Gethin Pugh & Dr David Lee 16032454 University of South Wales

Are African Elephants having a negative impact on the ability for bird species to nest in Selati Game Reserve, South Africa.

African Bush Elephant (Loxodonta africana) Image by Gethin Pugh, 2017

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Table of Contents 1.0. Abstract 4 2.0. Acknowledgements 5 3.0. Introduction 5 4.0. Methodology 10 4.1. Study Site 10 4.2. Data Collection Methods 12 4.3. Statistical Analysis 14 5.0. Results 17 6.0. Discussion 29 7.0. Closing Remarks 37 8.0. References 38 9.0. Appendices 44

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Figures List Figure 1: Location of Selati Game Reserve via Google Map Imagery 11 Figure 2: Preliminary Vegetation Map 12 Figure 3: Chloropleth map displaying recorded elephant damage per plot 19 Figure 4: BEST analysis 25 Figure 5: Species level RELATE analysis 26 Figure 6: Guild level RELATE analysis 26 Figure 7: Species level cladogram 44 Figure 8: Species level cladogram showing groupings 44 Figure 9: Species level cladogram with only elephant damaged plots 45 Figure 10: Habitat type species level Sample Matrix 45 Figure 11: Elephant Damage species level Sample Matrix 46 Figure 12: Species level elephant damage ANOSIM 46 Figure 13: Species level habitat ANOSIM 47 Figure 14: Tree species level cladogram 47 Figure 15: Tree species Sample Matrix 48 Figure 16: Tree habitat ANOSIM 48 Figure 17: Tree elephant damage ANOSIM 49 Figure 18: Guild level cladogram 49 Figure 19: Guild level cladogram showing groupings 50 Figure 20: Habitat type guild level Sample Matrix 50 Figure 21: Elephant Damage guild level Sample Matrix 51 Figure 22: Guild level habitat ANOSIM 51 Figure 23: Guild level elephant damage ANOSIM 52 Tables List: Table 1: Plot and Nest Numbers 18 Table 2: Number of bird and elephant damage plots per habitat 19 Table 3: SIMPER dissimilarity on a species level 21 Table 4: SIMPER similarity on a species level 22 Table 5: SIMPER dissimilarity on a guild level 23 Table 6: SIMPER similarity on a guild level 24 Table 7: Species nest potential and number of nesting trees damaged 28 Table 8: Guild nest potential and number of nesting trees damaged 29

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1.0. Abstract African Bush Elephants (Loxodonta africana) are a major keystone species within savannah ecosystems due to their ability to change the vegetation structure and species communities around them. African bush elephants have the potential to negatively impact bird communities through changing the vegetation structure and damaging trees, which decreases the amount of suitable nesting sites for a whole variety of bird species. Birds are just as relevant to their respective ecosystems as are elephants, occupying key ecological niches and roles, however birds are generally overlooked. Similar to elephants, birds such as granivores and frugivores can act as seed dispersers whilst insectivore bird species can act as insect controllers demonstrating that both birds and elephants can influence the survival of woody plant species through differing feeding behaviours. The effects of elephants modifying vegetation levels on other wildlife species has been barely studied. No previous studies have focused entirely on the impact African elephants have on multiple bird species to nest, rather just focusing their studies on individual species, groups of species or the impact elephants have on the overall bird communities. The aim of this study is to gain an understanding on how African elephants are affecting the nesting potential of the overall bird community of Selati Game Reserve. 2250 individual birds of 95 species were recorded over the five-week survey period as well as 42 tree species were recorded, with 151 bird plots surveyed and 74 elephant damage plots being surveyed respectively. Whilst completing the elephant impact plots 3376 trees were surveyed and a total of 33 nests were found of these 33, five were active. The majority of nests were located within knobthron, Senegalia nigrescens (33.33%), mopane, Colophospherum mopane (27.27%) and red bush willow, Combretum appiculatum (15.15%) trees. Five nests were found within areas of low elephant damage, 6 nests were found in areas of medium damage, 21 nests were found in areas of high elephant damage and 2 nests were found in areas of very high elephant damage. Based on the results of this investigation both of the predicted hypotheses in terms of guild occurrence, were incorrect and in fact there was no change in the abundance of canopy nesters and ground nesters over a changing elephant gradient. It can be concluded based on the findings of the results that African bush elephants are having little to no impact on the ability for birds to nest on both a species and a guild level within Selati Game Reserve. Elephant conservation however is still important due to the decreasing numbers of elephants in other parts of their range,

4 nonetheless, this should not seize the conservation of birds, especially with the heavy decrease seen in many bird species across much of Sub-Saharan Africa.

2.0. Acknowledgements I would like to thank Selati Game Reserve for allowing me to complete my research at their reserve, as well as to Steven Seager the lead researcher at the reserve, who helped greatly with both tree and bird identification on the field. I would further like to acknowledge all the volunteers who helped with data collection with elephant impact plots. These researchers include, Lisa Sampson, Steven Seager, Tom Jinks, Tom Deakin, Yens Vandenboer, Janne Teerlinck, Charlie Collier and Harriet Redgard.

3.0. Introduction African Bush Elephants (Loxodonta africana) are a major keystone species within savannah ecosystems (Jenamiso et al 2015; Reardon 2012) due to their ability to change the vegetation structure (Shannon et al 2011; Jenamiso et al 2015; Mograbi et al 2017; Reardon 2012; Williams 2017) and species communities around them (Reardon 2012). Elephants are classed as being one of a small number of biotic factors that can rapidly modify savannah habitats (Derham et al 2016). This change to savannah ecosystems brought about by elephants can be both positive to some species but negative to others. African bush elephants have the potential to negatively impact bird communities through changing the vegetation structure and damaging trees (Cumming et al 1997; Herremans 1995; Rushworth et al 2018; Vogel et al 2014), which decreases the amount of suitable nesting sites for a whole variety of bird species. However, this impact of change varies on a species to species level, as tree feeling can be a detriment to canopy and trunk nesters (Henley & Henley 2005; Rushworth et al 2014; Vogel et al 2014) through reducing possible nesting sites, whilst on the other hand, high impact areas can be of use to ground nesting bird species as these heavily impacted habitats provides appropriate cover plus some expanses of open ground (Stokke et al 2014; Wolff et al 2002) allowing ground nesters a greater area to forage within. Birds also require a diverse vegetation structure (Skwono & Bond 2003) which can be reduced by elephants, as they are selective feeders, preferring certain species

5 of trees over others (Henley and Henley 2005; Stokke & du Toit 2000), such as Marullas (Sclerocarya birrea) (Cook et al 2017; Cook et al 2018; Cook & Henley 2019; Gadd 2002; Seloana et al 2017) and Mopane (Colophosphorum mopane) trees (Codron et al 2006; Kos et al 2012; Midgley et al 2005). During the drier winter periods, evidence suggests the diet of elephants is largely mopane trees (Kos et al 2012). However, each individual elephant has a specific dietary preference (Kos et al 2012), thus suggesting tree felling rates for food purposes will vary between elephant populations greatly. Due to the wide range of impacts both positive and negative it is difficult to determine whether elephants can be detrimental to bird species and to their ability to nest. Some studies such as the one conducted by Ogada et al (2008) found that native large African herbivores such as elephants, decreased bird abundance and species richness significantly and megaherbivores such as elephants appeared responsible for the decrease in bird species richness. They also noted that bird activity was also reduced in study plots where megaherbivores were present, as well as the fact that no species of bird was more abundant in sample plots that contained megaherbivores. However, Ogada et al (2008) did not conduct any data collection of large mammal or elephant impact on bird nesting only species richness and abundances. When feeding, elephants also browse on the tree canopies and Ogada et al (2008) discovered that both the mean canopy area and the total canopy area of trees were lower within the plots that contained megaherbivores. This can be detrimental to canopy nesters such as raptors and turacos to name a few, which require these large canopies and branches to construct the nests within (Carnaby 2013; Vogel et al 2014). This reduction in canopy area through browsing and less so tree felling can also reduce the number of perching sites (Ogada et al 2008) for certain species. This felling of trees can impact negatively on insectivorous species such as rollers (Coracias and Eurystomus spp) which require perching sites for feeding (Fry & Fry 2010). Having trees with larger and denser canopies can provide smaller birds with safe areas to hide and to escape predation (Ogada et al 2008), however safety and protection can also be offered from tress with dense canopies that have been felled by elephants. Canopy reduction can also lower food availability for birds (Ogada et al 2008). This indirect impact of elephants can alter the species composition and biomass of arboreal insects (Ogada et al 2008) as well as reducing fruit abundance on fruiting trees (Ogada et al 2008). The results by Ogada et al (2008) also correlated with another study

