores of feral cats from four sample sites.

Body Condition Score No. of Cats

Sample Site 1 2 3

Darkan 2 1 3 6

Katanning 0 5 6 11

Mount Barker 0 4 3 7

Boyup Brook 1 12 2 15

No. of Cats 4 22 14 39

Note: Body condition scores of feral cats from Darkan, Katanning, Mount Barker and Boyup Brook in south west Western Australia. Body Score 1 = Very poor condition; Body Score 2 = Average condition; and Body Score 3 = Very good condition. Table created using Microsoft Excel 2007.

14 Feral Cat Body Conditions 12

Number of Feral Cats 0 Darkan Katanning Mount Barker Boyup Brook

Sample Sites

Figure 4.17 Body condition scores of feral cats from four sample sites.

Note: Body condition scores of 39 feral cats from Darkan, Katanning, Mount Barker and Boyup Brook in south west of Western Australia. Body Score 1 = Very poor condition Body Score 2 = Average condition Body Score 3 = Very good condition. Graph created using Microsoft Excel 2007.

65 0.25

0.2

0.15

0.1

0.05 Coordinate 2

-0.05

-0.1

-0.15

-0.2 -0.3 -0.24 -0.18 -0.12 -0.06 0 0.06 0.12 0.18 0.24 Coordinate 1

Figure 4.18 Multi-Dimensional Scaling figure overlap in diets of feral cats from four sample sites.

a. Darkan b. Katanning c. Mt. Barker d. Boyup Brook

Note: Multi-Dimensional Scaling (MDS) figure of the percentage surface area values of 15 food categories eaten by feral cats at four sample sites in the south west region of Western Australia. Convex hulls were added around data points to clearly illustrate the overlap between the cat diets at each site. Figure generated with PAST software (Hammer, 2001).

Table 4.9 P-value: Analysis of similarity test results for feral cats at four sample sites.

Sample Site Darkan Katanning Mt Barker Boyup Brook

Darkan 0.6494 0.2631 0.3373

Katanning 0.6494 0.1353 0.1214 66

Mt Barker 0.2631 0.1353 0.0063

Boyup Brook 0.3373 0.1214 0.0063

Table 4.10 R value: Analysis of similarity test results for feral cats at four sample sites.

Sample Site Darkan Katanning Mt Barker Boyup Brook

Darkan -0.05043 0.05291 0.02306

Katanning -0.05043 0.0974 0.06818

Mt Barker 0.05291 0.0974 0.2324

Boyup Brook 0.02306 0.06818 0.2324

Note: Analysis of similarity (ANOSIM) statistical test was conducted in order to ascertain whether feral cats from four sample sites across the south west region of Western Australia were eating similar diets. An overall R value of 0.0758 and p-value of 0.064 indicates that diets vary in association with location. Individual comparisons between the four sites produced Table 4.5 (p- value), and Table 4.6 (R value). Tables created using Microsoft Excel 2007 and tables’ values generated by PAST software (Hammer, 2001).

Figure 4.19 Pie chart of IRI values for the 15 food categories eaten by feral cats at Darkan.

Figure 4.20 Pie chart of IRI values for the 15 food categories eaten by feral cats at Katanning.

Note: the 15 food categories listed immediately above apply to both pie charts.

Graphs created using Microsoft Excel 2007. 68

Figure 4.21 Pie chart of IRI values for the 15 food categories eaten by feral cats at Mount Barker.

d. Boyup Brook

Figure 4.22 Pie chart of IRI values for the 15 food categories eaten by feral cats at Boyup Brook.

Note: the 15 food categories listed immediately above apply to both pie charts. 69 Graphs created using Microsoft Excel 2007.

Figure 4.23 Pie chart of red fox diet proportions overall, calculated from average IRI values.

Figure 4.24 Pie chart of feral cat diet proportions overall, calculated from average IRI values.

Note: Pie-charts of the IRI values for the 15 food categories eaten overall by red foxes and feral cats at four sample sites: Darkan, Katanning, Mount Barker and Boyup Brook. Graphs created using Microsoft Excel 2007. 70 Table 4.11 P-value: Analysis of similarity test results for red foxes and feral cats at four sample sites.

FOXES CATS

Sample Site Darkan Katanning Mt Barker Boyup Brook Darkan Katanning Mt Barker Boyup Brook

Darkan 0.8776 0.2101 0.7149 0.0002 <0.0001 <0.0001 <0.0001

Katanning 0.8776 0.0059 0.0453 <0.0001 <0.0001 <0.0001 <0.0001

Mt Barker 0.2101 0.0059 0.2419 0.0015 <0.0001 <0.0001 0.0002 FOXES Boyup Brook 0.7149 0.0453 0.2419 <0.0001 <0.0001 <0.0001 <0.0001 Darkan 0.0002 <0.0001 0.0015 <0.0001 0.6507 0.2529 0.3418 Katanning <0.0001 <0.0001 <0.0001 <0.0001 0.6507 0.1321 0.117 Mt Barker <0.0001 <0.0001 <0.0001 <0.0001 0.2529 0.1321 0.0048 CATS Boyup Brook <0.0001 <0.0001 0.0002 <0.0001 0.3418 0.117 0.0048

Table 4.12 R value: Analysis of similarity test results for red foxes and feral cats at four sample sites.

FOXES CATS

Sample Site Darkan Katanning Mt Barker Boyup Brook Darkan Katanning Mt Barker Boyup Brook

Darkan -0.01576 0.03296 -0.0244 0.5217 0.5562 0.6894 0.4163 Katanning -0.01576 0.1121 0.06158 0.7085 0.7416 0.8183 0.5573 Mt Barker 0.03296 0.1121 0.003869 0.468 0.5068 0.6441 0.3297 FOXES Boyup Brook -0.0244 0.06158 0.003869 0.6408 0.6834 0.83 0.4902 Darkan 0.5217 0.7085 0.468 0.6408 -0.05043 0.05291 0.02306 Katanning 0.5562 0.7416 0.5068 0.6834 -0.05043 0.0974 0.06818 Mt Barker 0.6894 0.8183 0.6441 0.83 0.05291 0.0974 0.232471 CATS Boyup Brook 0.4163 0.5573 0.3297 0.4902 0.02306 0.06818 0.2324

Note: An analysis of similarity (ANOSIM) statistical test was conducted in order to ascertain whether feral cats and red foxes from four sample sites across the south west region of Western Australia were eating similar diets. An overall R value of 0.1352 and p-value of <0.0001 indicates that fox and cat diets vary. Individual comparisons between the two species at each of the four sites produced Table 4.7 (p-value), and Table 4.8 (R value). Tables created using Microsoft Excel 2007 and tables’ values generated by PAST software (Hammer, 2001).

Chapter 5 Discussion Overview and Interpretation of Principal Findings This study investigated the diets of red foxes and feral cats in south west Western Australia. The

principal findings of the study are outlined in context of the five defined aims:

1) Describe the diet of foxes and cats at four sample sites across the south west of Western Australia

2) Compare the diets of cats and foxes

3) Interpret the results in terms of hyperpredation theory

4) Interpret the results in terms of mesopredator release by testing the following predictions: i) there is an overlap in fox and cat diets; and ii) there is evidence of intraguild predation

5) Discuss the likely impact on native West Australian fauna

1) Describe the diet of foxes and cats at four sample sites across the south west of Western Australia

Red Foxes Overall, foxes from Darkan, Katanning, Mount Barker and Boyup Brook had a high degree of overlap

in their summer diets. The present study reveals that foxes in the south west are primarily

consuming numerous anthropogenic food sources, especially those foods associated with

agricultural practices. Foxes consumed livestock, several varieties of crop and fruits, numerous

invertebrates, bird species and commensal rodent species.

Sheep carrion is the major dietary item of foxes from the four south west sample sites. Most carrion

was putrid with few occurrences of fresh sheep and lambs. Foxes at Katanning in the wheatbelt

bioregion, consumed the highest proportion of sheep (64%, in IRI proportions); and Mount Barker foxes in the jarrah forest bioregion, consumed the least (55%, in IRI proportions). The proportion of sheep in fox diets made up an overall average of 63.5% (in IRI proportions), and because many of these stomachs were full, it appears that this resource is readily available in the south west agricultural region. Foxes were culled during the late summer and early autumn months of February to April. During this time, many pastures are bare and lambing begins in only a few regions as autumn approaches. For instance, foxes culled in Darkan during February consumed no lamb, whereas two foxes from Boyup Brook that were culled in April, and consequently during lambing season, consumed the remains of lambs. Lugton (1993) found that there was a seasonal trend to consumption of sheep by foxes in New South Wales, which peaked in the months that had concurrent reductions in rabbit and invertebrate abundances, and during the lambing season. It is a possibility, that foxes in the south west may be consuming mostly sheep carrion because there is very little alternative mammalian prey available in the summer, and because the lambing season has not fully commenced across the south west (Molsher et al., 2000). It is therefore possible that sheep carrion is sustaining foxes through the dry season as, with the exception of the Darkan fox population, over 80% of foxes were in good to very good physical condition. Foxes from Mount

Barker and Katanning were in the best physical condition and consumed carrion in larger volumes than foxes from either Darkan or Boyup Brook.

Red foxes consumed plant matter in large amounts and in the second highest proportion overall

(average of 12%, in IRI proportions). The plants that were considered to be deliberately consumed at all four sample sites included green grass, seeds, wheat, millet, corn and several varieties of fruit

(Darkan 10%, Katanning 12%, Mount Barker 16% and Boyup Brook 10%, in IRI proportions). Although some authors suggest that foxes may gain little nutritional benefit from grass (Saunders et al., 2004),

Lund (1962) proposes that foxes may gain some vitamin C from green grass. Green grass has been

recorded in most Australian and international dietary studies and its ingestion has been attributed

with aiding digestion and dislodging blockages such as bones and feathers (McIntosh, 1963).

Fruits are also plants consumed regularly by foxes (Bayly, 1978; Coman, 1973; Ferrari, 1995;

Lindstrӧm, 1983; Lloyd, 1980); for the sugars and carbohydrates it contains (Cavallini and Lovari,

1991; Contesse et al., 2004; Ferrari, 1995; Juan et al., 2006; Lindstrӧm, 1983). Foxes in the present

study consumed several varieties of fruit which are grown by farmers in the south west, including:

figs, grapes, mulberries and olives, all of which are typically ripe during the summer months (and

therefore available during the sample collection period). Consistent consumption of fruit in late summer is a logical dietary preference (in the absence of protein-rich meat), for improving body condition (through increased fat stores), prior to the autumn breeding season.

In addition to fruit, seeds, corn and cereals were accessed by foxes at all four analysed sample sites.

This may be explained by the trend in the south west to implement supplemental feeding of

domestic stock with grains and seeds towards the end of summer (John et al., 2005). Farmers also store grain produce in silos and barns and foxes may access these stores, as foxes are known to target produce in agricultural matrices (Lloyd, 1980). Many fox stomachs contained large amounts of only these grains, and consequently appear to be accessing an available anthropogenic food source

in summer, for nutritional values or perhaps to supplement live prey (Arthur et al., 2010; Shorrocks

et al., 1998).

The third most important dietary item for foxes from the south west was invertebrates, which made

up between 4% (Katanning) and 12% (Darkan) of the total diet (with an average of 9% overall, in IRI

proportions). The orders that were consumed the most were: Coleoptera (beetles), Orthoptera

(grasshoppers), and Chilopoda (centipedes). Invertebrates were eaten by foxes in 35 out of 36

Australia dietary studies (one study only described mammalian and bird scat remains (Meek and

Triggs, 1998), and are considered by some authors to be an important supplementary food for foxes

(Catling, 1988; Coman, 1973; McIntosh, 1963). Coman (1973) suggests that invertebrates are more

important to foxes in Australia than they are in international studies of the red fox diet. Dell’Arte and

Leonardi (2009) propose that foxes may consume more invertebrates in semi-arid areas to satisfy water and energy requirements. The mass clearing of land in the south west has increased aridity in the area (which may be compounded by climate change (Gibson et al., 2010; Hughs, 2003; Pitman et al., 2004; Prober and Patrick Smith, 2009) and invertebrates would be a logical food source in the absence of other readily available prey during the dry season and leading up to the fox breeding, and winter seasons. Invertebrates may also be an abundant food resource for foxes in Australia because

of the association of both predator and prey with agriculture (e.g. plagues of Orthoptera) (Cavallini

and Lovari, 1991; Prober and Patrick Smith, 2009).

