Chapter 5 HOME RANGE AND MOVEMENT OF INDIVIDUAL MELITHREPTUS WITH A FOCUS ON SHORT TIME SCALES 5.1 Introduction Movements of individual birds have received little attention in the ornithological literature. This lack of information on the movements of individual birds is even more surprising when considered against the backdrop of declining bird populations across Australia, and in particular the declining woodland birds of south eastern Australia. The use of current landscapes by birds is being inferred almost solely through survey techniques (e.g. Saunders 1989; Lynch and Saunders 1991; Saunders and de Rebeira 1991; Bentley and Catterall 1997; Mac Nally and Watson 1997; Wilson and Recher 2001; Fischer and Lindenmayer 2002; Mac Nally and Horrocks 2002; Olsen et al. 2003; Westphal et al. 2003). This is particularly true of nectarivore populations whose movements are often inferred from changes in abundance, usually in relation to nectar availability (e.g. Paton 1979; Collins and Briffa 1982; Collins et al. 1984; Collins 1985; Ford and Paton 1985; Paton 1985; Collins and Newland 1986; McFarland 1986c; Pyke and Recher 1988; Pyke et al. 1993; Mac Nally 1995; McGoldrick and Mac Nally 1998; Paton et al. 1999; Mac Nally and Horrocks 2000; Paton et al. 2004b). Work based on changes in abundance usually results in the movements of honeyeaters described in terms of ‘resident’ or ‘nomad’ (e.g. Keast 1968b; Carpenter and Reid 1988; Simpson and Day 1999; Higgins et al. 2001), rather than quantitative measures of home range or life-time range. Further annotation, such as ‘local nomad’ is often included. However, this gives very little detail about the actual scale over which individuals move, information that is essential to the effective management of populations. While most survey work has provided important insights into population movement, inferring use of landscape by populations from detailed knowledge of individuals is likely to provide a different perspective. One way in which the movements of individual honeyeaters have been investigated is in relation to territory size. Territory has been described as, ‘aggressive behaviour that occurs repeatedly in about the same location with associated submissive behaviour on the part of the individuals or groups to which the aggression is directed (Pyke et al. 1996)‘. The territory concept has been applied mostly to Phylidonyris novaehollandiae 120 in Australia (Paton 1979; Paton and Ford 1983; Paton 1985; McFarland 1986b; Paton 1986a; McFarland 1996; 2002), but few estimates of territory size are available. McFarland (1986b) found feeding territory size of pairs of P. novaehollandiae to be about 528 m2 (0.0528 ha) and single birds to be about 375 m2 (0.0375 ha). Birds also defended breeding territories, although no estimate of size is available (McFarland 2002). Radio-tracking as a method of determining honeyeater movement was first published in 1987 using radio-tags weighing about 1.5 grams and lasting up to 20 days (O'Connor and Pyke 1987). Since that time only a few studies have examined the movements of honeyeaters using radio-tags (Table 5.1). Of the studies using radiotelemetry techniques on honeyeaters, none have reported on the day to day movements of radio-tagged individuals or the overall home range of the species being investigated. The original study included both P. novaehollandiae and Phylidonyris nigra (White-cheeked Honeyeater) and defined a ‘grid’ home range only. ‘Current resident’ P. novaehollandiae spent 7% and P. nigra 23% of their time off the grid, but this time was not included in ‘grid’ home range estimates (Pyke and O'Connor 1993), presumably greatly underestimating the actual home range area. Movements of translocated Manorina melanocephala (Noisy Miner) were monitored using radio-tags primarily to assess the effects of translocation (Clarke and Schedvin 1997) and unpaired Lichenostomus melanops cassidix (Helmeted Honeyeater) were radio-tagged to determine the nature of their movements, with a particular focus on dispersal (Runciman et al. 1995). In both these cases, the only movement data published was maximum distance from the release site. There have been a few studies which examined home range size in honeyeaters (Table 5.2). The home ranges determined by these studies have all been less than 1 ha, suggesting very limited movement. Also, such a small home range suggests that the effect of fragmentation per se on honeyeaters is unlikely to be great. Roshier and Reid (2003) define a number of useful terms in describing the movements of individuals and species. Geographic range is the total area over which the species occurs and is reasonably well documented for most Australian birds (e.g. Blakers et al. 1984; Barrett et al. 2003). Life-time range is also a fairly straightforward concept, being the total area over which an individual