6 conducted by Moe et al (2017) which both concluded that large herbivores such as elephants can reduce bird abundance, richness and diversity. It has also been noted that relatively high densities of elephants above 0.42 elephants per km2, appear to decrease bird diversity (Ogada et al 2008). As well as reducing canopy cover elephants and large mammal browsers alike can directly affect the woody debris abundance and tree species composition through very selective feeding (Kerley & Landman 2006; Codron et al 2014; Moe et al 2017; Seloana et al 2017), with around 6-8 plant species making up 70-80% of their diet (Henley & Henley 2005) elephants are very selective in their feeding habits and may even avoid certain species entirely (Seloana et al 2017). Being highly selective feeders (Derham et al 2016; Shannon et al 2011; Reardon 2012), elephants can change their diet depending on season or by certain environmental conditions (Codron et al 2006; Kos et al 2012; Reardon 2012; Shannon et al 2011). For example, elephants are generally grazers and prefer grasses over woody plant material, with grasses contributing to the majority of their diet during the wet season (Codron et al 2006; Kos et al 2012; Reardon 2012) when it is more readily available. However, elephants can change to browse during the drier winter months (Shannon et al 2011; Kos et al 2012, Reardon 2012, Stokke & du Toit 2000) when grass is less readily available, thus leaving certain tree species vulnerable (Derham et al 2016) during the dry season in areas of high elephant density, especially in times of drought, which Sealti Game reserve is currently under. It can thus be implied that more trees are felled by elephants in the dry season. Differences between the feeding behaviours of cow and bull elephants has also been documented (Henley & Henley 2005; Stokke & du Toit 2000). Elephant bulls tend to have the least diverse diets of the two sexes (Stokke & du Toit 2000) and bulls also fell more trees (Cook et al 2018, Midgley et al 2005, Henley & Henley 2005), up to three times as much as females (Reardon 2012) thus having a greater impact on the vegetation structure of savannah habitats (Henley & Henley 2005). It is believed that bull elephants also push over trees for building confidence and muscle mass (Cook et al 2018, Midgley et al 2005). Not only are elephants very selective feeders but also very unique feeders, being able to use their trunk to pull of leaves and branches as well as acutely pick up favoured grasses (Boundja & Midgley 2010). Elephants also use their tusks to debark trees and dig up roots (Boundja & Midgley 2010) and their own body strength in order to fell trees (Henley & Henley 2005; Reardon 2012). This allows elephants to gain different

7 nutrients from different parts of trees (Boundja & Midgley 2010; Stokke & du Toit 2000; Seloana et al 2017). Trees with high levels of elements such as calcium, magnesium and potassium are also favoured and chosen more by elephants (Holdo 2003). Elephants could also indirectly reduce the food availability for insectivorous bird species through the elephants feeding of herbaceous plants (Ogada et al 2008) thus decreasing the number of ground-dwelling arthropods that require these plants as a source of food (Ogada et al 2008). This overall reduction in food availability could possibly lead to birds not using these areas of high elephant damage for nesting areas due to there being less plentiful food sources available for the chicks once they have hatched. This could possibly lead to greater levels of both intra-specific and inter- specific competition between species of similar foraging guilds. On the other hand, elephants can provide food for certain bird species via their dung (Stokke et al 2014). It has been well documented that gallinaceous bird species feed on the insects such as termites as well as seeds that are found within elephant dung (Jenamiso et al 2015; Stokke et al 2014), as seeds from woody tree species were documented to be present in nine out of ten elephant dung-heaps (Reardon 2012) thus providing plenty of food for these gallinaceous species. Botswana has the highest African elephant population in the world (Herremans 1995; Jenamiso et al 2015; Stokke et al 2014) and is a prime example of how large densities of elephants can heavily impact on the vegetation and thus the bird communities around them. A study by Jenamiso et al (2015) conducted bird surveys along the Chobe Riverfront in Botswana which is known for its high elephant density and large areas of heavily elephant damaged landscapes. They concluded that bird diversity was low in areas of high elephant density, whilst bird diversity remained higher in areas of low and medium elephant densities (Jenamiso et al 2015), implying that the areas of higher elephant density also have a greater number of damaged trees. However, it must be noted that high elephant damage does not negatively affect all species in all habitats. For example, another study conducted within the Chobe National Park on gallinaceous bird species by Stokke et al (2014) discovered that certain gallinaceous species such as helmeted guineafowl (Numida meleagris) and Swainsons’ spurfowl (Pternistis swainsonii) prefer areas of greater elephant damage and less vertical cover, in other words standing trees, due to the combination of dense cover and open areas created by elephants, and that there was a positive correlation between habitat selection of the four studied gallinaceous bird species and high

8 elephant impact areas (Stokke et al 2014). Long-term elephant damage has thus proved beneficial to the studied species of gallinaceous birds in the Chobe National Park (Stokke et al 2014) through providing the needed mosaic of vegetation types, with a mixture of dense cover for hiding (Sande et al 2001) and open areas for feeding (Wolff et al 2002). As well as elephants, birds are just as important to their respective ecosystems (Sekercioglu 2006; Ogada et al 2008), occupying key ecological niches and roles, however birds are generally overlooked. Just like elephants (Kerley & Landman 2006; Reardon 2012) birds such as granivores and frugivores can act as seed dispersers (Sekercioglu 2006; Ogada et al 2008; Moe et al 2017) whilst insectivore bird species can act as insect controllers (Sekercioglu 2006; Ogada et al 2008) showing that both birds and elephants can influence the survival of woody plant species through differing feeding behaviours. Birds also play an important role in the food chain (Ogada et al 2008), as small passerines and columbidaes make up the diet of larger bird (Ogada et al 2008). Within Southern Africa, 964 species of bird have been recorded (Sinclair 2014) either as a resident, migrant or rare vagrant, with 280 species being recorded at the chosen study site (Selati Game Reserve 2018) for this project. The effects of elephants modifying vegetation levels on other wildlife species has been barely studied (Jenamiso et al 2015) and no previous studies have focused entirely on the impact African elephants have on multiple bird species to nest, rather just focusing their studies on individual species, groups of species (Henley & Henley 2005; Monadiem and Garcelon 2005; Vogel et al 2014; Rushworth 2018), or the impact elephants have on the overall bird communities (Herremans 1995; Jenamiso et al 2015; Reardon 2012; Stokke et al 2014; Williams et al 2017) with many of these studies estimating and calculating that elephants can have negative impacts on avian diversity (Jenamiso et al 2015; Ogada et al 2008) while others have not (Herremans 1995; Reardon 2012; Williams et al 2017). The aim of this study is to gain an understanding on how African elephants are affecting the nesting potential of the overall bird community of Selati Game Reserve rather than individual species through conducting bird, nest and elephant impact surveys in the multiple habitats and elephant impacted areas found within the reserve. The first hypothesis of this study is that in areas of higher elephant impact there will be fewer canopy nesting species such as cavity and stick platform nesters, and the second hypothesis will be in areas of higher elephant damage there will be a

9 greater number of scrape nesters. This along with data on nesting potential will allow for nesting impact to be measured. The final hypothesis for this study is that over 75% of trees that can be used for bird nesting will be damaged.

4.0. Methodology 4.1. Study Site The chosen study site selected for this investigation was Selati Game Reserve. Selati Game Reserve is a private game reserve, located in north east South Africa within the Limpopo province within the Lowveld region and savannah biome (Figure 1). Selati Game Reserve is 27,000 hectares in size and Summer temperatures can reach as high as 330C, whilst in winter temperatures can fall as low as 90C. The data collection was completed over five weeks between August and September 2018, which is the dry/winter season in South Africa. The dry season lasts between late May to early September and the wet/summer season begins in mid-September and ends around late April. The reserve receives an average of 530mm of precipitation in a year but is in the fourth year of a drought period with lower than average rainfall in the summer months. The reserve is located around 40 miles to the east of The Greater Limpopo Transfrontier Park that contains Kruger National Park (Reardon 2012). As of August 2018, Selati has a population of 114 African bush elephants (Loxodonta africana) with an average density of 1 elephant per 0.42km2. The elephants of Selati are unable to disperse outside of Selati’s boundaries due the construction of a fence around the reserve. This as well as a low demand for elephants within Southern Africa, has created the relatively high elephant density found within Selati Game Reserve as mentioned above.

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Figure 1: The location of Selati Game Reserve (red marker) relevant too Southern African countries, main cities and reserves via the use of Google Earth (2018).

Selati is split into 11 main vegetation types, as seen on figure 2. The dominant tree species that occur over the majority of the reserve are Mopane (Colophospermum mopane) and Red bush willow (Combretum appiculatum) trees. Each habitat will be surveyed thoroughly using the methods discussed within the data collection methods section. The most dominant habitat found within the reserve, according to figure 2 is habitat five, Colophosphorum mopane, Combretum apiculatum and Acacia spp mixed woodland, closely followed by habitat type four, Colophosphorum mopane woodland.

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Figure 2: A preliminary vegetation map displaying the 11 main habitat types found within Selati Game Reserve. Permission to use this map was given by Selati Game Reserve, 2018. There are two keys used for this map; one key is used for the colour pallet (bottom-left) and another key for the habitat names (top-right). From the map it can be concluded that the most dominant vegetation type within Selati Game Reserve is Colophosphorum mopane, Combretum apiculatum and Acacia spp mixed species woodland (Red/ Habitat 5). This map also displays the grid system that is used by the Selati staff to record sightings, manage water tanks and points of interests.