Birds of various species made up 5% of the overall diet of foxes (varying from 2% in Katanning up to

7% in Boyup Brook, in IRI proportions). Foxes are commonly known as poultry thieves (Lloyd, 1980).

Of the 385 foxes that were examined from the four sample sites, only four foxes had consumed domestic chickens (Gallus gallus domesticus), none of which appeared to be carrion. Although chickens were eaten rarely, the bird species that did occur more frequently in fox stomachs were those that are associated with agricultural regions in Western Australia (Appendix 3). The remains

and eggs of Australian ravens (Corvus coronoides), grey currawongs (Strepera versicolour), several

parrots (Australian ringneck parrot, Barnardius semitorquatus, and red-capped parrot,

Purpureicephalus spurious), and a cockatoo species (galah, Kakatoë roseicapilla) were found in 27

fox stomachs. These bird species are considered to be pests by farmers and land-holders across the

south west (D.E.C, 2009c; Mawson, 2007; Rowley, 1983); as parrots are known for the damage they

do to fruit and grain crops, and ravens occur in high numbers in areas with livestock (D.E.C, 2009a;

2009b; D.E.C., 2007; Long, 1984). Birds like the galah, have benefitted dramatically from the provision of permanent watering points and abundant supply of grains on farms (Davies, 1977;

Doneley, 2003). Bird remains were found in a total of 60 fox stomachs. Out of the 45 bird

occurrences in fox stomachs that were able to be identified to species level, dominance of these

native pest species (60%) may reflect their availability in south west habitats as a result of their

successful exploitation of landscape modification. In addition to pest species, one occurrence of

adult emu (Dromaius novae-hollandiae) carrion was recorded in the wheatbelt site (Darkan). The other bird species consumed included: painted quails (Turnix varia), wood ducks (Chenonetta jubata), New Holland honeyeaters (Phylidonyris novaehollandiae) and unidentified quail, honeyeater and dove species. The fact that the majority of the bird species consumed by foxes spend some, or all of their foraging time on the ground may explain why these species occurred more frequently, as they are easier prey for terrestrial foxes (Coman, 1973; D.E.C, 2009a; 2009c). However, the red fox is mainly a crepuscular and nocturnal hunter, which could indicate that predation on these bird species is the result of either scavenging from road kills, pest shoots carried out by farmers, or predation on roosting birds and nests.

Rodents have an historical commensal association with both human habitations and agricultural regions because of the availability of crops and refuse (Newsome, 1969; Saunders and Giles, 1977).

Foxes have been known to predate almost exclusively on rodents when there are plagues in agricultural regions (Ag.Dpt., 2008; Coman, 1973; Croft and Hone, 1978; McIntosh, 1963), however, rodents accounted for a small proportion of the overall fox diet (house mice 4% and black rats 1% in

IRI proportions). According to Dickman (1992), mice preferentially select habitats with denser vegetation to reduce the risk of predation. Whilst mice and rats are certainly associated with agricultural produce (Brown et al., 2004), the conclusion of harvest season at the end of summer may give them cause to increase foraging in vegetation (Newsome, 1969; Ylönen et al., 2002). If foxes are preferentially traversing pastures in search of sheep and/or sheep carrion, then the two species may have inverse distributions, consequently leading to a low proportion of rodents in fox diets.

Many Australian dietary studies have shown that rabbit is the most popular prey of foxes, especially

in agricultural areas (Catling and Burt, 1995; Coman, 1973; McIntosh, 1963; Read and Bowen, 2001).

However, foxes from the south west were found to consume very little rabbit. This was an unusual

finding as rabbits are present throughout the region and typically found in abundance in the south

west agricultural zone (Ag.Dpt., 2003; Williams et al., 1995). Rabbit numbers are however, known to

vary on a local scale according to availability of grazing vegetation; and Williams et al. (1995) states

that towards the end of summer rabbit numbers may be low, as their reproduction is triggered by

rainfall which occurs during winter. Foxes were collected in the south west during late summer to

early autumn (February to April), which may explain the low prevalence of rabbits in fox diets. The

few Australian dietary studies which did not record rabbit as a dietary item in fox diets were carried

out in arid or alpine habitats (Green and Osborne, 1981; Lapidge and Henshall, 2002; Paltridge,

2002). For example Lapidge and Henshall (2002) examined 38 fox stomachs on a pastoral station in

Queensland, and found no evidence of rabbit. Rabbits were scarce in the region as a result of black

soils being inappropriate for warren construction. The authors noted that in the absence of rabbits,

foxes preyed instead on the next available food item, which was kangaroo carrion (Macropus spp.).

Rabbit may therefore comprise a small proportion of the overall south west fox diet because of an

unknown environmental factor such as soil type, or because of a similar seasonal reduction in rabbit

abundance. In response to lower rabbit number, foxes may be consuming the next most available

food (e.g. sheep carrion), during the summer months.

South west red foxes were found to consume native animal taxa in smaller proportions than those which have generally been reported in other Australian dietary studies (excluding birds and invertebrates, native animals made up a combined total of 1.5% of fox diet, by IRI proportions).

The native mammals consumed by foxes included five occurrences of brushtail possums (Trichosurus vulpecula) and one of a single fat-tailed dunnart (Sminthopsis crassicaudata). In addition, four occurrences of mammalian remains were unable to be identified (0.5%, by IRI proportions), but from 77

hair analysis they were judged likely to be native species. Brushtail possums are nocturnal and descend to the ground in order to feed and cross between suitable browse trees (Pickett et al., 2005;

Triggs et al., 1984). How and Hillcox (2000) believe that because of the extent of landscape clearing in the south west bioregions, brushtail possums are increasingly forced to descend to the ground for longer periods in search of food. This makes brushtail possums vulnerable to predation by red foxes that infiltrate habitat fragments (May and Norton, 1996; Pickett et al., 2005). In addition, juvenile possums disperse towards the end of summer (Cown et al., 1996), and may lack knowledge of the threats posed by novel mammalian predators, which may increase the likelihood of juveniles being taken by foxes. Fat-tailed dunnarts are ground dwelling rodent-sized insectivorous marsupials, which are nocturnal foragers and found in open habitats like pasture land and the edges of paddocks

(Menkhorst, 2001). The fat-tailed dunnart is one species of dasyurid that has potentially benefitted from the wide scale land clearance in the south west, as there is evidence that the species has extended its distribution from an isolated population and now occurs throughout the south west region (Morton, 1978). The fat-tailed dunnart’s preference for open habitats and nocturnal activity may therefore bring it into contact with red foxes which utilise pastures and also hunts at night

(Cavallini and Lovari, 1991; 1994).

The reptile species consumed were mostly nocturnal blind-snakes (Ramphotyphlops spp.); diurnal pygopods (Delma spp.); one unknown species of snake and several bobtail lizards (Tiliqua rugosa).

Foxes are nocturnal hunters and may therefore encounter reptile species that are also active at night. Foxes have also been known to be crepuscular (Cavallini and Lovari, 1994; Meek and

Saunders, 2000). In summer the sun sets later and temperatures remain high, as a consequence diurnal reptiles may still be active when foxes begin their hunting activity. In addition to reptiles, foxes consumed numerous entire frogs (Limnodynastes dorsalis; Litoria moorei; Neobatrachus kunapalari; and four unknown species); all of which breed during summer months and call in choruses during the evenings (Bush et al., 2002; Tyler et al., 2000), making them vulnerable to

predation by foxes which have very sensitive hearing. Consumption of these native fauna by red

foxes reflects the predator’s activity period and ability to consume multiple animal taxa as

opportunistic dietary items (items that are eaten occasionally (Newsome et al., 1983) (Glen et al.,

2006a; Paltridge, 2002; Triggs et al., 1984).

Overall, the diet of the red fox in the south west of Western Australia is dominated by sheep carrion

at the end of summer, most likely as a result of widespread agricultural practices. Consumption of

sheep carrion may therefore relieve predation pressure on wildlife in the south west, or

alternatively, it may indicate that fauna are not there in sufficient quantities to support the large red

fox population. Unlike most Australian dietary studies of the red fox, rabbit was not the main food.

Because summer is not rabbit breeding season in the south west, it is assumed that rabbit

consumption was low as a result of rabbit populations being smaller during the summer months.

After sheep carrion, a wide variety of supplemental food including invertebrates and plants was

consumed. The additional opportunistic consumption of native fauna species increased the dietary

breadth of this truly generalist carnivore.

Feral Cats Thirty-nine feral cats from the south west region of Western Australia were found to consume significantly similar diets. Cats ate a wide range of food categories and preyed on native species to a much greater extent than introduced species.

The current study reveals that birds (and bird eggs), and not mammals, are the primary prey of feral cats. Twenty out of twenty-one studies of feral cat diets in Australia records the occurrence of birds in both cat stomachs and scats. Cats are typically known to predate on mammals in preference to other prey types (Dickman, 1996b; Meek and Triggs, 1998), and birds are therefore believed to be supplemental prey (Pearre and Maass, 1998). Birds can however, constitute a greater proportion of the diet of cats living in arid environments (Jones and Coman, 1981). The remains of 14 birds and 3 bird eggs were found in cat stomachs from the four sample sites. Three parrot species (Australian 79

ringneck parrot, red-capped parrot, and regent parrot (Polytelis anthopeplus)) occurred the most frequently. All bird species consumed were either ground-dwelling or ground-foraging (D.E.C, 2009a;

2009b; 2009c; 2009d; D.E.C., 2007; Storr and Johnstone, 1979); which is a trend that was also observed by Catling et al. (1988), who studied cats in ex-grazing land habitat in New South Wales.

Bird remains were found mainly in cats from Darkan and comprised over half of all items consumed

(57% by IRI proportion). By comparison, cats from Mount Barker only consumed an IRI proportion of

10% birds. Mount Barker has not been cleared to the extent that Darkan has been, and the availability of more trees for protection may offer even ground foraging birds, some protection from predators like feral cats. However, cats are not limited to consumption of bird species that are active on the ground, as they are able to climb trees and ingest eggs and altricial young out of nests

(Fitzgerald, 1988; Read and Bowen, 2001). This may explain the discovery of bird eggs in three cat stomachs, although the freshness of the eggs could not be ascertained and may therefore have been scavenged. Although the breeding season for most birds is over by the end of summer, the high incidence of bird remains in stomachs may be a consequence of fledgling dispersal, which may lack the experiential knowledge required to actively avoid cat predation. Whilst it is possible that cats scavenged birds from road kills or pest shoots carried out by farmers, no maggots or putrid bird remains were found in cat stomachs. From analysis of feral cat stomach contents it can be concluded that birds and bird eggs are the staple dietary category of feral cats sampled in the south west. This may have dire implications for native avifauna of the south west.

After birds, deliberately ingested plants made up the highest proportion of foods. Green grass was the main plant eaten and is believed by some authors to be eaten by cats as a laxative; to encourage vomitus; void parasites; and, for trace elements and vitamins (Fitzgerald, 1988). Despite the benefits associated with green grass most published studies regard the ingestion of plant matter by feral cats as incidental to consumption of prey on the ground or in vegetation (Coman and Brunner, 1972; 80

Jones and Coman, 1981). The green grass eaten by cats from the south west was clearly chewed deliberately and was the only item in three stomachs, which suggests deliberate consumption

(though differential digestive times of foods cannot be ruled out as an explanation for the occurrence of only grass in stomachs). In addition to green grass, one cat consumed unidentified fruit and six cats consumed wheat, seeds and corn. This is a surprising discovery as no literature has recorded these items in cat diets. The cats which ate grains were from Boyup Brook, were also in the best physical condition. The deliberate consumption of anthropogenic foods, coupled with a large proportion of green grass in the diet may perhaps indicate that plants are supplementing live prey

(e.g. rabbits) and may be assisting feral cats to maintain good body conditions during the summer months.