moves during its lifetime. However, this is 121 poorly known for most species of bush birds, including honeyeaters, with the best, but still very limited, information coming from banding records. Finally, the home range of an individual is defined as, ‘that area traversed by the individual in its normal activities of food gathering, mating, and caring for young’ (Burt 1943; cited by: Samuel and Garton 1985; White and Garrott 1990; Otis and White 1999; Roshier and Reid 2003), and is usually described as a numerical estimate of the area used by an animal (White and Garrott 1990). An important addition to this definition is a timeframe of interest (Otis and White 1999). Other important activities occurring within the home range include breeding, predator evasion, shelter/exposure seeking, play and territory defence (Roshier and Reid 2003). Home range for most Australian bush birds is also poorly known over any timeframe. The methods of describing home range are many, but a few appear to have been accepted more widely than others. By far the easiest and most widely used is the minimum convex polygon (MCP), which draws a polygon around the locations (fixes) of an animal which surround the greatest area. Their wide use makes them one of the few methods useful for comparison between studies (White and Garrott 1990). A widespread criticism of MCP is that the MCP includes large areas not used by the animal (Kenward 1987; White and Garrott 1990; Kenward et al. 2003). White and Garrott (1990) argue that the word ‘normal’ in the definition of home range is important and that some means of excluding data from excursions outside the ‘normal’ home range is needed during analysis. However, it appears that many animals do undertake excursions, and excluding such data without knowledge of the reasons for undertaking excursions is likely to provide an underestimate of the area needed by the animal. A more valid criticism of MCP is that they give no indication of how intensively different areas of the range are used (Kenward 1987; White and Garrott 1990; Rodgers and Carr 1998; Kenward et al. 2003). Both these criticisms are overcome to some extent by more sophisticated methods of determining home range, such as harmonic mean (Dixon and Chapman 1980) or kernel (Worton 1989) analysis. This chapter presents data on the movements of individual Melithreptus and P. novaehollandiae, at a number of sites within the Mt Lofty Ranges, with a focus on short time frames (less than a month). Comparisons are made with a focus on differences within the small Melithreptus guild and between Melithreptus and P. novaehollandiae. 122 Radio-tracking was used to determine the movements of individual birds as this method allows data to be collected on where the bird goes, not where the researcher goes, as is commonly the case with other methods (mist-netting, colour-banding). 123 Table 5.1: Summary of radio-tracking studies on Australian honeyeaters Phylidonyris novaehollandiae and P. nigra results were not distinguished in the studies listed. * Maximum distance moved given only if dispersal occurred, mean given is for three birds which dispersed. Days Distance (km) Species Transmitter weight (grams) Mean Max Mean Max n Study P. novaehollandiae and P. nigra 1.5 – 1.6 2.4 5.3 - - 15 O'Connor and Pyke (1987) P. novaehollandiae and P. nigra 1.5 – 1.6 6.6 - - - 93 Pyke and O'Connor (1993) Lichenostomus melanops cassidix 1.7 – 2.3 32 43 *12.7 20.4 12 Runciman et al. (1995) Manorina melanocephala 2.0 – 2.5 30 51 3.4 5.6 10 Clarke and Schedvin (1997) Table 5.2: Results of some home range studies on Australian honeyeaters A – adult. J – juvenile. B – breeding adult in the non-breeding season. N – non-breeding adult in the non-breeding season. HMC is Harmonic Mean Contour. MCP is Minimum Convex Polygon. 1Locations were only used if they were ‘on grid’ – the 90% MCP relates only to those points that were already within the defined grid, ignoring those fixes (number or % not given) that were outside this area. 19 of 93 bird had sufficient information for the analysis. Home range Species Sex Age Type Radio-tagged ha Type % n Study L. melanops cassidix ♂ A B No 0.39 HMC 80 6 ‘Mauve’ site. Moysey (1997) L. melanops cassidix ♀ A B No 0.30 HMC 80 6 ‘Mauve’ site. Moysey (1997) L. melanops cassidix ♂ A B No 0.24 HMC 80 5 ‘Green’ site. Moysey (1997) L. melanops cassidix ♀ A B No 0.21 HMC 80 5 ‘Green’ site. Moysey (1997) L. melanops cassidix ♀&♂ A N No 0.28 HMC 80 5 ‘Green’ site. Moysey (1997) L. melanops cassidix ♀&♂ J No 0.51 HMC 80 4 ‘Green’ site. Moysey (1997) P. novaehollandiae and P. nigra ♀&♂ A Yes 10.48 MCP 90 19 Pyke and O'Connor (1993) 124 5.2 Methods The movements of Melithreptus were investigated at four sites in the Mt Lofty Ranges: Scott Conservation Park, Kaiser Stuhl Conservation Park, Scott Creek Conservation Park and Newland Head Conservation Park.