4.2. Data Collection Methods Random point sampling was chosen as the sampling method of this study. This was to enable an even spread of data points over nine of the eleven habitats of the reserve. The habitats based on figure two were coded as followed: - Combretum apiculatum woodland – Ca - Combretum apiculatum and Sclerocarya birrea mixed woodland – CaSb - Colophosphorum mopane and Combretum apiculatum woodland – CmCa - Colophosphorum mopane woodland – Cm

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- Colophosphorum mopane, Combretum apiculatum and Acacia spp mixed woodland – CCA - Terminilia sericia and Pogonarthria squarrosa woodland – TsPs - Riverine – Riv - Disturbed areas and natural drainage – DaNd - Disturbed areas and old fields - DaOf A random number of the grids as seen on Figure 2 is selected first. In the centre of this grid a GPS point is collected. This GPS point can then allow for a return to this location to conduct an elephant impact survey at a later date. The centre of the grid is also where the bird survey is completed, this will then allow for comparison of these areas within each grid between elephant damage, bird’s nests and the bird communities themselves. The bird survey is completed first and all bird surveys must be completed within two hours after sunrise due to this being peak time for bird activity. For the bird survey, the date, time and weather must be recorded as well as the grid number and habitat type. Count time lasts for five minutes with a one-minute period before the count time in order to allow birds to relax after being approached. The minute seen should be recorded, the species of bird, the number of individuals and whether they are heard, seen or flying (S/H/F). If a bird is seen then where the individuals are located are recorded using the codes; G for ground, T for trunk and C for canopy. Only birds seen or heard within the 25m2 quadrat are recorded. The nest type of each bird species is also recorded as seen in Beat About the Bush: Mammals and Bird (Carnaby, 2013), and the nest types are mentioned below. In order to compete the elephant impact surveys and nest surveys the 25m2 quadrat is measured out again in the same location as the earlier bird survey conducted earlier. All trees over a meter in height and all nests are counted within this area. The date, grid and habitat type all need to be recorded for both surveys. For the Elephant impact surveys, the tree species needs to be recorded as well as the trees dimensions, all in centre meters. The total height of each tree and the canopy height (the height to the first primary branch) is also recorded as well as the canopy spread or diameter which is measured from the furthest point of the canopy on one side of the tree to the furthest point of the other side of the canopy. If a tree does in fact have Elephant damage, then the type of damage is recorded using one of the codes as followed below which corresponds to a certain type of elephant damage:

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A - Pulled or kicked out B - Pushed over and dead or apparently dead C - Main trunk broken, is or appears dead D - Main trunk broken but re-sprouting or likely to re-sprout E - Pushed over but still alive F - Main trunk tusk slashed G - Main trunk debarked H - Roots exposed and eaten J - Primary branches broken K - Secondary and/or smaller branches broken For the nest surveys the nest dimensions, nest type, tree species, the location in the tree using the same codes as the bird survey for location, G/T/C, whether the nest is active or inactive, if the tree the nest is located in has any elephant damage and if so then the type of damage. If the nest is active, then the bird species using the nest needs to be recorded. If the nest is deemed active, then the potential species usage is recorded. In order to determine the type of nest the author followed the same categories as found in the book; Beat About the Bush: Mammals and Bird (Carnaby 2013). The types of nest categories used in the nest survey were as followed: scrape/depression, tight cup, open bowl, stick platform, enclosed woven structure – supported, enclosed woven structure – suspended, dome of grass or sticks, cavity, excavated tunnels, floating platform and mud pellet nest under overhang. In order to determine the species usage of a known nest, then the type of tree, location of the nest in the tree (Ground/ Canopy/ Trunk), the nests dimensions and the egg type and colour was recorded. The book Roberts Nests & Eggs of Southern African birds (Sinclair et al 2014) was used to determine the species usage based on the above mentioned data collection methods. Natural hole in wood and excavated hole in wood that are mentioned in the book; Beat About the Bush: Mammals and Birds (Carnaby 2013) were coupled together under the cavity nesting guild during this study.

4.3. Statistical Analysis Firstly, a chloropleth map will be created to display the elephant damage for selected plots throughout the reserve. The percentage of trees that are damaged will be calculated via: number of damaged trees/ number of trees x 100. The chloropleth map

14 is then generated on a map of the study site created by Selati Game Reserve themselves (Selati Game Reserve, 2018). The colours chosen to use for each damage value include: Green for low damage plots between 0-25%, yellow medium for damaged plots of a damage value between 26-50%, orange of high plots of damage between 51-75% and finally red for damage plots of greater than 76% upwards and including 100% damaged plots. Primer 6 will also be used in the statistical analysis of this study. Firstly, a Bray- Curtis similarity matrix will be completed for both the bird survey data on a species and guild level and the vegetation survey using Primer 6. After the Bray-Curtis similarity matrix is completed a two-way ANOVA will be generated comparing both habitat and elephant damage variables to the overall bird and tree community data, in order to determine which factor has a greater impact on determining the bird communities found within each habitat type. SIMPER tests will also be completed to compare the similarities between the bird and tree communities within each surveyed plot, as well as using a SIMPER test to calculate the similarities between both bird and tree communities based on each habitat type. A BEST analysis will also be used via Primer 6 in order to determine whether habitat variables has any impact on the bird communities and how elephants can possibly modify these variables. The four habitat variables include: tree height, canopy height, canopy spread and tree count. A mean would then need to be calculated for each of these four habitat variables per surveyed plot first however, before BEST program can be run. The RELATE tool will also be used to determine if bird community similarity is based on either habitat type or elephant damage. All graphs and charts produced in Primer 6 will be placed into the appendix. Figures will include a Species Sample Matrix for the habitat and damage variables for the bird community data and a habitat matrix for the tree community data, as well as a cladogram for both bird and tree communities. These findings will then allow for determination of similarity between surveyed plots based on multiple figures. The results for the damage factor matrix of similarity will be useful to determine if bird communities are similar in areas of similar elephant damage. The created ANOSIM figures will also be placed in the appendix. All these figures will be generated for the guild level also. It must be noted however that all work produced in Primer 6 will be used to identify factors affecting the bird communities and not the nesting potential of bird species.

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In terms of African Elephant impact on bird nest availability, the number of potential nesting trees will be generated from the elephant impact surveys. The number of possible nesting trees that are damaged by elephants will also be calculated. This will be calculated on both a species and guild level. Species used in the analysis will be based on paper based references of tree preference as well as field based data of known species that are known to currently use nesting sites within the confines of Selati Game Reserve, as well as species that are currently listed as vulnerable or higher based on the IUCN Red List as of August 2018. Species based tree usage of known nesting trees will be generated for stick platform, dome of grass and stick, tight cup, ground nesters and both small and large cavity nesters. Nest availability for large canopy nesters will be calculated based on field data collected as well as a report published by Henley & Henley (2005) based on tree selection in Southern Ground Hornbills (Bucorvus leadbeateri). With dome of grass and stick nesters, only hamerkop (Scopus umbretta) nesting trees (Liversidge 1963) will be analysed and for open bowl nesters, all methods mentioned below will be used to generate a combined number of available nesting trees for this guild. All of the species that will be looked at in greater detail will be raptors, which are open bowl nesters (Tarboton 2011). Firstly, tree preference for the Bateluer (Terathopius ecaudatu) will be calculated based on Herholdt et al (1996), Tarboton (2011), and any field data collected, for the Wahlberg’s Eagle (Hieraaetus wahlbergi) Tarboton (2011) and collected field data will be used and for the African Hawk-eagle (Aquila spilogaster), by Franklin (2018) and Tarboton (2011) as well as also field based data collected will be used. For the Tawny Eagle (Aquila rapax), Kendall et al (2017), Tarboton (2011), Herholdt et al (1996) and field data will be used and finally for the Martial Eagle (Polemaetus bellicosus) will be based on tree species and sizes from Herholdt & Kemp (1996), Tarboton (2011) as well as also using the authors field based data. Vulture nesting trees will also be calculated, however there have been no known vulture nests in Selati so only literature based tree estimates will be used. For the Lappet-faced Vulture (Torgos tracheliotos), Tarboton (2011), Kendall et al (2017) and Rushworth et al (2018) will be used to predict potential nesting trees, whilst for the White-backed Vulture (Gyps africanus), Kemp & Kemp (1975), Herholdt & Anderson (2006), Tarboton (2011), Monadiem et al (2016), Kendall et al (2017) and Rushworth et al (2018) will be used. In terms of the smaller vulture species, Monadiem et al (2016) and Tarboton (2011) will be used for Hooded Vulture (Necrosyrtes monachus)

16 potential tree usage for nesting and lastly for the White-headed Vulture (Trigonoceps occipitalis), Rushworth et al (2018) and Tarboton (2011) will be used. This will provide a detailed insight into how much potential nesting trees are damaged by elephants on a species level for these increasingly threatened raptors.

5.0. Results 2250 individual birds of 95 species were recorded over the five-week survey period as well as 42 tree species, with 151 bird plots surveyed and 74 elephant damage plots being surveyed respectively. 100% of all bird species recorded were resident species. The Cape Turtle Dove (Streptopelia capicola), Southern Yellow-billed Hornbill (Tockus leucomelas), and the Grey Go-away Bird (Corythaixoides concolor) were the most frequently occurring bird species, being encountered 170, 108 and 106 times respectively over the five-week survey period. In terms of nesting guilds, 41.06% of all birds identified within the bird survey were of the tight cup nesting guild, 24.80% were of the stick platform nesting guild and 22.83% of all birds recorded were of the cavity nesting guild. The remaining six nesting guild types recorded during the bird survey accounted for the other 11.31% of recorded birds. All surveyed elephant damage plots an equivalent bird survey completed within each plot however, due to time constraints not all bird survey plots have a corresponding elephant damage plot for comparison. These bird survey plots without a respective elephant damage plot were not used in any of the statistical analysis bar the primer plot comparison analysis. Whilst completing the elephant impact plots 3376 trees were surveyed and a total of 33 nests were found, with five of these nests being active. The majority of nests were located within knobthron, Senegalia nigrescens (33.33%), mopane, Colophospherum mopane (27.27%) and red bush willow, Combretum appiculatum (15.15%) trees respectively. Five nests were found within areas of low elephant damage, 6 nests were found in areas of medium damage, 21 nests were found in areas of high elephant damage and 2 nests were found in areas of very high elephant damage.