House mice and rats (Rattus spp.) are the typical food of feral cats in international studies of diet, due to the feline’s ability to silently stalk and ambush prey (Fitzgerald, 1988; Pearre and Maass,

1998). Whilst introduced rodents were not the staple food of feral cats from the south west, introduced house mice were consumed as the third largest IRI proportion (15%), and black rats made up the fifth largest IRI proportion (7%), of the overall diet. There may be several explanations for the high proportion of rodents in south west cat diets (a combined proportion of 22%, by IRI).

Cats prefer to hunt under vegetative cover and in doing so they may come into contact with rodents which also prefer closed habitats (Dickman, 1992). Another explanation for the high proportion of rodents may be found in the association of both rodents and cats with human populations and agricultural practices (Ag.Dpt., 2008; Fitzgerald, 1988; Pocock et al., 2005). The cats culled for the current study, are believed to be feral, but the extent to which they are independent of humans is unknown. For instance, cats may visit refuse tips to scavenge for food scraps (Denny et al., 2002;

Hutchings, 2003; Short et al., 2002b), and in doing so they may come into contact with rats and mice which also utilise these resource points. Human refuse was found in the stomachs of two cats, which confirms the possibility that cats may be accessing human related resources. Feral cats may also

come into contact with rodents if they live in proximity to human farms (Warner, 1985). Rodents are expected on crop farms (Ylönen et al., 2002), and if cats utilise an area which mice and rats target

(e.g. silos and barns), they may be able to exploit a ready source of prey.

Cats have been directly linked to habitats that support rabbits (e.g. grazing land) due to their exploitation of rabbit warrens as daytime retreats (Jones and Coman, 1982; Read and Bowen, 2001).

Rabbit kittens are reported to be the most important dietary item of feral cats in Australia (Bayly,

1978; Catling, 1988; Coman and Brunner, 1972; Jones and Coman, 1981; Molsher et al., 1999a), as kittens fall into the weight range (10-350grams) that is easily predated on by cats (Catling, 1988;

Fitzgerald, 1988; Paltridge et al., 1997). However, none of the 39 feral cats culled in the south west had rabbits in their stomachs. Rabbits breed in winter (Williams et al., 1995), so it can be assumed that during the sample period most rabbits in the south west would be adults, and this would explain the absence of this prey species in the diet of the feral cats.

In the absence of rabbit in the diet, one might expect there to be a higher proportion of native mammals in the stomachs of feral cats; but out of 39 cat stomachs analysed, there was only one occurrence of native mammal being consumed (and one occurrence of unknown native mammal species). This animal was a fat-tailed dunnart and was consumed by a cat from the wheatbelt region.

Feral cats consumed four species of snake (Parasuta gouldii, Elapognathus coronatus, Echiopsis curta and one unknown species) and one unknown skink species. Consumption of smaller, fast prey like skinks reflects the efficient hunting skills of cats. But the consumption of reptiles is normally opportunistic unless other types of prey are unavailable. For instance, feral cats in resource-poor desert areas of Australia, are found to rely on a wide variety of reptiles (Paltridge, 2002; Read and

Bowen, 2001), including snakes and lizards. Western Australia’s south west is semi-arid and the end of summer sees a general reduction in the availability of resources. Reptiles are a useful opportunistic food source as they are active throughout the warmer months and may still be 82

plentiful if mammalian prey declines. According to Konecny (1987) and Paltridge (2002); consumption of the visceral fat bodies of reptiles provides more kilojoules of energy per gram, compared to mammals. High energy yields would therefore make reptiles a very good source of nutrition in the absence of mammals. However, whether feral cats in the south west are consuming reptiles because of their availability during summer, or because of the relative absence of alternative prey, remains unknown.

No amphibians, brushtail possums or cattle remains were consumed by any feral cats. Brushtail possums were only recorded in one Australian dietary study on cats, even though predation on its smaller relative the ringtail possum (Pseudocheirus peregrinus) (weighing up to 1kg (Menkhorst,

2001), was recorded regularly. Cats generally prey on species which are smaller than themselves

(Pearre and Maass, 1998; Read and Bowen, 2001), and consume only the offspring of larger, more aggressive mammals (Fitzgerald, 1988). An interaction with the larger (up to 5kg (Menkhorst, 2001)

brushtail possum may therefore have a negative outcome for feral cats. By comparison, amphibian species fall into the weight range (10-350grams) that cats tend to target (Fitzgerald, 1988; Pearre and Maass, 1998), and despite evidence for their consumption in nine Australian dietary studies,

cats in the south west did not consume any individuals. This may indicate that cats are not

opportunistically eating frogs, or it may indicate that frogs are rare or absent in the habitat occupied

by the 39 feral cats from the four sample sites.

The feral cats in this study consumed a relatively high IRI proportion of sheep carrion compared to other diet studies carried out in Australia (Martin et al., 1996). Scavenging has been reported in several dietary studies that examined cat diets in resource poor environments, but generally cats are reluctant to take anything but live food (Algar et al., 2007; Lapidge and Henshall, 2002; Short et al.,

2002b). Lapidge and Henshall (2002) noted that even though kangaroo (Macropus spp.) and feral pig

(Sus scrofa) carrion was abundant in a semi-arid region of Queensland, it was not consumed by cats,

whereas live mammalian prey dominated the diet. It was noted during dissections that cats were

very lean with very little, or no, sub-cutaneous or intestinal fat which suggests that feral cats were

nutritionally stressed and more inclined to scavenge carrion. Because cat populations are usually at

their highest during the peak of summer with dispersal finishing by winter (Jones and Coman, 1982);

competition for access to prime resource patches may be especially high at the end of summer

between cats in the south west. As such, they may resort to scavenging to meet their basic dietary

needs. The presence of carrion coupled with a high proportion of deliberately consumed plants in

this study, may therefore be indicative of a general or seasonal food shortage and/or shifting

population dynamics.

Analysis of 39 cat stomachs revealed that feral cats from four sample sites in the south west region

of Western Australia are eating a wide range of prey categories. The dominant food items differ

somewhat from the dietary literature on cats, with birds supplanting mammals as the staple food

category. A large proportion of the feral cat diet was made up by native fauna species. However,

plant matter and carrion were also present in the overall diet, which may suggest that cats are both

scavenging food and actively killing prey during summer.

2) Compare the diets of red foxes and feral cats, and explain any similarities or differences Evidence for competition between foxes and cats is expected to show up in dietary comparisons.

Paltridge (2002) found an 85% dietary overlap between foxes and cats in the Tanami Desert,

Northern Territory, and attributed this to strong competition for limited, seasonally available

resources. The current study revealed an average dietary overlap of only 26% between red foxes and

feral cats at each sample site. A low average overlap between fox and cat diets therefore seems

indicative of weak competition, possibly due to a greater availability of food in the south west 84

compared to the Tanami Desert. When the number of food categories eaten by red foxes and feral cats in the south west were then compared (foxes ate all 15 categories, cats ate 11), cat diets were almost as broad as fox diets. However, the predators were found to rank the food categories in very different orders of importance. The proportions of each category consumed by foxes and cats differed according to both their supplementary, and importantly, their staple food categories. The staple food of foxes was sheep carrion, with invertebrates and plants as the main supplementary foods, whereas birds were the staple prey of cats, and plants and rodents were the main supplementary food categories. Other food categories were additional or opportunistic dietary items

(foods that are occasionally consumed, (Newsome et al., 1983).

Differences between the staple and supplementary prey of foxes and feral cats may be the result of natural variation in the biology of the two species. For instance, foxes and cats vary in their hunting techniques; foxes are olfactory predators, searching prey and carrion out actively. Cats, by contrast, are ambush predators, concealing themselves near places of likely prey activity and pouncing when prey appear (Read and Bowen, 2001; Turner and Meister, 1988). Dietary differences between foxes and cats may also be the result of different nutritional requirements. Canids are known to consume some plant-based foods whereas felids are hypercarnivores and as such are primarily dependent on flesh (Fitzgerald, 1988; Van Valkenburgh, 1988b). This is reflected to some extent in their dentition, with felids possessing blade-like carnassials and canids having a combination of blade-like and flattened grinding carnassials (Bayly, 1978; Jonathan Davies et al., 2007).

Based on anatomical differences between red foxes and feral cats (e.g. dentition), one would expect more plant material in fox diets relative to that found in cat diets. Plant matter was only supplementary dietary intake for foxes in the south west whereas there was a high incidence of deliberately eaten plant matter in the overall cat diet, which was an unexpected result of stomach analyses. Bayly (1978) examined the stomach contents of feral cats in the arid region of Farina,

South Australia, and found that feral cats consumed substantial volumes of vegetation which were 85

twice the volume consumed by red foxes in the same study period. The author notes that samples were collected during a drought period, and although not stipulated, the high prevalence of vegetation in the cat diet may reflect nutritional stress in an unproductive environment. If feral cats are desperately hungry they may well resort to eating plant matter to survive. Nutritional stress may also explain why feral cats from the south west consumed a broad range of dietary categories.

Risbey et al (1999) found that cats on Heirisson Prong consumed a more diverse diet than foxes, and attributed this to differences in the two predator’s supplementary prey following the seasonal decline of their staple food (i.e. rabbits). The high incidence of carrion in the fox diet and the unusual prevalence of plant material (and carrion) in the cat diet may therefore indicate a significant role for supplemental feeding in the ecology of both species during summer months in the south west.

Although the diets of the sampled foxes and cats have little dietary overlap, suggesting weak competition between the two species, scrutinization of competition and dietary literature indicates that competition between predator species is often the combined result of diet, habitat and behavioural factors (Amarasekare, 2006; Berger and Gese, 2007; Fedriani et al., 2000; Glen and

Dickman, 2008; Jones and Barmuta, 1998; Pacala and Roughgarden, 1982). For example, the IRI proportion of native vertebrate fauna consumed by feral cats (43%) from the south west was seven times greater than the IRI proportion of native vertebrate fauna eaten by red foxes (6%). Such a significant difference between fox and cat diets may be the result of predator habitat selectivity.

There is considerable overlap in the distributions of foxes and cats in Australian habitats (Figure 4.1).

However, at the fine scale, some division of space may occur, as there is evidence that foxes and cats prefer different microhabitats (Read and Bowen, 2001). Cats have a greater preference for denser vegetation that provides opportunities for ambush and also shelter from the elements and their own predators (Molsher, 1999b). Whereas foxes are more likely to venture into open areas and exploit a variety of habitats (Lloyd, 1980). If cats are favouring native vegetation fragments for hunting activity this would explain the higher IRI proportion of native fauna in cat diets, as native fauna are known to

occur at higher abundances in native vegetation compared to agricultural habitat (e.g. reptiles and

birds) (Burbidge, 2004; Hobbs, 1993; 2001; May and Norton, 1996; Noss et al., 2006). By comparison, foxes may be preferentially roaming grazing land in order to find areas containing sheep and/or sheep carrion. If the two predators are utilising different habitats for hunting activity then this may explain the differences in their staple dietary items.

Low overlap between red fox and feral cat diets in the south west may also be explained by the type of competition that exists between the two species. Exploitation competition is when one predator species uses resources that deprive another species of that resource. Feral cats from the south west consumed only one eighth of the overall carrion IRI proportion that foxes consumed. If exploitation competition existed between the two species, then this finding would imply that cats are unable to access carrion frequently as foxes are consuming the majority of sheep remains. An additional type

of competition may also exist between foxes and cats in the south west. Interference competition is

when antagonistic interactions between two predator species result in the physical exclusion of one

species from a resource (Glen and Dickman, 2005). Evidence of cat remains has been found in red

fox scats and stomachs in Australia (Coman, 1973; Paltridge, 2002; Risbey et al., 1999), which may indicate intense aggression between the two predators. The threat of physical aggression between foxes and cats may induce modification of normal cat behaviour and result in cats subsequently avoiding those habitats where conflict is anticipated.

