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4.2 Response of fauna to fire - Acknowledgements IV Summary V 1 Introduction 1 2 Methods 2

4.2 Response of fauna to fire


The fauna data collected during this project has been summarised to allow a basic comparison between areas burnt in 2009 and those long-unburnt, with some exploration of fire frequency. Further statistical analysis of these aspects is planned and will be incorporated into reports for other fire ecology studies being conducted by ARI.

Data from cameras have given an indication of the presence of certain species within the study areas, confirming their persistence at sites of a particular fire history. The proportion of sites where particular species were detected during this study is likely to be an underestimate of the true proportion as it is possible that species may not be photographed despite actually being present (Nelson and Scroggie 2009). Further analyses are planned to quantify this effect.

Given the preliminary nature of the data analyses it should be noted that interpretations of the results are tentative, and a more comprehensive exploration may lead to different conclusions.

4.2.1 Ground-foraging mammals


All 18 mammal species detected during automated camera surveys are generally widespread and common in Victoria (Menkhorst 1995e). Many of the records obtained during this study have added valuable information about the distribution and occurrence of particular species in the areas surveyed. The Mountain Brushtail Possum, Bush Rat, Dusky Antechinus and Long-nosed Bandicoot have been recorded within the Beechworth study area at only a few locations prior to the current study. Their detection during this study is an important confirmation of their presence in the area, as these records fall along the north-western edge of their known range in Victoria. The Common Brushtail Possum has not been previously recorded in the Beechworth forests surveyed during this study, although they are known to be present in the wider area.

A higher diversity of mammals was detected in the Beechworth area than at Taggerty. However, all of these species have also previously been recorded from the Taggerty area (DSE 2007). Indeed, existing records suggest that the Bush Rat, Dusky Antechinus and Long-nosed Bandicoot are more widespread near Taggerty, but they were not detected by the survey cameras on this occasion. This may be due to images in photos not being clear enough for identification, cameras not being triggered, or their absence from the site.

A study conducted in the southern end of the Black Range found densities of Bush Rats and Agile Antechinus to be much reduced in areas burnt in 2009 compared to adjacent unburnt forest (Banks et al. 2011a).

Cameras may have been situated in non-preferred habitat for some species, decreasing the likelihood of detection. The Dusky Antechinus is known to prefer damp habitats with a dense vegetation cover (Menkhorst 1995b), which was not targeted during this study. Most of the areas surveyed would also not be considered preferred habitat for the Long-nosed Bandicoot, which is found in areas where there is a dense understorey or ground cover usually associated with damp or riparian areas including thickets of introduced species such as blackberry (Menkhorst and Seebeck 1995). During the current study, this species was recorded close to Lake Kerferd where there were scattered dense thickets of blackberry.

Mountain Brushtail Possums were recorded at more sites than Common Brushtail Possums near Taggerty, reflecting previous records in the area. Although these two possum species do sometimes occur together, their habitat preferences differ in that the Mountain Brushtail Possum is usually found in wetter forest types than the Common Brushtail Possum, or in gullies in drier forests (Menkhorst 1995a, 1995f).

There have been no formal records of House Mouse and deer from the Beechworth forests surveyed (DSE 2007), which undoubtedly reflects a lack of survey effort. Sambar Deer have been recorded 35 km to the south, near Bright, and anecdotal evidence suggests they are becoming more common in the broader area.

Most species were recorded from only a small number of sites, in both recently burnt and long-unburnt forest, which makes comparison between fire histories difficult. This small number of site records could be due to low detection probabilities, low animal densities, or unsuitable bait used to attract fauna to the cameras. For example, carnivores such as House Cats may be more readily attracted to bait containing meat rather than the herbivore bait used here.

Sixteen of the species recorded were found in areas burnt in 2009, demonstrating their ability to persist after these fires. Mammals may survive during fire by sheltering in vegetation, burrows, hollow trees and logs or in unburnt patches, or by avoiding the fire front. They may then recolonise an area after fire by moving in from nearby unburnt areas (Whelan et al. 2002, Garvey et al. 2010). Herbivores, such as macropods, can take advantage of regrowth as a food source soon after fire (Christensen and Kimber 1975), which may help them recolonise or reach areas where food is more plentiful. The Common Wombat and Black Wallaby were present at nearly every site, suggesting little or no preference between unburnt habitat and areas burnt in the 2009 fires. Common Wombats increased their home range in burnt alpine areas and foraged further from their burrows when food was scarce (Green and Sanecki 2006) and may have adopted a similar strategy here. Black Wallabies have been found to move away from approaching fires and either take refuge in creeklines or double back through the fire front to find shelter in areas already burnt. The severity of the fire may determine whether they remain in the area post-fire or migrate to other areas, with low intensity fire less likely to result in individuals moving away (Garvey et al. 2010). Most of the sites surveyed in the current study were not severely burnt, and those that were severely burnt were not far from such areas.

Fire can reduce the availability of tree hollows which may have particular consequences for hollow-dependant possums (Inions et al. 1989). However, in certain situations some species may be more flexible to changes in resources than others. In 2009, burnt Mountain Ash Eucalyptus regnans near Camberville, Mountain Brushtail Possums were observed to find sufficient hollows in the short term by altering den preferences (Banks et al. 2011b). This was after a reduction in available hollows of over 80%. Both Common and Mountain Brushtail Possums have been known to use other habitat for shelter when hollows are limited, such as logs and burrows made by other animals (Menkhorst 1995a, 1995f). In contrast, both Brushtail species were not detected from sites within Bunyip State Park after the sites had been burnt during the ‘Black Saturday’ fires (E. McNabb pers. comm.). During the current study Common Brushtail Possums were at more long-unburnt sites compared with recently burnt areas, while Mountain Brushtail Possums showed no discernible difference.