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Table 1: Table displaying the number of nests and the percentages of nests discovered per elephant damage category alongside the number of plots surveyed and the percentage number of the overall number of plots with that same type of elephant damage. Nests discovered include both active and inactive nests as well as potential nesting sites discovered. Elephant Impact Number of Plots Number of Nests Damage Category Surveyed Discovered Low Elephant 3 (4%) 5 (15%) Damage (G)

Medium Elephant 30 (41%) 6 (18%) Damage (Y) High Elephant 34 (46%) 21 (62%) Damage (O) Very High Elephant 7 (9%) 2 (5%) Damage (R) Totals: 74 34

All habitat types from figure 2 had at least two data points recorded for either survey type (table 2), excluding habitat type 7 and 9 based on figure 2 habitats. These habitats ere the Inselbergs and Sporobolus nitens Saline areas. The inselberg habitat (Habitat Type 7) was not considered as elephants cannot reach the majority of the kopjes located within these habitats and Sporobolus nitens saline areas (Habitat Type 9) were not used as they cover a substantially small area of the reserve compared to the other habitats, at less than 3km2. The most surveyed habitat was the CCA (Colophosphorum mopane, Combretum apiculatum and Acacia spp missed woodland), with 53 surveyed bird survey plots and 24 elephant impact survey plots.

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Table 2: Table 1 displays the number of bird and elephant surveys where data was collected in each of the ten chosen surveyed habitat types as well as the totals of both these survey types. The habitat types are coded in the same way as was shown in the data collection methods of the methodology section of this report. Habitat Type Survey Type Ca CaSb CmCa CCA Cm DaNd DaOf Riv TsPs Total Bird Survey 10 19 22 53 19 8 2 14 4 151 Elephant 8 10 11 24 6 5 2 6 2 74 Damage Survey

Figure 3: A chloropleth map displaying Selati Game Reserve and the percentages of elephant damage of the 74 grid squares surveyed. Grids that had 0-25% of trees recorded being damaged are displayed as green squares, medium damaged grids, of between 26 and 50% damage are displayed as yellow squares, whilst orange squares are grids that had high levels of damage, between 51-75%. Red squares are grids which had a very high percent of elephant damage between, 76-100% damage. The base map used for this chloropleth map was generated by Selati Game Reserve.

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Based on the results obtained from Primer 6, it can be determined that African elephants are not having a negative impact on the overall bird community on both a guild and species level as well as also having no impact on the ability for the bird communities to nest on again a species and guild level. From the SIMPER analysis (tables 3, 4, 5, 6) there were no patterns identified on both a species and guild level, apart from that on a species level only the same 7 species (Black-headed Oriole, Blue Waxbill, Cape Turtle Dove, Chinspot Batis, Fork-tailed Drongo, Grey Go-away Bird and Yellow-billed Hornbill), contributed greatly to the similarity and dissimilarity of the bird communities of the surveyed elephant damage plots. There was a similar pattern witnessed on a guild level also, where only four differing nesting guilds (tight cup, cavity, stick platform and scrape) contributed greatly to the similarity and dissimilarity of the bird communities of the surveyed elephant damage plots. However, there is no pattern between how these species and guilds make up the composition of the SIMPER results. On a guild level there is also no change in both the level of similarity and dissimilarity of canopy and ground nesting species over the increasing gradient of elephant damage, then again scrape or ground nesters on appear within the SIMPER analysis on both the opposites ends of the damage gradient. It can thus be concluded that the composition of birds on a species and guild level do not change over differing levels of elephant damage, which suggests that there should be no impact on the overall potential nesting ability of each species and guild within areas of differing elephant damage.

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Table 3: Table displaying the dissimilarity of bird abundances compared to each damage category type (G, O, Y R), with bird species chosen based on the top five species that contributed the most to the dissimilarity between the plots within each elephant damage type. These statistics are based on the data gathered from the SIMPER analysis via the use of Primer6. Elephant Impact Species Nesting Guild Percentage Damage Category Dissimilarity (%) Low Elephant Cape Turtle Dove Stick Platform 8.54 Damage (G) Chinspot Batis Tight Cup 7.58 Blue Waxbill Tight Cup 5.82 Fork-tailed Drongo Tight Cup 4.72 Yellow-billed Hornbill Cavity 2.16 Medium Elephant Cape Turtle Dove Stick Platform 8.09 Damage (Y) Fork-tailed Drongo Tight Cup 7.55 Yellow-billed Hornbill Cavity 4.53 Grey Go-away Bird Stick Platform 4.32 Chinspot Batis Tight Cup 4.19 High Elephant Cape Turtle Dove Stick Platform 10.97 Damage (O) Fork-tailed Drongo Tight Cup 6.75 Yellow-billed Hornbill Cavity 6.24 Blue Waxbill Tight Cup 5.60 Chinspot Batis Tight Cup 4.82 Very High Elephant Cape Turtle Dove Stick Platform 8.65 Damage (R) Fork-tailed Drongo Tight Cup 8.62 Chinspot Batis Tight Cup 6.99 Yellow-billed Hornbill Cavity 4.51 Blue Waxbill Tight Cup 4.03

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Table 4: Table displaying the similarity of bird abundances compared to each damage category type (G, O, Y R), with the bird species chosen based on the top five species that contributed the most to the similarity between the plots within each habitat type. These statistics are based on the data gathered from the SIMPER analysis via the use of Primer6. Elephant Impact Species Nesting Guild Percentage Damage Category Similarity (%) Low Elephant Black-headed Oriole Tight Cup 19.24 Damage (G) Chinspot Batis Tight Cup 18.89 Cape Turtle Dove Stick Platform 12.32 Yellow-billed Hornbill Cavity 10.77 Blue Waxbill Tight Cup 8.99 Medium Elephant Cape Turtle Dove Stick Platform 17.06 Damage (Y) Chinspot Batis Tight Cup 15.66 Fork-tailed Drongo Tight Cup 14.74 Grey go-away Bird Stick Platform 11.05 Yellow-billed Hornbill Cavity 10.66 High Elephant Fork-tailed Drongo Tight Cup 13.31 Damage (O) Cape Turtle Dove Stick Platform 13.81 Grey Go-away Bird Stick Platform 12.39 Black-headed Oriole Tight Cup 12.13 Chinspot Batis Tight Cup 11.43 Very High Elephant Chinspot Batis Tight Cup 30.52 Damage (R) Fork-tailed Drongo Tight Cup 23.44 Black-headed Oriole Tight Cup 9.96 Yellow-billed Hornbill Cavity 9.96 Cape Glossy Starling Cavity 9.96

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Table 5: Table displaying the dissimilarities of bird abundances within each habitat type on a guild level, with either five nesting guild types chosen based on the top three nesting guilds or any guilds that account for above 20% of the dissimilarity between the plots within each habitat type. These statistics are based on the data gathered from the SIMPER analysis via the use of Primer6. Elephant Impact Nesting Guild Type Percentage Damage Category Dissimilarity (%) Low Elephant Stick Platform 29.01 Damage (G) Tight Cup 21.60 Scrape 15.34 Medium Elephant Stick Platform 24.89 Damage (Y) Cavity 20.73 Tight Cup 18.76 High Elephant Stick Platform 28.47 Damage (O) Tight Cup 20.04 Cavity 19.69 Very High Elephant Stick Platform 31.83 Damage (R) Tight Cup 23.03 Scrape 15.40

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Table 6: Table displaying the similarity of nesting guilds compared to each damage category type (G, O, Y R), with either five nesting guild types chosen based on the top five nesting guild types or any guilds that account for above 20% of the similarity between the plots within each habitat type. These statistics are based on the data gathered from the SIMPER analysis via the use of Primer6. Elephant Impact Nesting Guild Type Percentage Damage Colour Similarity (%) Low Elephant Tight Cup 48.90 Damage (G) Cavity 27.08 Stick Platform 21.95 Medium Elephant Tight Cup 49.27 Damage (Y) Stick Platform 22.60 Cavity 22.41 High Elephant Tight Cup 43.17 Damage (O) Stick Platform 28.26 Cavity 24.38 Very High Elephant Tight Cup 57.56 Damage (R) Cavity 38.53

There were also data that was collected and interpreted from Primer6. Both the BEST (figure 4) and RELATE (figure 5 and 6) tools were used to determine whether there was any relationship between the four measured habitat variables (height, canopy height, canopy spread and tree count) and the bird communities on a species and guild level. Based on the BEST results (figure 4) it can be determined that on a species level, the four measured habitat variables do not have an impact on the composition of the bird communities, this can be supported by the p value (0.047) being right in the centre of the histogram and not in the outer 5% tail, leading to the suggestion that the results of the BEST are not significant. On a species level this is supported by the RELATE tool (figure 5), which was used to complete a similar function. Based on the RELATE tool on a species level, the four measured vegetation factors had no relationship with the bird communities, suggesting that both the above mentioned factors have no impact on the bird communities on a species level. On a guild level the same results can be seen, as the four measured habitat variables do

24 not show any evidence to support that they have any impact on the bird communities on a guild level (figure 6). In both instances, neither of the calculated the p value (0.018 and –0.036 respectively) lay within the outer 5% tail of the respective histograms. The BEST results are gathered from the data of the two respective Species Sample Matrix’s from both bird and tree plots (figures 12, 13 and 17), whereas the RELATE results are gathered from the individual Species Sample Matrix’s themselves againts another triangular Species Sample Matrix, which in the case of this investigation is based on the four mentioned vegetation factors along with the factors inputted into the Species Sample Matrix’s themselves. They are habitat type for figures 10 and 20 and elephant damage for figure 11 and 21, with figures 10 and 11 contributing to the RELATE figure 5 and figures 20 and 21 for RELATE figure 6.