Evidence for interference and exploitation competition between red foxes and feral cats comes from

Australian research conducted in habitats which are food limited and where competition for resources is expected to be higher. For example, Molsher (1999b) radio-tracked feral cats and red foxes in an agricultural landscape and found that cats favoured the cover provided by grassland habitats, and avoided contact with foxes (interference competition). Following removal of foxes, feral cat foraging behaviour became bolder, with a correlated increased in carrion consumption

(exploitation competition). If either or both exploitation and interference competition exists 87

between foxes and cats in the south west, then feral cats may be excluded from habitat by foxes,

and consequently restricted to foods outside of these areas (e.g. plants, rodents and birds). This may

in turn explain why red foxes and feral cats in the south west have low and not high dietary overlap.

The red fox and feral cat dietary findings will now be discussed in the context of three main areas of interest which address the final three aims of this thesis: (Aim 3) hyperpredation; (Aim 4) mesopredator release; and, (Aim 5) impacts on native fauna.

3) Interpret the dietary results in terms of hyperpredation The Hyperpredation hypothesis describes the artificial maintenance of high predator populations as

a result of the introduction of a prey species, or the provision of an unlimited resource (Courchamp

et al., 2000). Access to a constant source of nutrition may potentially sustain a larger animal population during a period when conditions would usually kill weaker or excess individuals that are

beyond the support of natural resources (Campbell et al., 2008). With few habitat requirements and

a generalist diet, foxes are adept at exploiting reduced mesic environments, enabling foxes to thrive

in conditions that threaten other more specialist carnivores (Lloyd, 1980; Purvis et al., 2000). The

current study had produced evidence for hyperpredation by foxes on sheep carrion. This

anthropogenic food source is a result of large-scale sheep production in the south west, which has

lead to increased landscape homogeneity (Hobbs, 2001). Foxes are well known for predating sick or

weak lambs in agricultural regions, and for consuming carrion from multiple species (Arthur et al.,

2010; Lugton, 1993; Moberly et al., 2003; Rowley, 1970; Sequeira, 1980). However, the large

contribution of carrion to the diet of 385 red foxes (from four sample sites), suggests that the

resource is readily available in the summer months. The majority of stomachs contained large

volumes of carrion and the foxes did not appear to be nutritionally stressed during the summer

period as their overall body conditions were good (Darkan was an exception), with large fat deposits

clearly evident. The large fox sample size (total of 542 animals) collected in association with the Red

Card for the Red Fox Programme, is a general indication of just how plentiful these predators were, despite the late summer sampling period. If foxes consumed native species alone, the population may be considerably smaller and would presumably reach a point of equilibrium (Jarman and

Johnson, 1977), but each year the culling programme kills thousands of animals and still the population is sustained (D.E.W.H.A., 2008; Saunders and McLeod, 2007). Dietary data is required for annual seasons over multiple years to further explore the potential for hyperpredation by foxes in the south west, but the data from this study indicate that foxes are benefiting from the accidental provision of sheep carrion, and that carrion may sustain them over summer and assist in maintaining artificially large populations.

The feral cats sampled from the south west do not appear to be hyperpredating on any single species. They do, however, appear to be relying on numerous bird species for one third of their dietary intake. Because the protection of native vegetation is rapidly dwindling in the south west, predation on birds by cats could have serious consequences for the region’s avifauna during the summer months. Without seasonal knowledge of feral cat predation rates on birds however, hyperpredation remains just a theory.

4) Interpret the results in terms of mesopredator release by testing the following predictions: i) there is an overlap in fox and cat diets; ii) there is evidence of intraguild predation i) Is there an overlap in fox and cat diets? Interspecific competition will exist if two predator species overlap significantly in one or more of: foods taken, period of activity, techniques used to capture prey or habitats exploited for feeding.

The stronger the similarity between predator species in one or more of these factors, the more likely mesopredator release is to occur (Nally, 1983; Pacala and Roughgarden, 1982; Prugh et al., 2009).

Foxes and cats both preferentially hunt at night, so there is unlikely to be segregation between them based on time of hunting. Both species use different hunting techniques, though both are typical of mammalian predators. However, there does appear to be some segregation between fox and cat diets in the south west, with diets overlapping in only a quarter of total food items (average of 26%).

Low dietary overlap suggests weak competition between the two predators making the phenomenon of mesopredator release unlikely to occur in the south west should foxes continue to be culled at the end of summer. However, exploitation and/or interference competition may be occurring between foxes and cats. If competition is strong, then the possibility of mesopredator release occurring in the south west cannot be discredited, as spatial interactions can affect dietary composition. The extent of feral cat release following removal of foxes may be dramatic if cats have increased access to sheep carrion, as they are capable of reproducing faster than foxes when food is abundant (Case, 2003b; Jones and Coman, 1982). Until the spatial interactions between red foxes and feral cats in south west habitats have been ascertained, mesopredator release cannot be dismissed as an unlikely event following fox control. The likelihood of mesopredator release will therefore only be established with further dietary studies of both predators (in the same habitats and at the same time), and the implementation of removal experiments.

ii) Is there evidence of intraguild predation between red foxes and feral cats? Intraguild predation is believed to be a common outcome of interference competition (Fedriani et al., 2000), and is associated with mesopredator release (Polis et al., 1989; Prugh et al., 2009; Ritchie and Johnson, 2009). There was no evidence of intraguild predation found in the stomachs of either foxes or cats at each of the four sites in the current study. This correlates with the findings of the dietary literature, as evidence for intraguild predation between foxes and cats in Australia appears to be limited (only 3 out of all 57 published studies in Australia). Paltridge (2002) found cat remains in 3.3% of 126 fox scats collected in the Tanami Desert; Coman (1973) found evidence of cat hair in

one fox stomach out of 967 stomachs; and, Risbey et al. (1999) found a small cat’s paw in a fox gut.

While these findings may indicate that intraguild predation occurs, the authors could not discount

the possibility that cats may have been eaten as carrion, especially as the relative habitats were

resource poor, potentially making consumption of cat remains more likely. This would certainly

explain the results of Paltridge (2002) who studied cats and foxes in a resource limited desert habitat

(cannibalism between feral cats was also recorded). Interestingly, no evidence of fox has been found in cat guts or scats in Australian literature, which correlates with the findings of this study. When one considers the large number of fox and cat guts and scats examined in the literature, more evidence supporting intraguild predation may be expected if foxes and cats in Australia regularly consume defeated competitors. It therefore follows that intraguild predation may be an incidental rather than an intentional outcome of aggressive interactions. Mesopredator release of cats can therefore not be assumed to occur when foxes are removed from the environment based on intraguild predation, but nor can mesopredator release be discounted as a possible response to shifting trophic dynamics between red foxes and feral cats.

5) Discuss the likely impact on native West Australian fauna South west Western Australia is one of 25 international biodiversity hotspots, with higher native

species richness, species endemism and level of endangerment than other global habitats (Ceballos

and Ehrlich, 2006). Numerous fauna species are threatened by widespread clearance of native

vegetation (Reid and Fleming, 1992; Saunders, 1989), and also from predation by red foxes and feral cats (Dickman, 1996b; Saunders et al., 1995). Although red foxes consumed a low proportion of native fauna species in the current study, predation on even a single individual of a threatened or range-restricted species can have devastating effects on perseverance of that species (Brunner et al.,

1991; Burbidge and McKenzie, 1989). For instance, foxes which ate amphibians in this study usually ate more than one individual. One fox ate 13 whole frogs of the same species, and another two 91

foxes each consumed eight individuals. In addition to killing to feed, foxes will also surplus kill and cache their prey (Macdonald, 1977; Short et al., 2002a), and this could mean that populations of animals that are not typically fox prey are still at risk from fox predatory activity (Macdonald, 1977).

If high predation rates were maintained seasonally it becomes possible for foxes to cause rapid extinctions.

However, at the end of summer in the south west, foxes are primarily consuming sheep carrion, which may indicate that very little predation on native prey species is occurring. Whether this is because foxes have a preference for carrion over other foods, or whether there is very little alternative prey available in the south west, remains unknown. If hyperpredation on sheep carrion is directly maintaining large fox populations, predation rates on vertebrate species that are not staple items (but which are opportunistic sources of nutrition), may be higher than native fauna populations are able to endure. By unintentionally subsidizing the diet of red foxes with sheep carcasses, humans may be further exaggerating an already critical imbalance between red fox numbers and dwindling native animal populations. If anthropogenic food sources were eliminated from the south west environment, a substantial decrease in fox numbers may be expected to occur.

If competition between foxes and feral cats is actually strong despite the implications of low dietary overlap offered by the current study, then in response to a decrease in fox numbers, feral cat numbers may be released and the impact on fauna species may be larger than the impact of red foxes. For instance, Risbey et al (2000) controlled foxes on Heirisson Prong, Western Australia, after which feral cat numbers increased three-fold, and in response the small mammal captures declined by 80%. The present study revealed that in the south west, feral cats predate on native species more extensively than red foxes, and that cats are capable of taking a broad range of food categories which challenges the ecological definition of cats as hypercarnivores. Because cats tend to hunt under vegetative cover they also have a greater chance of encountering species that are range 92

restricted or which favour vegetation fragments, and like the red fox, could have a dramatic impact

on vertebrate and invertebrate prey populations, even if predation rates were low. Integration of

knowledge about both predators’ ecology in the south west is required, as well as an understanding

of their interactions in the presence and absence of one another. Removal experiments are

therefore necessary to determine the impact that both red foxes and feral cats could have on native

fauna in south west Western Australia.

General Conclusions and Future Recommendations From the results of the present study, dietary competition between red foxes and feral cats in the

south west region of Western Australia appears to be weak towards the end of summer. Analysis of

fox and cat diets has revealed that each species is consuming food categories in different

proportions. Fox diets are dominated by sheep carrion and cats are eating a larger proportion of

native fauna than foxes. If resources are not limiting in the south west, then foxes and cats may

naturally partition resources based on their different ecologies. Alternatively, competition between

the two predators may be so intense that exploitation or interference competition over food may

affect feral cat behavioural (e.g. changes in habitat selectivity), which can result in changes to dietary

composition. During the sampling period, both species were consuming a wide range of native prey

species which makes them a significant threat to the south west’s native fauna. The role that carrion plays in the overall diet of foxes and cats needs to be studied over a longer time period in order to see whether there are seasonal trends, and whether reduction of anthropogenic food sources would

result in a concurrent reduction in local fox and cat populations, and consequently be an important

part of the species’ management in the south west.

If invasive species are to be adequately controlled, knowledge of the competitive interactions

between the predators is needed to help gauge the response of one predator to a decrease in

numbers of another predator. Researchers must recognise that using diet analyses to imply competition between two predators has its limitations as a scientific method, as competition does 93

not only occur between two species as a result of shared resources (e.g. habitat). Because environmental factors like food supply, structure and climate of the landscape, season and activity period can all contribute to the composition of diets (Molsher et al., 2000; Witt, 1980), the intricacies of interactions between red foxes and feral cats are an essential requirement for determining the type and strength of competition and the likelihood of both hyperpredation and mesopredator release occurring in Australian ecosystems. Researchers should therefore employ caution when making assumptions about dietary competition between red foxes and feral cats based on dietary composition alone.

Concurrently researching red fox and feral cat interactions and diet in the future is pivotal to controlling the predators and managing any consequent adverse affects in the south west of

Western Australia, and would potentially have significance for other areas of Australia where foxes and cats live in proximity to one another.