Although the Long-nosed Bandicoot and Common Ringtail Possum were only recorded from unburnt sites, they were recorded from too few sites to be able to attribute this as an effect of fire. Common Ringtail Possums are not as readily captured on automated cameras as some other species and they were known to occur at several locations within the study areas before 2009 (DSE 2007). Their current status at these locations is unknown.

The House Mouse is known to successfully colonise areas soon after fire (Friend 2003, Kelly et al. 2011). Although they were only present at a low number of sites during the current study, all these sites were in recently burnt forest. Their colonisation of recently burnt areas is thought to be due to their ability to survive in burrows, their high reproductive rate and their generalist foraging (Menkhorst 1995d), and ability to take advantage of high seed fall after fire (Friend 2003). However, the exact nature of the relationship between time since fire and their presence is sometimes unclear (Kelly et al. 2011). The Red Fox was also found at more sites that were recently burnt than long-unburnt, suggesting that native species in burnt areas may be under increased predation pressure. The European Rabbit showed the opposite response to fire than the other introduced species discussed above, appearing at proportionally more sites in long-unburnt forest. There are many records of rabbits within the Black Range prior to the 2009 fires however, none were recorded there during our study. It is unclear whether fire has been a major factor in their distribution across the current study areas or whether location also had some influence. Within Taggerty, rabbits were only recorded from unburnt forest sites, which were also close to grassed areas (camping grounds or a fuelbreak). At Beechworth, they were found at both unburnt and recently burnt sites, particularly from several sites that were within a few kilometres of each other. European Rabbits are widespread throughout Victoria and spread into forests particularly via roads, feeding on grassy verges and making burrows where the soil conditions are suitable (Menkhorst 1995c). Although rabbits disperse readily and recolonise formerly occupied areas (Parer 1982, Menkhorst 1995c), their relationship with fire-affected areas is unclear.

Fire frequency within recently burnt forest did not appear to have an effect on the presence of mammals detected during this study, with the possible exception of the Short-beaked Echidna. This species is well adapted to a wide range of habitats and conditions, including those brought on by disturbances such as fire (Menkhorst 1995g), although a reduction in logs may have a negative impact (Tolsma et al. 2007).

4.2.2 Insectivorous bats


There is little information about the influence of fire events on insectivorous bat activity in Australian forests. Limited research overseas has focused mainly on prescribed burning and suggests that bat responses are linked to flight manoeuverability and prey availability. These studies showed either an increase in bat activity levels in burnt areas, which was thought to be related to a more open forest structure (Smith and Gehrt 2010) or no difference between burnt and unburnt areas (Loeb and Waldrop 2008). The density and structure of forest vegetation can influence how individual bat species fly and navigate through their habitat with some species favouring more open areas (Law and Chidel 2002). Radiotracking of foraging bats found them more often in burnt than unburnt habitats, and coincided with differences in insect abundance (Lacki et al. 2009), although the exact nature of these relationships remains unclear. Bat activity as measured near Taggerty and Beechworth showed the opposite effect, with unburnt areas supporting higher bat activity. Although fire may simplify the understorey in the short term, subsequent regrowth can impede the mobility of bats, and they may avoid such areas. In addition, mortality and injury during and immediately after a bushfire is likely to reduce wildlife populations (Whelan et al. 2002), and bat numbers in these areas may not have recovered to pre-fire levels.

Another study, project 29 within the ‘Rebuilding Together’ program has also explored the impact of the 2009 fires on bat activity, with over 60 sites surveyed (Jemison et al. in prep.). Analysis from that study supports the findings of those presented here.

4.2.3 Diurnal birds


Previous studies in Victorian forests have shown that birds generally decline soon after severe fire (Reilly 1991, Loyn 1997) and then return at varying rates as habitat regenerates. Birds that favour open understorey may prosper in the early years, moving into habitats such as gullies where unburnt vegetation is usually too dense to accommodate them. However, those same species may subsequently decline as prolific shrub regrowth leads to a much more densely vegetated habitat (Loyn 1997). These responses can be discerned in results of the current study, which was conducted two years after the 2009 fires. By this time, the understorey had become dense at some sites but remained sparse at others, and responses varied accordingly. In general the study shows that bird populations were reduced by fire in the short term, in line with previous work. Hence frequent fire is likely to be detrimental to bird populations as a whole, and this also applies to the majority of bird species and guilds. However, some species appeared to favour recently burnt sites, admittedly in such low numbers that results are unlikely to prove statistically significant. For some of those species there is corroborating evidence that they may favour recently burnt habitats. For example, White-winged Choughs were only found in recently burnt sites in similar Forby Forest in the Wombat State Forest (Loyn et al. 2003), although they are widespread regardless of fire history in drier types of forest such as Box-ironbark (Loyn 1985). Sulphur-crested Cockatoos are usually associated with open country, and it is likely that fire has opened up the forest sufficiently to allow them to occupy it in the early years after fire. Species such as these may be expected to benefit from frequent fires in parts of the forest.

The study produced no evidence that introduced birds proliferate after fire. On the contrary, the only records of introduced birds during formal counts were of Common Blackbirds at one long-unburnt site at Taggerty with dense thickets of introduced blackberry. Other species were seen nearby (e.g. flocks of European Goldfinches in cleared pine plantations), but not in burnt or unburnt forest. Introduced birds are generally common in farmland and towns but not in forest (Loyn 1985), and this study shows that this remains the case in terms of forest even when it is burnt.
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