Figure 4: BEST Primer6 graph based on Spearman’s rank coefficient using BIOENV method which compared the bird communities on a species level to the four measured habitat variables (height, canopy height, canopy spread and tree count). Test statistic was 0.047, which means BEST results are not significant.

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Figure 5: RELATE tool used in Primer6 to determine if there is a relationship between vegetation factors (height, canopy height, canopy spread and tree count) and bird community occurrence on a species level, using weighted Spearman’s rank coefficients. Test statistic was calculated to be 0.018. Significance of sample statistic 1.9%.

Figure 6: RELATE tool used in Primer6 to determine if there is a relationship between vegetation factors (height, canopy height, canopy spread and tree count) and bird nesting guild occurrence using weighted Spearman’s rank coefficients. Test statistic was calculated to be -0.036 Significance of sample statistic 1.7%.

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Based on data collected in the field and on literature research discussed in section 4.3, the overall number of potential nest were calculated for the whole reserve as well as the number of trees negatively damaged by elephants. Based on the results gained from these calculations, it can be seen that elephants are not having a very large impact on the potential for bird species to nest on a species level (table 7), with the highest being 33.33% of trees that can be potentially used by African Hawk-eagles have been negatively damaged by elephants at the study site. This is the largest percent of trees damaged by a substantial amount with the next largest on a species level being 18.75% of potential martial eagle nests being damaged by elephants. The potential nesting trees that were impacted on the lowest were the trees sued by hooded vultures (3.13%) and white-backed vultures (5.26%) respectively. On a conservation note, it is welcome to see that apart from lappet-faced vultures there is still the potential for these large and endangered raptors to breed within Selati Game Reserve, and with very little to no elephant impact contributing to the potential breeding of these species at this point in time. However, it should be considered that these values are highly down to chance due to the extremely high p values (0.99 and 1.00 respectively). On a guild level however, the impact elephants are having is larger (table 8) with all guilds having greater than 40.10% of all potential nesting trees being negatively damaged. The guild that is impacted by elephants the most at the study site was both the large canopy nesters and the stick platform guilds, which both had 56.63% of all potential nests damaged by elephants.

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Table 7: Table displaying the number of potential nesting trees calculated to be available for each species throughout the study site and the number of these trees negatively damaged by elephants. Standard deviation () was also calculated for each individual species as well as an overall chi-squared value of 4.05 which generated an overall p-value of 0.99. All species listed below are all classed as birds of prey/raptors which are all open bowl nesters. Species Number of Potential Number Nesting Trees Damaged Bateluer 64 9  3 Wahlberg’s Eagle 61 9  3 African Hawk-eagle 90 30  6 Tawny Eagle 61 9  3 Martial Eagle 16 3  2 Lappet-faced Vulture 0 0  0 White-backed Vulture 19 1  1 White-headed Vulture 61 9  3 Hooded Vulture 32 1  1

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Table 8: Table displaying the number of potential nesting trees calculated to be available for each nesting guild throughout the study site and the number of these trees negatively damaged by elephants. Standard deviation () was also calculated for each guild as well as an overall p value (1.00) based on chi squared test with an overall value of 6.34. It must be noted as not all guilds were chosen to be used, as guild such as excavated tunnel and mud pellet under overhang do not require trees for nesting. Nesting Guild Number of Potential Number Damaged Nesting Trees Scrape (Ground Nesters) 1474 604  24 Small Cavity Nesters 1105 599  24 Large Cavity Nesters 747 423  20 Dome of Grass and Sticks 345 180  13 Open Bowl 212 102  10 Stick Platform 747 432  20 Tight Cup 2003 1054  32

6.0. Discussion Based on the results of this investigation both the predicted hypotheses in terms of guild occurrence, were incorrect and in fact there was no change in the abundance of canopy nesters and ground nesters over a changing elephant damage gradient. There was also substantially lower percent of suitable nesting trees that were damaged than was predicted, thus meaning the third and final hypothesis of this study was incorrect. It can be concluded based on the findings of the results that African bush elephants are having little to no impact on the ability for birds to nest on both a species and a guild level within Selati Game Reserve (table 7 and 8). However, it must be noted that on a guild level elephants seem to be having a greater impact on the nesting potential (table 8). The p values however, for both table 7 and 8 are also very high, 0.99 and 1.00 respectively, suggesting that the results collected are heavily down to chance. The SIMPER results both on a species and guild level also show no change in species or guild composition over a changing elephant gradient. It is possible that feeding behaviour could explain these results as some species such as the fork-tailed drongo

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(Dicrurus adsimilis) and hornbill species (Tockus spp) will follow elephants and other large mammals (Thomson 1964). As the large mammals travel they disturb insects which these birds will then forage on (Thomson 1964) suggesting that these species will follow large mammals such as elephants and thus be located within plots of higher elephant damage. Also how common species are within the study site will also impact the SIMPER results, as common species will appear more often due to their higher encounter ratios (Stokke et al 2014). On the one hand these results do support the findings of other research (Herremans 1995; Reardon 2012, Rushworth et al 2018), while on the other hand the results seem to disregard the findings of other studies (Jenamiso et al 2015; Ogada et al 2008). This could be down to a number of factors, with one being the actual elephant densities within these study sites. For instance, Rushworth et al (2018) conducted multiple surveys on how elephant damage impacted upon vulture nesting in the Kwazulu-Natal region of South Africa. They concluded that even where elephant populations were above the 0.43 density that is determined sustainable (Ogada et al 2008), they had no impact on vulture nesting potential and that there was no difference between the impact elephants are having on vulture nesting in considerably high elephant densities and considerably low elephant densities. It should be noted that 66.7% of reserves used in this study had an elephant density above the recommended (Rushworth et al, 2018). For comparison to this, Selati Game Reserve has a calculated elephant density of 0.42 individuals per km2. Even though not considerably lower, the elephant density of Selati Game Reserve is below the recommended elephant density. Likewise, to the findings of Rushworth et al (2018), no vulture species that have the possibility of nesting at the study site still having 85% of any possible nesting trees remaining at the study site. Similarly, again with research conducted by Vogel et al (2014) only 9.6% of vulture nesting trees and 29.4% of raptor nesting trees had been damaged by elephants. These results obtained by Vogel et al (2014) are not too distinct from the results gathered for table 7 for this study. It has been observed by Rushworth et al (2018), Vogel et al (2014) and this study that elephants and raptors both utilise knobthorn trees (Senegalia nigrescens) for differing resources which in the future could become a possible conservation implication for preserving raptor species due to elephants reducing the suitability of these knobthorn trees for raptor nesting (Vogel et al 2014). Unfortunately, in the long term these nesting trees could become vulnerable to tree feeling by elephants (Rushworth et al 2018). This increases the

30 concern that possible suitable nesting trees for endangered raptors could disappear (Kendall et al 2017) in the distant future. Tree selection by lappet-faced vultures also have a similar preference by elephants (Rushworth et al 2018), thus suggesting that lappet-faced vultures could be under extreme pressure from elephant damage. A very limited number of lappet-faced vulture nests have been discovered in areas that elephants also occupy, with zero being found at Selati Game Reserve and two in the study conducted by Rushworth et al (2018) throughout the whole Kwazulu-Natal region. In other parts of southern Africa, this is not the case as elephants have been shown to negatively impact the bird communities around them (Jenamiso et al 2015; Ogada et al 2008). Along the Chobe Riverfront, the lowest recorded elephant density was 3.34 elephant per km2 and the highest was 20.97 elephants per km2 (Jenamiso et al 2015). In this study along the Chobe riverfront there was a negative correlation between elephant density and bird abundance, which is unlike the results collected at Selati Game Reserve. It was also exposed that in the Masai Mara at high elephant densities the number of trees that were deemed suitable for raptor nesting were significantly reduced (Kendall et al 2017), however, there were still between 2-6million suitable nesting trees present in the Masai Mara for raptors. As well as bull elephants felling more trees (Cook et al 2018, Midgley et al 2005, Henley & Henley 2005), bull elephants have also been known to target taller trees for felling (Henley & Henley 2005), possibly as a show of strength or to allow for a greater foraging potential from these taller trees. This can suggest that elephant populations with a greater number of bulls will experience more tree feeling (Henley & Henley 2005) and greater altering of the vegetation (Henley & Henley 2005). This could imply that elephant populations with a high density of bulls should be controlled if bird nesting is a priority. It is also a concern if these bull elephants are felling taller trees as these taller trees are in short supply and the only trees that can be used by increasingly threatened species such as ground hornbills (Henley & Henley 2005) and raptors (Vogel et al 2014; Kendal et al 2016; Rushworth et al 2018). As well as bird nesting potential in terms of overall bird communities there was no significant difference between bird communities in areas of differing elephant damage on both a guild and species level at Selati Game Reserve. This is further supported by the results of the species sample matrixes (figures 11 and 21) which shows no difference in bird communities in areas of differing elephant damage on both a guild and species level.