Chapter 6 References

Abbott I. 2002. Origin and spread of the cat, Felis catus, on mainland Australia, with a discussion of the magnitude of its early impact on native fauna. Wildlife Research 29(1):51-74. Abbott I. 2008. The spread of the cat, Felis catus, in Australia: re-examination of the current conceptual model with additional information. Conservation Science of Western Australia 7(1):1-17. Ables ED. 1969. Home-range studies of red foxes (Vulpes vulpes). Journal of Mammalogy 50(1):108- 120. Ag.Dpt. 2003. Farmnote No. 39: European Rabbit. Perth, Western Australia: Department of Agriculture. Ag.Dpt. 2008. Farmnote No. 43: Mice on farms. Perth, Western Australia: Department of Agriculture. 2 p. Alderton D. 1998. Foxes, wolves and wild dogs of the world. New York: Cassell Illustrated. 192 p. Algar D, Angus GJ, Williams MR, Mellican AE. 2007. Influence of bait type, weather and prey abundance on bait uptake by feral cats (Felis catus) on Peron Peninsula, Western Australia. Conservation Science of Western Australia 61:109-149. Allaby M. 2003. Oxford Dictionary of Zoology. Zoology. 3rd ed. Oxford: Oxford University Press. p 581. Amarasekare P. 2006. Productivity, dispersal and the coexistence of intraguild predators and prey. Journal of Theoretical Biology 243(1):121-133. ANRM. 2009. Australian Natural Resources Atlas: Biodiversity Assessment - Avon Wheatbelt. http://wwwanragovau/topics/vegetation/assessment/wa/ibra-avon-wheatbelthtml. Canberra: Department of Environment, Water, Heritage and the Arts. Armstrong G, Booth DT. 2005. Dietary ecology of the Australian freshwater turtle (Elseya sp.: Chelonia: Chelidae) in the Burnett River, Queensland. Wildlife Research 32:349-353. Armstrong JA, Abbott I. 1995. Sustainable conservation- a practical approach to conserving biodiversity in Western Australia. In: Grigg G, Hale P, Lunney D, editors. Conservation Through Sustainable Use Of Wildlife: Centre for Conservation Biology, University of Queensland. p 21-28. Arthur AD, Henry S, Reid A. 2010. Influence of revegetation on predation rates by introduced red foxes (Vulpes vulpes) in south-eastern Australian farmland. Austral Ecology. Australian Government Department of the Environment W, Heritage and the Arts. 2009. Biodiversity Summary for NRM Regions Biodiversity summary for South West WA. Bamford MJ. 1995. Predation by feral cats upon lizards. West Australian Naturalist 20:191-196. Banks PB. 1998. Responses of Australian bush rats, Ratus fuscipes, to the odour of introduced Vulpes vulpes. Journal of Mammalogy 79(4):1260-1264. Banks PB. 1999. Predation by introduced foxes on native bush rats in Australia: do foxes take the doomed surplus? Journal of Applied Ecology 36:1063-1071. Banks PB, Newsome AE, Dickman CR. 2000. Predation by red foxes limits recruitment in populations of eastern grey kangaroos. Austral Ecology 25:283-291. Barratt DG. 1998. Predation by house cats, Felis catus (L.), in Canberra, Australia. II. Factors affecting the amount of prey caught and estimates of the impact on wildlife. Wildlife Research 25(5):475-487. Bayly CP. 1976. Observations on the food of the feral cat (Felis catus) in an arid environment. South Australian Naturalist 51:22-24. Bayly CP. 1978. A comparison of the diets of the red fox and the feral cat in an arid environment. South Australian Naturalist 53:21-28.

Beecham BC. 2003a. Avon Wheatbelt 1 (AW1 – Ancient Drainage Sub-Region). In: A biodiversity audit of Western Australia’s 53 biogeographical subregions in 2002. Department of Conservation and Land Management, Perth, Western Australia. 1-29 p. Beecham BC. 2003b. Avon Wheatbelt 2 (AW2- Rejuvenated Drainage Sub-Region). In: A biodiversity audit of Western Australia’s 53 biogeographical subregions in 2002. Department of Conservation and Land Management, Perth, Western Australia 1-35 p. Berger KM, Conner MM. 2008. Recolonizing wolves and mesopredator suppression of coyotes: impacts on pronghorn population dynamics. Ecological Applications 18(3):599-612. Berger KM, Gese EM. 2007. Does interference competition with wolves limit the distribution and abundance of coyotes? Journal of Animal Ecology 76(6):1075-1085. Blumstein DT, Daniel JC. 2002. Isolation from mammalian predators differentially affects two congeners. Behavioural Ecology 13(5):657-663. Bradstock RA, Williams JE, Gill AM. 2002. Flammable Australia: the fire regimes and biodiversity of a continent. . Cambridge: Cambridge University Press Braysher M. 1993. Managing Vertebrate Pests: Principles and Strategies: Bureau of Resource Sciences. Breed B, Ford F. 2007. Native mice and rats. Collingwood: CSIRO Publishing. 185 p. Brooker MG. 1977. Some notes on the mammalian fauna of the western Nullabor Plain, Western Australia. The West Australian Naturalist 14:2-14. Brooks TM, Mittermeier RA, Mittermeier CG, Da Fonseca GAB, Rylands AB, Konstant WR, Flick P, Pilgrim J, Oldfield S, Magin G, Hilton-Taylor C. 2002. Habitat loss and extinction in the hotspots of biodiversity. Conservation Biology 16(4):909-923. Brothers NP, Skira IJ, Copson GR. 1985. Biology of the Feral Cat, Felis Catus (L.), On Macquarie Island. Wildlife Research 12(3):425-436. Brown GW, Triggs BE. 1990. Diets of wild canids and foxes in East Gippsland 1983-1987, using predator scat analysis. Australian Mammalogy 13:209-213. Brown PR, Davies MJ, Singleton GR, Croft JD. 2004. Can farm-management practices reduce the impact of house mouse populations on crops in an irrigated farming system? Wildlife Research 31(6):597-604. Browning TO. 1977. Processes that contribute to the establishment and success of exotic animal species in Australia. In: Anderson D, editor. Exotic species in Australia- their establishment and success. Adelaide: The Ecological Society of Australia. p 27-38. Brunner H, Coman BJ. 1974. The Identification of Mammalian Hair. Melbourne: Inkata Press Pty Ltd. 176 p. Brunner H, Moro D, Wallis LR, Andrasel A. 1991. Comparison of the diets of foxes, dogs and cats in an urban park. Victorian Naturalist 108:35-37. Brunner H, Triggs B. 2002. Hair ID: An interactive tool for identifying Australian mammal hair. Ecobyte Pty Ltd. Brunner H, Wallis LR. 1986. Roles of predator scat analysis in Australian mammal research. Victorian Naturalist 103:79-87. Burbidge AA. 2004. Threatened animals of Western Australia. Perth: Department of Conservation and Land Management. 201 p. Burbidge AA, Manly BFJ. 2002. Mammal extinctions on Australian islands: causes and conservation implications. Journal of Biogeography 29(4):465-473. Burbidge AA, McKenzie NL. 1989. Patterns in the modern decline of Western Australia's vertebrate fauna: causes and conservation implications. Biological Conservation 50:pp143-198. Burrows ND, Algar D, Robinson AD, Sinagra J, Ward B, Liddelow G. 2003. Controlling introduced predators in the Gibson Desert of Western Australia. Journal of Arid Environments 55(4):691-713.

Bush B, Maryan B, Browne-Cooper R, Robinson D. 2002. A guide to the reptiles and frogs of the Perth region. Hooper K, editor. Perth. 226 p. Campbell NA, Reece JB, Meyers N, Urry LA, Cain ML, Wasserman SA, Minorsky PV, Jackson RB. 2008. Ecosystems. Biology, 8th Edition: Pearson Education Incorporated. p 1246-1269. Case LP. 2003a. Felis sylvestris to Felis catus: Domestication. The Cat: Its behaviour, nutrition and health Ames: Iowa State Press. p 3-11. Case LP. 2003b. Reproduction and breeding management. The Cat: Its behaviour, nutrition and health. Ames: Iowa State Press. p 53-66. Catling PC. 1988. Similarities and contrasts in the diets of foxes, Vulpes vulpes, and cats, Felis catus, relative to fluctuating prey populations and drought. Australian Wildlife Research 15:307- 317. Catling PC, Burt RJ. 1995. Why are red foxes absent from some eucalypt forests in eastern New South Wales? Wildlife Research 22(4):535-545. Cavallini P, Lovari S. 1991. Environmental factors influencing the use of habitat in the red fox, Vulpes vulpes. Journal of Zoology 223(2):323-339. Cavallini P, Lovari S. 1994. Home range, habitat selection and activity of the red fox in a Mediterranean coastal ecotone. Acta Theriologica 39(3):279-287. Cavallini P, Volpi T. 1995. Biases in the analysis of the diet of the red fox Vulpes vulpes. Wildlife Biology 1:243-248. Ceballos G, Ehrlich PR. 2006. Global mammal distributions, biodiversity hotspots, and conservation. Proceedings of the National Academy of Sciences of the United States of America 103(51):19374-19379. Choquenot D, Parkes JP. 2001. Setting thresholds for pest control: how does pest density affect resource viability. Biological Conservation 99:29-46. Christensen P. 1980. A sad day for native fauna. Forest Focus 23:3-12. Christensen P, Burrows ND. 1994. Project desert dreaming: experimental reintroductions of mammals to the Gibson Desert, Western Australia. In: Serena M, editor. Reintroduction Biology of Australian and New Zealand Fauna. Sydney: Surrey Beatty & Sons. p 199-207. Clarke KR, Warwick RM. 2001. Testing for differences between groups of samples. Change in marine communities: an approach to statistical analysis and interpretation. 2nd ed: Primer E Ltd. p 1-14. Coman BJ. 1973. The diet of red foxes, Vulpes vulpes l., in Victoria. Australian Journal of Zoology 21:391-401. Coman BJ, Brunner H. 1972. Food habits of the feral house cat in Victoria. The Journal of Wildlife Management 36(3):848-853. Coman BJ, Robinson J, Beaumont C. 1991. Home range, dispersal and density of red foxes (Vulpes vulpes L.) in central Victoria. Wildlife Research 18(2):215-223. Contesse P, Hegglin D, Gloor S, Bontadina F, Deplazes P. 2004. The diet of urban foxes (Vulpes vulpes) and the availability of anthropogenic food in the city of Zurich, Switzerland. Mammalian Biology 69(2):81-95. Corbett L. 1995. The Dingo in Australia and Asia. Marleston: University of NSW Press. 200 p. Courchamp F, Langlais M, Sugihara G. 2000. Rabbits killing birds: modelling the hyperpredation process. Journal of Animal Ecology 69:154-164. Cowan PE, Tyndale-Biscoe CH. 1997. Australian and New Zealand mammal species considered to be pests or problems. Reproduction, Fertility and Development 9:27-36. Cown PE, Brockie RE, Ward GD, Efford MG. 1996. Long-distance movments of juvenile brushtail possums (Trichosurus vulpecula) on farmland, Hawkes Bay, New Zealand. Wildlife Research 23(2):237-243.

