Time since fire influences macropod occurrence in a fire‐prone coastal ecosystem

Abstract

Knowledge of animal responses to fire is fundamental to wildlife management in fire-prone ecosystems. Fire can influence the occurrence of large herbivores by altering the structure and composition of vegetation. However, how fire affects herbivore occurrence in many ecosystems is poorly understood. Large herbivores may be attracted to burnt areas due to higher foraging quality. Conversely, herbivores may avoid burnt areas due to heightened predation risk. We tested the influence of vegetation type and fire history variables on the occurrence of macropods at Booderee National Park in south-eastern Australia. We documented macropod occurrence at 107 long-term monitoring sites using spotlighting surveys conducted between 2003 and 2019. We modelled relationships between the occurrence of the eastern grey kangaroo (Macropus giganteus) and the swamp wallaby (Wallabia bicolor) with three fire history variables; time since fire, fire frequency and burn context (the proportion of the area surrounding each site that was recently burnt), as well as their interaction with vegetation type. We found both macropod species selected recently burnt sites, likely due to a higher abundance of preferred plants at these sites. Increasing fire frequency was associated with a reduced occurrence of the eastern grey kangaroo. The occurrence of both macropod species was significantly higher in forest sites, possibly reflecting higher foraging quality of grass and shrub species compared to woodland, heathland and shrubland sites. We suggest that if fire is used as a management tool, it is important to recognise potential feedbacks from increased foraging pressure from large herbivores. Future fire management will need to avoid burning areas of sensitive vegetation if local herbivores display pyric herbivory responses, and/or avoid small-scale burns, which may concentrate foraging pressure.

How do invasive predators and their native prey respond to prescribed fire?

“…We did, however, find that swamp wallaby activity was higher in areas with fewer years since fire, a result consistent with other research showing this species' preference for early successional vegetation (Chard et al., 2022 ; Styger et al., 2011 ). This initially seems contradictory to our observed decline of wallaby activity after the prescribed fire.…”

Modeling mammal response to fire based on species’ traits

“…These almost certainly represent behavioral responses to fire, rather than changes in population size. Macropods are known to be attracted to fresh grass growth in recently burned areas (Chard et al., 2022; Styger et al., 2011). Indigenous Australians burned patches of vegetation to encourage kangaroos and wallabies to feed in the area and increase hunting success (Yibarbuk et al., 2001).…”

Post‐fire pickings: Large herbivores alter understory vegetation communities in a coastal eucalypt forest

“…Of the three macropod species, the eastern grey kangaroo and the swamp wallaby are the most common in Booderee National Park (Chard et al, 2021 ). While density measures have not been conducted for any macropod species, previous research analyzing conditional abundance of the swamp wallaby peaked between 2007 and 2013 compared to when surveys began in 2003 (Lindenmayer et al, 2016 ).…”

“…The swamp wallaby is a browsing species that will forage on most understory plants in a forest community with a preference for forb species (Di Stefano & Newell, 2008 ). For more detailed descriptions on each species preferred plant foods see Chard et al ( 2021 ).…”

“…Furthermore, managers have been concerned with the growing population of macropods in Booderee National Park (Dexter et al, 2013). Previous research in the study area found both species preferentially selected forest vegetation communities (Chard et al, 2021). The eastern grey kangaroo is a grazing species, targeting grass species such as Imperata cylindrica and Themeda triandra (Brunton et al, 2018).…”