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It has been suggested that possibly high elephant densities are not the determining factor in bird abundances (Jenamiso et al 2005) and thus bird nesting potential. It has been suggested that habitat type is the lead contributor to avian diversity (Jenamiso et al 2015). This is due to some species preferring particular habitats as they are adapted to those microhabitats for foraging and breeding (Jenamiso et al 2015). It must be stated however, that elephants can modify these habitats. For example, elephants can modify large expanses of dense thickets to open thickets (Kerley & Landman 2006) which thus have changed the community of birds that are found within tropical thickets of South Africa (Kerley & Landman 2006). The open elephant modified thickets had more granivores and insectivores whereas the non-modified intact thickets had more frugivorous species (Kerley & Landman 2006). This however, does suggest that elephants can in-fact impact the bird communities around them. However, even though elephants can damage and alter the vegetation around them (Shannon et al 2011; Jenamiso et al 2015; Mograbi et al 2017; Reardon 2012; Williams 2017), the impact this change in the vegetation is having on bird communities is non-existent in Selati Game Reserve based on the BEST analysis (figure 4). This alludes to the fact that the structure of the vegetation is not the factor that determines bird abundance and diversity. However, elephant impact on Acacia spp in Waza National Park in Cameroon, seemed to impact trees from the mature age class, with 74% of mature Acacia trees being seriously damaged by elephants (Tchamba 2008). This could be detrimental to bird nesting as the majority of bird guilds use large mature Acacia species for nesting (Liversidge 1963; Vogel et al 2014; Kendal et al 2016; Rushworth et al 2018). Nonetheless, it can be assumed from the results of this study that even with a change in vegetation structure that can be caused by elephants, bird communities will not be affected both on a guild and species level, and conversely the ability of these bird species to nest should not be affected. It has been considered that elephants have contributed to the decline of forest cover across Africa over the last 30 years (Kendall et al 2017) thus leading to large scale habitat change and alteration (Kendall et al 2017). Like most studies there are some limitations too this study, one limitation is that the data collection for this study only lasted five weeks during the dry season. This resulted in all summer migrants being missed during the data collection. Crepuscular and nocturnal species were also not counted during this survey. Species that were counted within the data collection period should be compared based on the

32 assumption that all species have an equivalent encounter and detection ratios (Stokke et al 2014). Unfortunately, this is not the case (Stokke et al 2014), mainly due to reason such as behaviour, size and colouration (Stokke et al 2014) which could lead to overestimation of some species and underestimation of others (Stokke et al 2014). The habitat itself can also cause some problems for bird identification and recording, as habitats that have less dense vegetation would allow for birds to be seen more easily than habitats with dense, thick vegetation (Stokke et al 2014). However, the methods used should overcome this due to birds also being recorded based on vocalisations as well as any visual sightings and the time of day chosen for data recording occurred in optimum bird activity. Night time bird surveys would also need to be completed to account for any nocturnal species that the day time bird survey would omit. Bird abundance and richness has also been discovered to have decreased in dry seasons (Ogada et al 2008), which could lead to an overestimation of elephant impact for this study as there is likely to have been less species within Selati Game Reserve at time of data collection. Seasonally there are also changes in both structure and food abundances for both elephants and birds (Jenamiso et al 2015), which could impact where individuals are, which would then mean a more thorough study of the reserve would need to be completed. Selati Game Reserve has seen drought condition over the last four years, which has seen a drastic reduction in vegetation cover. As rainfall is vital for tree growth and regeneration (Moe et al 2017) a lack of rainfall could lead to fewer trees being counted when the data was collected, possibly leading to fewer than average trees being counted. This could impact the results of the elephant damage plots, possibly resulting in an over calculation of elephant damage. Another limitation is that only 74 plots were surveyed for elephant damage and 151 plots were used for bird surveys. This is a relatively small number of plots for the size of the study site which could possibly result in the reserve having a greater number of heavily damaged plots than expected based on the data collected for this study. Elephant behaviour itself can also change with time, thus proving to be another limitation of a short data collection period. For instance, due to elephants being able to change their diet on a seasonal basis (Codron et al 2006; Kos et al 2012; Reardon 2012; Shannon et al 2011), it would be assumed that there would be more elephant damage in the drier winter months. This would be due to the lack of grass available to elephants in the dry season thus forcing them to browse more often (Shannon et al 2011; Kos et al 2012, Reardon 2012, Stokke & du Toit 2000). Therefore, a longer

33 study could allow for elephant damage to be measured over a longer period to see if there is a change in damage through different seasons and whether this change impacts on bird communities and the ability of these bird communities to nest. As bull elephants also fell more trees (Cook et al 2018, Midgley et al 2005, Henley & Henley 2005), a comparison of bull and female densities could be compared to one another in order to determine the area of extent of both sexes within the reserve and whether there is a change in the elephant damage within these areas. This could consequently be impacting on the bird communities in differing ways so this would also be tested againts the impact of both elephant sexes. Elephant distribution itself also varies on a seasonal basis (Williams et al 2017). It was discovered by Williams et al (2017) that elephant distribution varies with temperature and precipitation as well as the presence of waterholes. Based on the chloropleth map (figure 3) generated, this does not seem to be the case in Selati, as there are a greater number of very high damaged plots at greater distances from the main water source of the reserve. However, the presence of both man mad and natural water sources could explain this distribution of elephant damage throughout the study site as elephants will not have to congregate around the Selati River. Within these riverine habitats along the Selati River some of the tallest trees were recorded. The movement of elephants away from the river could benefit bird nesting as these larger trees have a reduced chance of being felled with a reduction in contact time with elephants. This is supported by the fact that overall the riverine habitat had the lowest average percentage damage (46%), compared to the other habitats. For comparison, the habitat with the highest average percent damage was disturbed areas and old fields with 82%. Control plots on the other hand had an average damage percentage of only 3%. These temporal movements of elephants thus displays the importance of studying elephant movement and behaviour temporally (Williams et al 2017), thus suggesting a longer sampling method than what was used by the author for this study. Vegetation is not an influential factor in elephant distributing (Williams et al 2017), meaning this could be beneficial to bird nesting as areas of dense vegetation could allow for a greater number of nesting trees to still remain standing, but contradictory to this, the mesic savannah habitats of Selati Game Reserve allow for vegetation, and thus food sources for elephants, to grow throughout the reserve meaning elephants will not have to travel great distances for food (Williams et al 2017) and thus prevent other feeding sites from regenerating (Williams et al 2017). The majority of game reserves within southern Africa are also fenced, thus also

34 preventing the natural movements of elephants (Rushworth et al, 2018). This itself will also prevent vegetation from regenerating and allowing trees to grow to heights needed especially by larger raptors (Reardon 2012; Vogel et al 2014; Kendall et al 2017; Rushworth et al 2018) and cavity nesters (Henley & Henley 2005). It has also been proven that free ranging elephants do not impact on bird communities (Williams et al 2017) due to their ability to move freely between different areas in search for food (Williams et al 2017) and to follow fresh growth (Williams et al 2017). However, free ranging elephants are more likely to come into contact with poachers and farmers which will possible lead to persecution of these elephants. It has been suggested that setting up small elephant free zones similar to the control plots used at Selati Game Reserve could serve as bird refuges (Ogada et al 2008), and that these areas could be as small as four hectares in size (Ogada et al 2008). If there was more than one plot being used these areas could be used on a rotational basis, allowing for regeneration and tree growth of other plots after elephants have utilised them. This would then allow for trees to grow to suitable heights that are used by larger bird species for nesting. If plots are used on a rotational basis, after large mammal disturbance by grazers such as elephants, this can facilitate tree regeneration (Moe et al 2017), due a reduction of competition with grasses (Moe et al 2017). More than 40% of bird species within the Great Limpopo Transfrontier Park (Kruger National Park) and thus Selati Game Reserve require tall trees (>5m tall) at one stage during their reproductive lifecycle (Reardon 2012). It has also been noted that due to elephant tree feeling, mortality of tree species >5m is higher than recruitment (Shannon et al 2011). Tree felling can also be a detriment to some tree species but not too others (Midgley et al 2005). Some species such as mopane can regenerate and regrow after being felled by elephants (Midgley et al 2005). This can result in no trees lost for bird nesting, apart from larger mopane trees that only large heavy birds can use. However, during this study no large raptor or cavity nests were found at the study site within mopane trees, only small cavity nests. This suggests that regeneration of mopane trees could support bird nesting once the tree is thick enough to prevent predation. Selati Game Reserve has many mopane trees, with 26% of all surveyed trees being mopane through all nine surveyed habitats and the fact that mopane trees can regenerate implies that these areas do not require any conservation intervention (Midgley et al 2005) and can thus remain felled and still require nesting habitat for birds, especially tight cup and ground/scrape nesters.

