CSIRO PUBLISHING www.publish.csiro.au/journals/wr Wildlife Research, 2008, 35, 33–43 The short-term effects of an extensive and high-intensity fire on vertebrates in the tropical savannas of the central Kimberley, northern Australia Sarah Legge A,C,D , Stephen Murphy A , Joanne Heathcote A , Emma Flaxman A , John Augusteyn B and Marnie Crossman B A Australian Wildlife Conservancy, Mornington Wildlife Sanctuary, PMB 925, Derby, WA 6728, Australia. B Queensland Parks and Wildlife Service, PO Box 3130, North Rockhampton, Qld 4701, Australia. C Australian National University, Canberra, ACT 0200, Australia. D Corresponding author. Email: sarah@australianwildlife.org Abstract. We report the effects of an extensive (>7000 km 2 ), high-intensity late-dry-season fire in the central Kimberley, Western Australia, on the species richness and abundance of mammals, reptiles and birds. Five weeks after the fire we surveyed 12 sites (six burnt, six unburnt); each pair of sites was closely matched for soil type and vegetation. The species richness and abundance of mammals and reptiles was greater at unburnt sites, especially for mammals (with a 4-fold difference in abundance between burnt and unburnt sites). There was an indication that reptiles immigrated into unburnt patches, but mammals did not. There were also species-specific responses to the fire: Rattus tunneyi and Pseudomys nanus were much more abundant in unburnt sites, whereas Pseudomys delicatulus was caught in equal numbers at burnt and unburnt sites. Diurnal reptiles were more abundant at unburnt sites, but nocturnal reptiles were equally common at burnt and unburnt sites. Avian species richness and overall abundance was similar between burnt and unburnt patches, although a few species showed preferences for one state or the other. The overall high trapping success for mammals (18% across all sites; 28% in unburnt patches) contrasts with the well documented mammal collapse in parts of northern Australia and seems paradoxical given that our study area has experienced the same increase in fire frequency and extent that is often blamed for species collapse. However, our study area has fewer pressures from other sources, including grazing by large herbivores, suggesting that the effects of these pressures, and their interaction with fire, may have been underestimated in previous studies. Introduction A suite of studies in the tropical savannas of northern Australia single hot fire (Woinarski et al. 1999). The effects of particular has revealed widespread declines in a range of taxa, most fire regimes over the longer term are harder to assess, but the notably small to medium-sized mammals (Braithwaite and available evidence suggests substantial differences in the assem- Griffiths 1994, 1996; Maxwell et al. 1996; Woinarski et al. blages of flora and fauna in areas burnt frequently compared 2001; Price et al. 2005), seed-eating birds (Franklin 1999; with areas without fire (Bowman and Fensham 1991; Woinarski Franklin et al. 2005), and fire-sensitive vegetation (Russell- et al. 2004). Smith and Bowman 1992; Bowman and Panton 1993; Russell- In contrast to most savanna-dwelling taxa, there is mounting Smith et al. 2002). The introduction of cattle, cats and, in evidence from descriptive studies that small to medium-sized particular, an increase in the size and frequency of fires are most mammals from diverse taxa including rodents, dasyurids, often implicated (see references above). possums and bandicoots are relatively intolerant of any fire, Several descriptive studies and some controlled manipulative regardless of timing or intensity (Begg et al. 1981; Kerle and experiments have advanced our understanding of how fire Burgman 1984; Friend 1987; Kerle 1998; Firth et al. 2006). In affects various ecological processes and guilds in the tropical most cases, the declines occurred over the course of a year fol- savannas, including the phenology and population dynamics of lowing the fire (e.g. Begg et al. 1981; Kerle and Burgman woody vegetation, the productivity and composition of the grass 1984), suggesting that the indirect effects on survival and/or layer, and the responses of different faunal groups to fire events reproductive output from increased predation (from lack of and regimes (reviewed in Williams et al. 2003b). Over the short cover), and/or reduced resources (e.g. food, nesting) were more term (several years) many species of amphibians, birds and rep- important than direct fire-related mortality. This pattern is tiles appear resilient to different fire treatments although a few echoed in studies from other parts of the world (Whelan 1995; species show preferences for the extremes. For example, some Torre and Diaz 2004). The Kapalga fire experiment (Andersen granivorous birds preferentially use recently burnt habitats, but et al. 2003) imposed four fire treatments on entire subcatch- some blind snakes (Typhlopidae) may be sensitive to even a ments over five years and also showed that most mammal © CSIRO 2008 10.1071/WR07016 1035-3712/08/010033