Creel S, Creel NM. 1996. Limitation of African wild dogs by competition with larger carnivores. Conservation Biology 10(2):526-538. Croft JD, Hone LJ. 1978. The stomach contents of foxes, Vulpes vulpes, collected in New South Wales. Australian Wildlife Research 5:85-92. Crooks KR, Soulé ME. 1999. Mesopredator release and avifaunal extinctions in a fragmented system. Nature 400:563-566. D.E.C. 2009a. Fauna Notes No. 16: Australian raven. Perth, Western Australia: Department of Environment and Conservation. 3 p. D.E.C. 2009b. Fauna Notes No. 23: Red-Capped parrot. Perth, Western Australia: Department of Environment and Conservation. D.E.C. 2009c. Fauna Notes No. 21: Galah. Perth, Western Australia: Department of Environment and Conservation. 4 p. D.E.C. 2009d. Fauna Notes No. 27: Wood Duck. Perth, Western Australia: Department of Environment and Conservation. 4 p. D.E.C. 2007. Fauna Note No. 22: Australian Ringneck. Perth, Western Australia: Department of Environment and Conservation. 4 p. D.E.W.H.A. 2008. Background document for the threat abatement plan for predation by the European red fox. Canberra: Department of the Environment, Water, Heritage and the Arts. p 28. Davey C, Sinclair ARE, Pech RP, Arthur AD, Krebs CJ, Newsome AE, Hik D, Molsher R, Allcock K. 2006. Do exotic vertebrates structure the biota of Australia? An experimental test in New South Wales. Ecosystems 9:992-1008. Davies S. 1977. Man's activities and bird's distribution in the Arid Zone. Emu 77(4):169-172. Davis JA, Froend R. 1999. Loss and degradation of wetlands in southwestern Australia: underlying causes, consequences and solutions. Wetlands Ecology and Management 7(1):13-23. Dell'Arte GL, Leonardi G. 2009. The feeding choice of the red fox (Vulpes vulpes) in a semi-arid fragmented landscape of North Africa in relation to water and energy contents of prey. African Journal of Ecology 47(4):729-736. Denny E, Yakovlevich P, Eldridge MDB, Dickman C. 2002. Social and genetic analysis of a population of free-living cats (Felis catus L.) exploiting a resource-rich habitat. Wildlife Research 29(4):405-413. Dexter N, Murray B. 2009. The impact of fox control on the relative abundance of forest mammals in East Gippsland, Victoria. Wildlife Research 36:252-261. Dickman CR. 1992. Predation and habitat shift in the house mouse, Mus Domesticus. Ecology 73(1):313-322. Dickman CR. 1996a. Impact of exotic generalist predators on the native fauna of Australia. Wildlife Biology 2(3):185-195. Dickman CR. 1996b. Overview of the impacts of feral cats on Australian native fauna. Canberra: Australian Nature Conservation Agency. 92 p. Donadio E, Buskirk SW. 2006. Diet, morphology, and interspecific killing in Carnivora. The American Naturalist 167(4):524-536. Doneley B. 2003. The galah. Seminars in Avian and Exotic Pet Medicine 12(4):185-194. Dybing N, Fleming T, Adams P. 2010. Gastro-intestinal parasites of red foxes (Vulpes vulpes) and feral cats (Felis catus) in southwest Western Australia. Unpublished Thesis. Perth: Murdoch University Edwards GP, De Preu N, Crealy IV, Shakeshaft BJ. 2002. Habitat selection by feral cats and dingoes in a semi-arid woodland environment in central Australia. Austral Ecology 27:26-31. Edwards GP, De Preu N, Shakeshaft BJ, Crealy IV, Paltridge RM. 2001. Home range and movements of male feral cats (Felis catus) in a semiarid woodland environment in central Australia. Austral Ecology 26(1):93-101.

Ehrlich PR. 1989. Attributes of invaders and the invading processes: vertebrates. In: Drake JA, editor. Biological Invasions: A Global Perspective: John Wiley & Sons Ltd. Faith D, Minchin P, Belbin L. 1987. Compositional dissimilarity as a robust measure of ecological distance: a theoretical model and computer simulations. Vegetatio 69:57-68. Fascione N, Delach A, Smith ME, editors. 2004. People and Predators- From Conflict to Coexistence. Washington: Island Press. 285 p. Fedriani JM, Fuller TK, Sauvajot RM, York EC. 2000. Competition and intraguild predation among three sympatric carnivores. Oecologia 125(2):258-270. Ferrari N. 1995. Influence of the abundance of food resources on the feeding habits of the red fox, Vulpes vulpes, in western Switzerland. Journal of Zoology 236(1):117-129. Fitzgerald BM. 1988. Diet of domestic cats and their impact on prey populations. In: Turner DC, Bateson P, editors. The domestic cat: the biology of its behaviour. Cambridge: Cambridge University Press. p 221. Gibson L, McNeill A, Tores PD, Wayne A, Yates C. 2010. Will future climate change threaten a range restricted endemic species, the quokka (Setonix brachyurus), in south west Australia? . Biological Conservation 143:2453-2461. Glen A, Dickman CR. 2008. Niche overlap between marsupial and eutherian carnivores: does competition threaten the endangered spotted-tailed quoll? Journal of Applied Ecology 45:700-707. Glen A, Fay AR, Dickman CR. 2006a. Diets of sympatric red foxes Vulpes vulpes and wild dogs Canis lupis in the Northern Rivers Region, New South Wales. Australian Mammalogy 28:101-104. Glen AS, Dickman CR. 2005. Complex interactions among mammalian carnivores in Australia, and their implications for wildlife management. Biological Reviews 80(3):387-401. Glen AS, Dickman CR, Soulé ME, Mackey BG. 2006b. Evaluating the role of the dingo as a trophic regulator. Austral Ecology 32:492-501. Golightly Jr RT. 1997. Coyote (Canis latrans): Ecology, Conservation, and Management. In: Harris JE, Ogan CV, editors. Mesocarnivores of Northern California: Biology, Management, and Survey Techniques. Humboldt State University, Arcata, California. p 127. Green K, Osborne WS. 1981. The diet of foxes, Vulpes vulpes (L.), in relation to abundance of prey above the winter snowline in New South Wales. Australian Wildlife Research 8:349-360. Groom BPK, Froend RH, Mattiske EM. 2000. Impact of groundwater abstraction on a Banksia woodland, Swan Coastal Plain, Western Australia. Ecological Management & Restoration 1(2):117-124. Gullen PJ, Cranston PS, editors. 2010. The Insects: An Outline of Entomology. 4th ed. West Sussex: Wiley-Blackwell Publishing. 242-256 p. Halse SA, Lyons MN, Pinder AM, Shiel RJ. 2004. Biodiversity patterns and their conservation in wetlands of the Western Australian wheatbelt. Records of the Western Australian Museum Supplement No. 67:337-364. Halse SA, Ruprecht JK, Pinder AM. 2003. Salinisation and prospects for biodiversity in rivers and wetlands of south-west Western Australia. Australian Journal of Botany 51(6):673-688. Hammer Ø, Harper DAT, Ryan PD. 2001. PAST: Paleontological Statistics Software Package for Education and Data Analysis. Palaeontologia Electronica 4(1):9. Harris S. 1978. Age determination in the Red fox (Vulpes vulpes)–an evaluation of technique efficiency as applied to a sample of suburban foxes. Journal of Zoology 184(1):91-117. Harris S. 1981. The food of suburban foxes (Vulpes vulpes), with special reference to London. Mammal Review 11(4):151-168. Hart RK, Calver M, Dickman CR. 2002. The Index of Relative Importance: an alternative approach to reducing bias in descriptive studies of animal diets. Wildlife Research 29:415-421. Herbarium WA. 1998. FloraBase: Western Australian flora descriptions by the Western Australian Herbarium http://florabase.dec.wa.gov.au/ Text used with permission

(http://florabase.dec.wa.gov.au/help/copyright). Date of Access: Saturday 05/06/2010. Department of Environment and Conservation. Hobbs RJ. 1993. Effects of landscape fragmentation on ecosystem processes in the Western Australian wheatbelt. Biological Conservation 64(3):193-201. Hobbs RJ. 2001. Synergisms among habitat fragmentation, livestock grazing, and biotic invasions in Southwestern Australia. Conservation Biology 15(6):1522-1528. Hobbs RJ, Cramer VA. 2003. Natural ecosystems: pattern and process in relation to local and landscape diversity in southwestern Australian woodlands. Plant and Soil 257(2):371-378. Hobbs RJ, Mooney HA. 1998. Broadening the extinction debate: population deletions and additions in California and Western Australia. Conservation Biology 12(2):271-283. How RA, Hillcox SJ. 2000. Brushtail possum, Trichosurus vulpecula, populations in south-western Australia: demography, diet and conservation status. Wildlife Research 27(1):81-89. Hughs L. 2003. Climate change and Australia: Trends, projections and impacts. Austral Ecology 28:423-443. Hutchings S. 2003. The diet of feral house cats (Felis catus) at a regional rubbish tip, Victoria. Wildlife Research 30(1):103-110. Hyslop EJ. 1980. Stomach contents analysis- a review of methods and their application. Journal of Fish Biology 17:411-429. Jarman PJ, Johnson KA. 1977. Exotic mammals, indigenous mammals and land-use. In: Anderson D, editor. Exotic species in Australia- their establishment and success. Adelaide: The Ecological Society of Australia. p 146-166. Jarvis NT, editor. 1979. Western Australia: An Atlas of Human Endeavour, 1829-1979. Perth: Western Australian Government. 144 p. John M, Pannell D, Kingwell R. 2005. Climate change and the economics of farm management in the face of land degradation: dryland salinity in Western Australia. Canadian Journal of Agricultural Economics 53(4):443-459. Johnson CN, VanDerWal J. 2009. Evidence that dingoes limit abundance of a mesopredator in eastern Australian forests. Journal of Applied Ecology 46:641-646. Jonathan Davies T, Meiri S, Barraclough TG, Gittleman JL. 2007. Species co-existence and character divergence across carnivores. Ecology Letters 10(2):146-152. Jones E, Coman BJ. 1981. Ecology of the feral cat, Felis catus (L. ), in south-eastern Australia I. Diet. Wildlife Research 8(3):537-547. Jones E, Coman BJ. 1982. Ecology of the feral cat, Felis catus (L.), in south-eastern Australia III. Home ranges and population ecology in semiarid north-west Victoria. Australian Wildlife Research 9(3):409-420. Jones ME, Barmuta LA. 1998. Diet overlap and relative abundance of sympatric dasyurid carnivores: a hypothesis of competition. Journal of Animal Ecology 67(3):410-421. Jones ME, Smith GC, Jones SM. 2004. Is anti-predator behaviour in Tasmanian eastern quolls (Dasyurus viverrinus) effective against introduced predators? Animal Conservation 7(02):155-160. Jose DP, McLean IG, Calver MC. 2002. Recognition of predators by two species of captive-reared peramelids. Australian Mammalogy 24(2):213-218. Juan T, Sagrario A, Jesús H, Cristina CM. 2006. Red fox (Vulpes vulpes L.) favour seed dispersal, germination and seedling survival of Mediterranean Hackberry (Celtis australis L.). Acta Oecologica 30(1):39-45. Jupp J, editor. 2001. The Australian People: An Encyclopedia of the Nation, its People and Their Origins. Cambridge: The Press Syndicate of the University of Cambridge. Kerby G, Macdonald DW. 1988. Cat society and the consequences of colony size. In: Turner DC, Bateson P, editors. The domestic cat: the biology of its behaviour: Cambridge University Press. p 67-81.