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Elephant free zones could be beneficial for increasing bird diversity and abundance (Ogada et al 2008), however if elephants were to be removed from specific areas, then these areas could possibly experience megaherbivore release (Kerley & Landman 2006) where species, both and animal and plant could develop independently in the absence of elephants and other megaherbivores (Kerley & Landman 2006). It should be considered that this process would take many years to begin to take effect. Megaherbivore release is also not likely to occur if plots are rotated on a yearly basis. Elephants also play a role in over 70% of ecological processes of savannahs and ticket habitats (Boshoff et al 2002; Kerley & Landman 2006) thus suggesting a functional difference in habitats that have and do not have elephants. In areas that have an absence of elephants, small plants are outcompeted by faster growing woody trees (Boshoff et al 2002). This can be beneficial to large canopy nesters that require tall trees (Reardon 2012; Vogel et al 2014; Kendall et al 2017; Rushworth et al, 2018) but can reduce undergrowth for small birds to use as protection or for nesting themselves (Boshoff et al 2002). Elephants are also reliable seed dispersers (Kerley & Landman 2006; Reardon 2012), with some trees such as Acacia species having up to 75% germination success from seeds contained within elephant dung (Reardon 2012), compared to a 12% germination success to those seeds that germinate via fruiting pods alone (Reardon 2012). As mentioned previously this can be beneficial to many bird species that require Acacia species such as knobthorn trees (Liversidge 1963; Vogel et al 2014; Kendal et al 2016; Rushworth et al 2018) for nesting. This is where elephant free plots may perhaps be useful, allowing these small seedlings to grow and develop after germination to a height that can be useful to all bird species for nesting. It must be noted that this may require many years to allow trees to grow to a size that elephants cannot fell. Another method discussed to control elephant number was through culls (Boshoff et al 2002; Freeman et al 2008). This is a very controversial method of control (Boshoff et al 2002; Freeman et al 2008), and so far, there has been no positive effects on biodiversity and tree growth after elephant culls (Boshoff et al 2002). Even though elephants are still considered vulnerable to extinction (Blanc 2008), within Southern Africa elephant populations are on the increase (Gadd 2003; Blanc 2008; Reardon 2012). This is mainly due to the success of elephant conservationists, however, when conservation of elephants becomes too successful and densities of elephants become too high, this could be of detriment of other species

36 of similar importance to savannah ecosystems such as birds (Gadd 2003; Roemer & Wayne 2003; Ogada et al 2008). Elephant conservation however is still important due to the decreasing numbers of elephants in other parts of their range (Blanc 2008), nonetheless, this should not detract from the conservation of birds, especially with the heavy decrease seen in many bird species across much of Sub-Saharan Africa (Henley & Henley 2005; Thiollay 2006; Huntley & Barnard 2012; Vogel et al 2014; Buechley & Sekerioglu 2016; Kendal et al 2016; Rushworth et al 2018). One species should not be compensated for the conservation of another (Roemer & Wayne 2003). It is a balancing act, even though possible, is difficult to control.

7.0. Closing Remarks To conclude based on the results of this investigation both of the predicted hypotheses in terms of guild occurrence, were incorrect and in fact there was no change in the abundance of canopy nesters and ground nesters over a changing elephant damage gradient and that there were no obvious negative impact elephants were having on bird nesting potential at the study site. Even though this study has limitations in terms of length of the study, the detail and amount of data collected overcomes this and allows room for future studies to be conducted at other periods of the year for comparison.

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8.0. References Blanc, J. (2008). Loxodonta africana (African Elephant). [ONLINE]. Available at: https://www.iucnredlist.org/species/12392/3339343. [Accessed 21st of January, 2019)

Boshoff, AF. Kerley, GIH. Cowling, RM & Wilson, SL. (2002). The potential distributions, and estimated spatial requirements, and population size, of the medium - to large-sized mammals in the planning domain of the Greater Addo National Park Project. Koedoe. 45. 85–116.

Boundja, R. P. and J. J. Midgley. (2010). Patterns of elephant impact on woody plants in the Hluhluwe-Imfolozi park, Kwazulu-Natal, South Africa. African Journal of Ecology. 48. 206-214.

Buechley ER & Sekerioglu, CH. (2016). The avian scavenger crisis: Looming extinctions, trophic cascades and loss of critical ecosystem functions. Biological Conservation. 198. 220-228.

Carnaby, T. (2013). Beat About the Bush: Mammals and Birds. 2nd ed. Cape Town, South Africa: Jacana Media.

Codron, J. Lee-Thorp, J. Sponheimer, M. Codron, D. Grant, RC. de Ruiter, DJ. (2006). Elephant (Loxodonta africana) diets in Kruger National Park, South Africa: Spatial and landscape differences. Journal of Mammalogy. 87 (1). 27-34.

Cook, RM and Henley, MD. (2019). Complexities associated with elephant impact on Sclerocarya birrea subsp. caffra in the Great Kruger National Park. South African Journal of Boatny. 121 (3). 543-548.

Cook, RM. Parrini, F. King, LE. Witkowski, ETF. Henley, MD. (2018). African honeybees as a mitigation method for elephant impact on trees. Biological Conservation. 217. 329-336.

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Cook, RM. Witkowski, ETF. Helm, CV. Henley, MD. Parrini, F. (2017). Recent exposure to African elephants after a century of exclusion: rapid accumulation of marula tree impact and mortality, and poor regeneration. Ecology Managing. 401. 107–116.

Cumming, DH. Fenton, MB. Rautenbach, IL. Taylor, RD. Cumming, GS. Cumming, MS. Dunlop, JM. Ford, AG. Hovorka, MD. Johnston, DS. Kalcounis, M. Mahlangu, Z. Portfors, CVR. (1997). Elephants woodlands and biodiversity in southern Africa. South African Journal of Science. 93. 231–236.

Derham, K. Henley, MD. Schulte, B. (2016). Wire netting reduces African Elephant (Loxodonta africana) impact to selected trees in South Africa. Koedoe - African Protected Area Conservation and Science. 58 (1). 231-237.

Franklin, B. (2018). Observations, considerations and nesting behavior of the African Hawk Eagle. [ONLINE]. Available at: http://safalconry.org/2016/05/20/observations- considerations-and-nesting-behavior-of-the-african-hawk-eagle/?i=2. [Accessed 28st of September, 2018].

Freeman, E. Whyte, I. Brown, JL. (2008). Reproductive evaluation of elephants culled in Kruger National Park, South Africa between 1975 and 1995. African Journal of Ecology. 42 (2). 192-201.

Fry, CH. Fry, K. (2010). Kingfishers, Bee-eaters and Rollers. 1st edition. Russel Friedman Books: South Africa.

Gadd, ME. (2002). The impact of elephants on the marula tree Sclerocarya birrea. African Journal of Ecology. 40. 940. 328-336.

Gadd, ME. (2003). Elephant ecology and conservation in African range-lands. PhD thesis. University of California, Davis.

Google Earth. (2018). Google Earth – Google Earth. [Online]. Available at: https://earth.google.com. [Accessed 15 Oct. 2018].

39

Henley, MD & Henley SR. (2005). Southern Ground Hornbill (Bucorvus leadbeateri). A population and habitat viability assessment workshop. Conservation Breeding Specalist Group. 1st ed, Apple Valley, Minnesota.

Herholdt, JJ & Anderson, MD. (2006). Observations on the population and breeding status of the African white-backed vulture, the black-chested snake eagle, and the secretarybird in the Kgalagadi Transfrontier Park. Ostrich. 77. 127–135.

Herholdt, JJ. Kemp, AC. Du Plessis, D. (1996). Aspects of the breeding status and ecology of the Bateleur and Tawny Eagle in the Kalahari Gemsbok National Park, South Africa. Journal of African Ornithology. 67 (4). 126-137.

Herholdt, JJ & Kemp, AC. (1997). Breeding status and ecology of the martial eagle in the Kalahari Gemsbok National Park, South Africa. Ostrich. 68 (4). 80-85.

Herremans, M. (1995). Effects of woodland modification by African Elephants Loxodonta africana on bird diversity in Northern Botswana. Ecography. 18 (4). 440- 454.

Holdo, RM. (2003). Woody plant damage by African elephants in relation to leaf nutrients in Western Zimbabwe. Journal of Tropical Ecology. 19 (2). 189–196.

Jenamiso, M. Rutina, L. Marokane, W. (2015). Avian Diversity in an Elephant Impacted Woodland along the Chobe Riverfront. Maun: Avian Ecology in Northern Botswana.

Kemp, AC & Kemp, MI. (1975). Observations on the White-backed Vulture Gyps africanus in the Kruger National Park, with notes on other avian scavengers. Koedoe. 18 (1). 51–68.

Kendall, C. Rubenstein, DI. Slater, Pl. Mondajem, A. (2017). An assessment of Tree Availability as a Possible Cause of Population Declines in Scavenging Raptors. Journal of Avian Biology. 49 (1).