100

Kinnear JE, Sumner NR, Onus ML. 2002. The red fox in Australia- an exotic predator turned biocontrol agent. Biological Conservation 108(3):335-359. Kirkwood R, Dann P, Belvedere M. 2005. A comparison of the diets of feral cats Felis catus and red fox Vulpes vulpes on Phillip Island, Victoria. Australian Mammalogy 27:89-93. Konecny MJ. 1987. Food habits and energetics of feral house cats in the Galapagos Islands. Oikos 50:24-32. Lapidge SJ, Henshall S. 2002. Diet of foxes and cats, with evidence of predation on yellow-footed rock wallabies (Petrogale xanthopus celeries) by foxes, in southwestern Queensland. Australian Mammalogy 23:47-52. Lindstrӧm E. 1983. Condition and growth of Red foxes (Vulpes vulpes) in relation to food supply. Journal of Zoology, London 199:117-122. Lloyd HG. 1980. Habitat requirements of the red fox. In: Zimen E, editor. Biogeographica: The Red Fox Symposium on Behaviour and Ecology. The Hague: DR. W. JUNK B.V. Publishers. p 7-25. Lockie JD. 1959. The estimation of the food of foxes. Journal of Wildlife Management 23(2):224-227. Long JL. 1984. The diets of three species of parrots in the south of Western Australia. Wildlife Research 11(2):357-371. Long JL. 2003. Introduced Mammals of the World: Their Histroy, Distribution and Influence. Collingwood: CSIRO Publishing. Lucherini M, Lovari S, Crema G. 1995. Habitat use and ranging behaviour of the red fox (Vulpes vulpes) in a Mediterranean rural area: is shelter availability a key factor? Journal of Zoology 237(4):577-591. Lugton IW. 1993. Diet of red foxes (Vulpes vulpes) in south-west New South Wales, with relevance to lamb predation. Rangeland Journal 15(1):39-47. Lund HM-K. 1962. The red fox in Norway. II. The feeding habits of the red fox in Norway. Meddr St Viltunders 12:3-74. Lunney D, Matthews A, Triggs B. 2002. Long term changes in the mammal fauna of logged, coastal forests near Bega, New South Wales, detected by analysis of dog and fox scats. Australian Mammalogy 23:101-114. Macdonald DW. 1977. On food preference in the red fox. Mammal Review 7(1):7-23. Marlow NJ, Thomson PC, Algar D, Rose K, Kok NE, Sinagra J. 2000. Demographic characteristics and social organisation of a population of red foxes in a rangeland area in Western Australia. Wildlife Research 27:457-464. Martensz PN. 1971. Observations on the food of the fox, Vulpes vulpes (L.), in an arid environment. Wildlife Research 16:73-75. Martin GR, Twigg LE, Robinson DJ. 1996. Comparison of the diet of feral cats from rural and pastoral Western Australia Wildlife Research 23:475-484. Mawson P. 2007. Farmnote No. 125: Parrots and cockatoos in orchards. Perth, Western Australia: Department of Agriculture. p 4. May SA, Norton TW. 1996. Influence of fragmentation and disturbance on the potential impact of feral predators on native fauna in Australian forest ecosystems. Wildlife Research 23:387- 400. McIntosh DL. 1963. Food of the fox in the Canberra District. CSIRO Wildlife Research 8(1):1-20. McKenzie NL, Burbidge AA, Baynes A, Brereton RN, Dickman CR, Gordon G, Gibson LA, Menkhorst PW, Robinson AC, Williams MR, Woinarski JCZ. 2007. Analysis of factors implicated in the recent decline of Australia's mammal fauna. Journal of Biogeography 34(4):597-611. McLean IG, Lundie-Jenkins G, Jarman PJ. 1996. Teaching an endangered mammal to recognise predators. Biological Conservation 75(1):51-62. Meek PD. 2003. Home range of house cats Felis catus living within a National Park. Australian Mammalogy 25:51-60.

101

Meek PD, Saunders G. 2000. Home range and movement of foxes (Vulpes vulpes) in coastal New South Wales, Australia. Wildlife Research 27(6):663-668. Meek PD, Triggs B. 1998. The food of foxes, dogs and cats on two peninsulas in Jervis Bay, New South Wales. Proceedings of the Linnean Society of New South Wales 120:117-127. Menkhorst PW. 2001. A field guide to the mammals of Australia. Meagher D, editor. Melbourne: Oxford University Press. Mitchell D, Williams K, Desmond A. 2003. Swan Coastal Plain 2 (SWA2 – Swan Coastal Plain Sub- Region). In: A biodiversity audit of Western Australia’s 53 biogeographical subregions in 2002. Department of Conservation and Land Management, Perth. Moberly RL, White PCL, Webbon CC, Baker PJ, Harris S. 2003. Factors associated with fox (Vulpes vulpes) predation of lambs in Britain. Wildlife Research 30(3):219-227. Moehlman PD. 1989. Intraspecific variation in canid social systems. In: Gittleman JL, editor. Carnivore behaviour, ecology, and evolution: Cornell University Press. Molsher R, Newsome AE, Dickman CR. 1999a. Feeding ecology and population dynamics of the feral cat (Felis catus) in relation to the availability of prey in central-eastern New South Wales. Wildlife Research 26(5):593 - 607. Molsher RL. 1999b. The ecology of feral cats, Felis catus, in open forest in New South Wales: interactions with food resources and foxes. Sydney: University of Sydney. 271 p. Molsher RL. 2001. Trapping and demographics of feral cats (Felis catus) in central New South Wales. Wildlife Research 28(6):631-636. Molsher RL, Gifford EJ, McIlroy JC. 2000. Temporal, spatial and individual variation in the diet of red foxes (Vulpes vulpes) in central New South Wales. Wildlife Research 27:593-601. Morton SR. 1978. An ecological study of Sminthopsis crassicaudata (Marsupialia : Dasyuridae). I. Distribution, study areas and methods. Australian Wildlife Research 5:151-162. Mukherjee S, Zelcer M, Kotler BP. 2009. Patch use in time and space for a meso-predator in a risky world. Oecologia 159:661-668. Müller CB, Brodeur J. 2002. Intraguild predation in biological control and conservation biology. Biological Control 25(3):216-223. Myers N, Mittermeier RA, Mittermeier CG, da Foncesa GAB, Kents J. 2000. Biodiversity hotspots for conservation priorities. Nature 403:853-858. Nally RCM. 1983. On assessing the significance of interspecific competition to guild structure. Ecology 64(6):1646-1652. Newsome AE. 1969. A population study of house-mice temporarily inhabiting a South Australian wheatfield. Journal of Animal Ecology 38(2):341-359. Newsome AE, Catling PC, Corbett LK. 1983. The feeding ecology of the dingo II. Dietary and numerical relationships with fluctuating prey populations in south-eastern Australia. Austral Ecology 8(4):345-366. Nogales M, Martín A, Tershy BR, Donlan CJ, Veitch D, Puerta N, Wood B, Alonso J. 2004. A review of feral cat eradication on islands. Conservation Biology 18(2):310-319. Noss R, Csuti B, Groom MJ. 2006. Habitat Fragmentation. In: Groom MJ, Meffe GF, Carroll CR, contributors, editors. Principles of Conservation Biology. Massachusetts: Sinauer Associates Inc. Pacala S, Roughgarden J. 1982. Resource partitioning and interspecific competition between two two-species insular Anolis lizard communities. Science 217(4558):444-446. Palomares F, Caro TM. 1999. Interspecific killing among mammalian carnivores. The American Naturalist 153(5):492-508. Paltridge R. 2002. The diets of cats, foxes and dingoes in relation to prey availability in the Tanami Desert, Northern Territory. Wildlife Research 29:389-403. Paltridge R, Gibson D, Edwards G. 1997. Diet of the feral cat (Felis catus) in central Australia. Wildlife Research 24(1):67-76.

102

Parkes JP, Robley A, Forsyth DM, Choquenot D. 2006. Adaptive management experiments in vertebrate pest control in New Zealand and Australia. Wildlife Society Bulletin 34(1):229- 236. Pearre S, Maass R. 1998. Trends in the prey size-based trophic niches of feral and house cats Felis catus L. Mammal Review 28(3):125-139. Pianka ER, Pianka HD. 1976. Comparative ecology of twelve species of nocturnal lizards (Gekkonidae) in the Western Australian desert. Copeia 1:125-142. Pianka L. 1971. Food habits study. Fish Bulletin 152:5-10. Pickett KN, Hik DS, Newsome AE, Pech RP. 2005. The influence of predation risk on foraging behaviour of brushtail possums in Australian woodlands. Wildlife Research 32(2):121-130. Pitman AJ, Narisma GT, Pielke Sr. RA, Holbrook NJ. 2004. Impact of land cover change on the climate of southwest Western Australia. Journal of Geophysical Research 109(D18109):12pp. Pocock MJO, Hauffe HC, Searle JB. 2005. Dispersal in house mice. Biological Journal of the Linnean Society 84(3):565-583. Polis GA. 1988. Exploitation competition and the evolution of interference, cannibalism, and intraguild predation in age/sizestructured populations. In: Ebenman B, Persson L, editors. Size-structured populations. Berlin: Springer. p 185-202. Polis GA, Myers CA, Holt RD. 1989. The ecology and evolution of intraguild predation: potential competitors that eat each other. Annual Review of Ecology and Systematics 20(1):297-330. Prober SM, Patrick Smith F. 2009. Enhancing biodiversity persistence in intensively used agricultural landscapes: a synthesis of 30 years of research in the Western Australian wheatbelt. Agriculture, Ecosystems and Environment 132:173-191. Prugh LR, Stoner CJ, Epps CW, Bean WT, Ripple WJ, Laliberte AS, Brashares JS. 2009. The rise of the mesopredator. BioScience 59:pp 779-791. Purvis A, Gittleman JL, Cowlishaw G, Mace GM. 2000. Predicting extinction risk in declining species. Proceedings of the Royal Society of London B 267:1947-1952. Rayner MJ, Hauber ME, Imber MJ, Stamp RK, Clout MN. 2007. Spatial heterogeneity of mesopredator release within an oceanic island system. Proceedings of the National Academy of Sciences 104(52):20862-20865. Read J, Bowen Z. 2001. Population dynamics, diet and aspects of the biology of feral cats and foxes in arid South Australia. Wildlife Research 28(2):195-203. Reaveley A, Bettink K, Valentine L. 2009. Chapter Eight: Impacts of Introduced Species on Biodiversity. In: Wilson BA, Valentine LE, editors. Biodiversity values and threatening processes of the Gnangara groundwater system. Perth: Department of Environment and Conservation. Reid J, Fleming M. 1992. The conservation status of birds in arid Australia. The Rangeland Journal 14(2):65-91. Risbey DA, Calver MC, Short J. 1999. The impact of cats and foxes on the small vertebrate fauna of Heirisson Prong, Western Australia. I. Exploring potential impact using diet analysis. Wildlife Research 26:621-630. Risbey DA, Calver MC, Short J, Bradley JS, Wright IJ. 2000. The impact of cats and foxes on the small vertebrate fauna of Heirisson Prong, Western Australia. II. A field experiment. Wildlife Research 27:223-235. Ritchie EG, Johnson CN. 2009. Predator interactions, mesopredator release and biodiversity conservation. Ecology Letters 12:pp 982-998. Robley A, Reddiex B, Arthur T, Pech R, Forsyth D. 2004. Interactions between feral cats, foxes, native carnivores, and rabbits in Australia. Melbourne: Arthur Rylah Institute for Environmental Research. 1-76 p. Rolls EG. 1969. They all ran wild. Sydney: Angus & Robertson.

103

Rondganger L. 2010 22/02/10. Shooters take aim at feral foxes to preserve livestock. The West Australian. Rowley I. 1970. Lamb predation in Australia: incidence, predisposing conditions, and the identification of wounds. CSIRO Wildlife Research 15(1):79-123. Rowley I. 1983. Mortality and dispersal of juvenile galahs, Cacatua roseicapilla, in the Western Australian Wheatbelt. Wildlife Research 10(2):329-342. Ruscoe WA, Norbury G, Choquenot D. 2006. Trophic interactions among native and introduced animal species. Biological Invasions in New Zealand: Springer Berlin Heidelberg p247-263. Russell BG, Banks PB. 2007. Do Australian small mammals respond to native and introduced predators? Austral Ecology 32:277-286. Russell JC, Lecomte V, Dumont Y, Le Corre M. 2009. Intraguild predation and mesopredator release effect on long-lived prey. Ecological Modelling 220(8):1098-1104. Salo P, Korpimaki E, Banks PB, Nordstrom M, Dickman CR. 2007. Alien predators are more dangerous than native predators to prey populations. Proceedings of the Royal Society B: Biological Sciences 274(1615):1237-1243. Saunders DA. 1989. Changes in the avifauna of a region, district and remnant as a result of fragmentation of native vegetation: the wheatbelt of Western Australia. A case study Biological Conservation 50(1-4):99-135. Saunders G, Coman BJ, Kinnear JE, Braysher M. 1995. Managing Vertebrate Pests: Foxes. Bomford M, editor. Canberra: Australian Government Publishing. 141 p. Saunders G, McLeod L. 2007. Improving fox management strategies in Australia. Canberra: Bureau of Rural Sciences. Saunders GR, Berghout M, Kay B, Triggs B, van de Ven R, Winstanley RK. 2004. The diet of foxes (Vulpes vulpes) in south-eastern Australia and the potential effects of rabbit haemorrhagic disease. Wildlife Research 31:13-18. Saunders GR, Giles JR. 1977. A relationship between plagues of the house mouse, Mus musculus (Rodentia : Muridae) and prolonged periods of dry weather in south-eastern Australia. Wildlife Research 4(3):241-247. Sequeira DM. 1980. Comparison of the diet of the red fox (Vulpes vulpes L., 1758) in Gelderland (Holland), Denmark and Finnish Lapland. In: Zimen E, editor. Biogeographica: The Red Fox Symposium on Behaviour and Ecology. The Hague: DR. W. JUNK B.V. Publishers. p 35-51. Sergio F, Hiraldo F. 2008. Intraguild predation in raptor assemblages: a review. Ibis 150(s1):132-145. Shedley E. 2007. Fire and Biodiversity Guidelines for the Avon Basin. Perth: Avon Catchment Council and the Department of Environment and Conservation. 1-204 p. Shepherd DP, Beeston GR, Hopkins AJM. 2001. Native Vegetation in Western Australia. Technical Report 249. Department of Agriculture, Western Australia, South Perth. Shorrocks B, Albon S, Kurki S, Nikula ARI, Helle P, Lindén H. 1998. Abundances of red fox and pine marten in relation to the composition of boreal forest landscapes. Journal of Animal Ecology 67(6):874-886. Short J, Kinnear JE, Robley A. 2002a. Surplus killing by introduced predators in Australia- evidence for ineffective anti-predator adaptations in native prey species? Biological Conservation 103(3):283-301. Short J, Smith A. 1994. Mammal decline and recovery in Australia. Journal of Mammalogy 75(2):pp 288-297. Short J, Turner B, Risbey D. 2002b. Control of feral cats for nature conservation. III. Trapping. Wildlife Research 29(5):475-487. Sillero-Zubiri C, Hoffmann M, Macdonald DW, editors. 2004. Canids: Foxes, Wolves, Jackals and Dogs. Status Survey and Conservation Action Plan. Gland, Switzerland: International Union for Conservation of Nature and Natural Resources/Status Survey and Conservation Canid Specialist Group. 443 p.

104

Smith AP, Quin DG. 1996. Patterns and causes of extinction and decline in Australian conilurine rodents. Biological Conservation 77(2-3):243-267. Soulé ME, Bolger DT, Alberts AC, Wrights J, Sorice M, Hill S. 1988. Reconstructed dynamics of rapid extinctions of chaparral-requiring birds in urban habitat islands. Conservation Biology 2(1):75-92. Soulsbury CD, Iossa G, Baker PJ, Harris S. 2008. Environmental variation at the onset of independent foraging affects full-grown body mass in the red fox. Proceedings of the Royal Society B: Biological Sciences 275:2411-2418. Storr GM, Johnstone RE. 1979. Field guide to the birds of Western Australia. Perth: Western Australian Museum. 211 p. Storr GM, Smith LA, Johnstone RE. 1999. Lizards of Western Australia. I Skinks. Watson A, editor. Perth: Western Australian Museum. 291 p. Storr GM, Smith LA, Johnstone RE. 2002. Snakes of Western Australia. Perth: Western Australian Museum. 309 p. Strahan R, editor. 1999. The Australian Museum Complete Book of Australian Mammals: The National Photographic Index of Australian Wildlife. North Ryde: Cornstalk Publishing. 530 p. Switalski TA. 2003. Coyote foraging ecology and vigilance in response to gray wolf reintroduction in Yellowstone National Park. Canadian Journal of Zoology 81:985-993. Terborgh J, Lopez L, Nunez P, Rao M, Shahabuddin G, Orihuela G, Riveros M, Ascanio R, Adler GH, Lambert TD, Balbas L. 2001. Ecological meltdown in predator-free forest fragments. Science 294(5548):1923-1926. Tidemann C. Do cats impact on wildlife?; 1994; Canberra. p 1-5. Triggs B. 2003. Tracks, scats and other traces: a field guide to Australian mammals. Meagher D, editor. Melbourne: Oxford University Press. 340 p. Triggs B, Brunner H, Cullen JM. 1984. The food of fox, dog and cat in Croajingalong National Park, south-eastern Victoria. Wildlife Research 11(3):491-499. Turner DC, Meister O. 1988. Hunting behaviour of the domestic cat. In: Turner DC, Bateson P, editors. The Domestic Cat: the biology of its behaviour. Cambridge: Cambridge University Press. p 111-121. Tyler MJ, Smith LA, Johnstone RE. 2000. Frogs of Western Australia. Perth: Western Australian Museum. 195 p. Van Valkenburgh B. 1988b. Trophic diversity in past and present guilds of large predatory mammals. Paleobiology 14:155-173. von Schantz T. 1981. Female cooperation, male competition, and dispersal in the red fox Vulpes Vulpes. Oikos 37(1):63-68. Wallach AD, Murray BR, O'Neill AJ. 2009. Can threatened species survive where the top predator is absent? Biological Conservation 142(1):43-52. Wardell-Johnson G, Horwitz P. 2009. The Science of Conservation Biology. In: Calver M, Lymbery A, McComb J, Bamford M, editors. Environmental Biology. Cambridge: Cambridge University Press. Warner RE. 1985. Demography and movements of free-ranging domestic cats in rural Illinois. Journal of Wildlife Management 49(2):340-346. Wayne AF, Cowling A, Lindenmayer DB, Ward CG, Velios CV, Donnelly CF, Calver MC. 2006. The abundance of a threatened arboreal marsupial in relation to anthropogenic disturbances at local and landscape scales in Mediterranean-type forests in south-western Australia. Biological Conservation 127:463-476. West P. 2008. Assessing Invasive Animals in Australia Canberra: National Land & Water Resources Audit and Invasive Animals CRC. 98 p. White JG, Gubiani R, Smallman N, Snell K, Morton A. 2006. Home range, habitat selection and diet of foxes (Vulpes vulpes) in a semi-urban riparian environment. Wildlife Research 33(3):175-180.

105

Williams K, Mitchell D. 2003. Jarrah Forest 1 ( JF1 – Northern Jarrah Forest Sub-Region). In: A biodiversity audit of Western Australia’s 53 biogeographical subregions in 2002. Department of Conservation and Land Management, Perth, Western Australia. Williams K, Parer I, Coman BJ, Burley J, Braysher M. 1995. Managing Vertebrate Pests: Rabbits. Bomford M, editor. Canberra: Australian Government Publishing Service. Witt H. 1980. The diet of the red fox: questions about method. In: Zimen E, editor. Biogeographica: The Red Fox Symposium on Behaviour and Ecology. The Hague: DR. W. Junk B.V. Publishers. Woolley PA, Craik JA, Grossek GL. 1985. Food of introduced mammalian predators in two Victorian National Parks. Proceedings of the Royal Society of Victoria 97(3):151-155. Ylönen H, Jacob J, Davies MJ, Singleton GR. 2002. Predation risk and habitat selection of Australian house mice , Mus domesticus, during an incipient plague: desperate behaviour due to food depletion. Oikos 99(2):284-289. Zavaleta ES, Hobbs RJ, Mooney HA. 2001. Viewing invasive species removal in a whole-ecosystem context. TRENDS in Ecology & Evolution 16(8):454-459. Zimen E. 1984. Long range movements of the red fox, Vulpes vulpes L. Acta Zoologica Fennica.

106

Appendices

Appendix 1 – Feral Species Collection Card

Appendix 1: Hunters were asked to provide data on the location and habitat in which each red fox or feral cat was culled. Animals were then given a number, sexed and physical measurements were taken, including total body weight and length. Body condition (BC) and coat condition (CC), were given subjective scores and any unusual features were also noted.

107

Appendix 2 – Diagram of Subjective Body Condition Scores

Appendix 2: A subjective assessment of red fox and feral cat body condition was made using subcutaneous and abdominal fat as indicators. A score of 1 was given to foxes and cats with little to no fat. A score of 2 indicated that the animal had a moderate amount of fat; and a score of 3 was given to those animals with a significant fat deposits. The condition of fur coats was also scored in this way to indicate overall health of the predators.

108

Appendix 3 – List of Fauna Species Identified at Four Sample Sites

Location Sample # Class Common Name Species Name Fox Cat

Darkan DA1-DA180 Mammals Sheep Ovis aries   (Introduced) Rabbit Oryctolagus cuniculus  House mouse Mus musculus   Black rat Rattus rattus  Mammals Brushtail possum Trichosurus vulpecular  (Native) Unknown sp. ? 

Birds Twenty-eight parrot Barnardius semitorquatus   (Native) Red-capped parrot Purpureicephalus spurius   Regent parrot Polytelis anthopeplus  New holland honeyeater Phylidonyris novaehollandiae  Galah Kakatoë roseicapilla  Australian raven Corvus coronoides  Grey currawong Strepera versicolor  Australian emu Dromaius novae-hollandiae  Unknown parrot spp. Platycercus spp.  (Introduced) Domestic chicken Gallus gallus domesticus 

Reptiles Bobtail lizard Tiliqua rugosa  Southern blind snake Ramphotyphlops australis  Unknown blind snake spp. Ramphotyphlops spp.  Unknown skink sp. ?  Unknown reptile spp. ? 

Amphibians Unknown frog spp. ? 

Location Sample # Class Common Name Species Name Fox Cat

109

Katanning 20-153 Mammals Sheep Ovis aries   (Introduced) Cattle Bos taurus  Rabbit Oryctolagus cuniculus  Black rat Rattus rattus  House mouse Mus musculus   Mammals Brushtail possum Trichosurus vulpecula  (Native) Fat-tailed dunnart Sminthopsis crassicaudata  Unknown sp. ?  

Birds Twenty-eight parrot Barnardius semitorquatus   (Native) Red-capped parrot Purpureicephalus spurius   Australian raven Corvus coronoides  Grey currawong Strepera versicolor  Galah Kakatoë roseicapilla  Wood duck Chenonetta jubata   Painted quail Turnix varia  Unknown Quail spp. Phasianidae spp.  Unknown Dove spp. Columbidae spp.  Unknown Honey eater spp. Phylidonyris spp.   Unknown Parrot spp. Platycercus spp.  (Introduced) Domestic chicken Gallus gallus domesticus 

Reptiles Gould's snake Parasuta gouldii   Bobtail lizard Tiliqua rugosa  Unknown Snake sp. ?  Unknown Reptile sp. ? 

Amphibians Western banjo frog Limnodynastes dorsalis 

Mount Barker 154-219 Mammals Sheep Ovis aries  (Introduced) Black rat Rattus rattus   House mouse Mus musculus   Unknown sp. ? 

Birds Twenty-eight parrot Barnardius semitorquatus   (Native) Red-capped parrot Purpureicephalus spurius  Australian raven Corvus coronoides  Unknown Honey eater spp. Phylidonyris spp.  Unknown Quail spp. Phasianidae spp.  Unknown spp. ?  (Introduced) Domestic chicken Gallus gallus domesticus 

Reptiles Crown snake Elapognathus coronatus  Bardick snake Echiopsis curta  Unknown spp. ?   Amphibians Burrowing frog ? 

110

Location Sample # Class Common Name Species Name Fox Cat

Boyup Brook 265- 341 Mammals Sheep Ovis aries   (Introduced) Rabbit Oryctolagus cuniculus  House mouse Mus musculus   Mammals Brushtail possum Trichosurus vulpecula  (Native) Unknown sp. ? 

Birds Twenty -eight parrot Barnardius semitorquatus  (Native) Galah Kakatoë roseicapilla  Wood duck Chenonetta jubata  Australian raven Corvus coronoides  Willie wagtail Rhipidura leucophrys  Unknown Honey eater spp. Phylidonyris spp.  Unknown Parrot spp. Platycercus spp.  Unknown Dove spp. Columbidae spp.  Unknown sp. ? 

Amphibians Motorbike frog Litoria moorei 

All Locations Invertebrates Invertebrate Common Name Invertebrate Orders Fox Cat DA1-DA180 Insects Cockroaches Blattodea  Beetles Coleoptera   Flies/Maggots Diptera  True bugs Hemiptera  20-153 Slaters Isopoda  Moths Lepidoptera   Caterpillars Lepidoptera  Two-winged fliers Odonata  154-219 Crickets Orthoptera   Grasshoppers Orthoptera   Chilopoda Centipedes Chilopoda  Oligochaetes Earthworms Oligochaetes  265-341 Arachnids Spiders Araneae   Scorpions Scorpiones  Malacostraca Yabbies Decapoda 

111