40

Kerley, GIH. Landman, M. 2006. The impacts of elephants on biodiversity in the Eastern Cape Subtropical Thickets. South African Journal of Science. 102 (9). 395- 402.

Kos, M. Hoetmer, AJ. Pretorius, Y. De Boer, WF. De Knegt, H. Grant, CC. Van Langevelde, F. (2012). Seasonal diet changes in elephant and impala in mopane woodland. European Journal of Wildlife Research. 58. 279–287.

Liversidge, R. (1963). The nesting of the Hamerkop (Scopus umbretta). Ostrich. 34 (2). 55-62.

Midgley, JJ. Balfour, D. Kerley, GIH. (2005). Why do elephants damage savanna trees? African Journal of Science. 101 (5). 213–215.

Moe, SR. Eldegard, K. Rannestad, OT. Okullo, P. Lindtjørn, O. Støen, OG. Dale, S. (2017). Strong positive effects of termites on savanna bird abundance and diversity are amplified by large herbivore exclusion. Ecology and Evolution. 7 (23). 10079- 10088.

Mograbi, PJ. Asner, GP. Witkowski, ETF. Erasmus, BF. Wessels, KJ. Mathiew, R. Vaughn, NR. (2017). Humans and elephants as treefall drivers in African Savannas. Ecography. 40. 1274-1284.

Monadjem, A & Garcelon, DK. (2005). Nesting distribution of vultures in relation to land use in Swaziland. Biodiversity and Conservation. 14. 2079–2093.

Monadjem, A. Wolter, K. Neser, W. Bildstein, K. (2016). Hooded Vulture Necrosyrtes monachus and African White-backed Vulture Gyps africanus at the Oilfants River Private Nature Reserve, Limpopo Province, South Africa. Ostrich. 87 (2). 113-117.

Ogada, D. Gadd, M. Ostfeld, R. (2008). Impacts of large herbivorous mammals on the bird diversity and abundance in an African savanna. Oceologia, Issue 156 (2). 387-397.

41

Reardon, M. (2012). Shaping Kruger. 1st ed. Cape Town: Struik Nature. 12-29.

Roemer, G. & Wayne, R. (2003). Conservation in conflict: the tale of two endangered species. Conserv Biol. 17. 1251–1260.

Rushworth, I. Druce, DJ. Craigie, J. Coverdale, B. (2018). Vulnerability of vulture populations to elephant impacts in KwaZulu-Natal. Bothalia – African Biodiversity and Conservation. 48 (2).

Sande, E. C, Dranzoa. P, Wegge & J, Carroll. 2001. Nest survival of the Nahan’s Francolin Francolinus nahani in Budongo Forest Reserve, Uganda. 97–102. In Galliformes 2000: Proceedings of the 2nd International Galliformes Symposium, Kathmandu and Royal Chitwan National Park, Nepal, 24 September – 1 October, 2000.

Sekercioglu, CH. (2006). Increasing awareness of avian ecological function. Trends in Ecology and Evolution. 21 (8). 461-471.

Selati Game Reserve. (2018). Selati Game Reserve Home. [Online]. Available at: http://selatigamereserve.co.za. Accessed 27/09/2018.

Seloana, MQ. Kruger, WJ. Potgieter, MJ. Jordaan, JJ. (2017). Elephant damage to Sclerocarya birrea on different landscapes. International Journal of Biodiversity and Conservation. 9. 97-106.

Shannon, G. Thaker, M. Vanak, AT, Page, BR. Grant, R. Slotow, R. (2011). Relative Impacts of Elephant and Fire on Large Trees in a Savanna Ecosystem. Ecosystems. 14 (8). 1372-1381.

Sinclair, I. Hockey, P. Tarboton, W. Ryan P. (2014). The Illustrated Guide to Birds of Southern Africa. 3rd ed. Cape Town: Sruik Nature.

42

Skwono, AL. Bond, WJ. (2003). Bird community composition in an actively managed savannah reserve, importance of vegetation structure and vegetation composition. Biodiversity and Conservation. 12 (11). 2279-2294.

Stokke, S & du Toit, J. (2000). Sex and size related differences in the dry season feeding patterns of elephants in Chobe National Park, Botswana. Ecography. 23. 70- 80.

Tarboton, W. (2011). Roberts Nests & Eggs of southern African birds. 1st ed. Cape Town: Jacana Media.

Tchamba, MN. (2008). The impact of elephant browsing on the vegetation of Waza National Park, Cameroon. African Journal of Ecology. 33 (3). 184-193.

Thiollay, JM. (2006). Large bird declines with increasing human pressure in savanna woodlands (Burkina Faso). Biodiversity and Conservation. 15 (7). 2085-2108.

Thompson, AL. (1964). Birds associated with Elephants and Hippopotamuses. The Auk. 81 (3). 436-437.

Vogel, S. Henley, DH. Sieglinde, CR. Daniel, van de V. Carstens, C. Simmons, G. de Boer, WF. (2014). Elephant (Loxodonta africana) impact on trees used by nesting vultures and raptors in South Africa. African Journal of Ecology. 52 (4). 458-465.

Williams, H. Bartholomew, D. Amakobe, B. Githiru, M. (2017). Environmental factors affecting the distribution of African elephants in the Kasigau wildlife corridor, SE Kenya. African Journal of Ecology.

Wolf, S. Bothma, J. Du, P. Viljoen, PJ. (2002). Gamebirds: general management. Game Ranch Management. Van Schaik, Pretoria. 226-241.

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9.0. Appendices

Figure 7: Bird Cladogram showing similarities of the bird communities between all measured bird plots on a species level.

Figure 8: Bird Cladogram showing similarities of the bird communities between all measured bird plots on a species level, grouping plots based on their similarities when comparing plots based on the habitat factor. Red lines are one group of plots and the black line is another group, containing one plot, F16.

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Figure 9: Bird Cladogram showing similarities of the bird communities between all measured bird plots that had a corresponding elephant impact damage value, on a species level. Red lines are one group of plots and the black lines are another group of plots.

Figure 10: Species sample matrix bird plots based on habitat showing similarities of bird communities on a species level. Rings based on 40% similarity.

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Figure 11: Species sample matrix bird plots based on elephant damage showing similarities of bird communities on a species level. Rings based on 40% similarity. Not all bird plots present in figure 10 are shown as these are only plots that have a corresponding elephant damage value and category score (G, Y, O, R).

Figure 12: Bird ANOSIM graph based on R value frequency for damage colour (G, Y, O, R) across all habitat groups on a species level. Sample statistic is -0.032 and the significance level is 71%. This suggests these results are not significant due to statistic not lying in outer 5% of graph, thus suggesting that elephant damage has no impact on the bird communities on a species level.

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Figure 13: Bird ANOSIM graph based on R value frequency for habitat type across all habitat groups on a species level. Sample statistic is 0.277 and the significance level is 1.6%. The results are not significant due to statistic not lying in outer 5% of graph, thus suggesting that habitat type has no impact on the bird communities on a species level.

Figure 14: Tree Cladogram showing similarities between tree species communities within each plot.

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Figure 15: Species sample matrix tree plots based on habitat type showing similarity between tree species within each plot. Rings based on 40% and 60% similarity of plots, suggesting a very uniform pattern in tree coverage across the study site.

Figure 16: Tree ANOSIM graph based on R value frequency for habitat type across all habitat groups on a species level. Sample statistic is 0.532 and the significance level is 0.10%. The results are significant due to statistic lying in outer 5% of graph, thus suggesting that tree species is based on habitat type.

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Figure 17: Tree ANOSIM graph based on R value frequency for damage colour (G, Y, O, R) variable, across all habitat types on a species level. Sample statistic is 0.036 and the significance level is 34.4%. The results are not significant due to statistic not lying in outer 5% of graph, thus suggesting that elephant damage has no impact on the tree communities on a species level.

Figure 18: Bird Cladogram showing similarities of the bird communities between all measured bird plots that contained a corresponding elephant impact value on a guild level.

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Figure 19: Bird Cladogram showing similarities of the bird communities between all measured bird plots on a guild level, grouping plots based on their similarities when comparing plots based on elephant damage percentage per plot. Red lines are one group of plots and the black lines are another group of plots.

Figure 20: Species sample matrix bird plots based on habitat type showing similarities of bird communities on a guild level. Rings based on 40% similarity, displaying that on a guild level the bird communities of Selati Game Reserve are similar across all habitats and plots. Not all bird plots are shown as these are only plots that have a corresponding elephant damage value and category.

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Figure 21: Species sample matrix bird plots based on elephant damage showing similarities of bird communities based on guild level. Rings based on 40% similarity. Not all bird plots are shown as these are only plots that have a corresponding elephant damage value and category.

Figure 22: Bird ANOSIM graph based on R value frequency for habitat type across all elephant damage groups on a guild level. Sample statistic is 0.043 and the significance level is 2%. The results are not significant due to statistic not lying in outer 5% of graph, thus suggesting that habitat type has no impact on the bird communities on a guild level.

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Figure 23: Bird ANOSIM graph based on R value frequency for damage colour (G, Y, O, R) across all habitat groups on a guild level. Sample statistic is 0.001 and the significance level is 12%. The results are not significant due to statistic not lying in outer 5% of graph, thus suggesting that elephant damage has no impact on the bird communities on a guild level.

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