Effects of time since fire on birds: How informative are generalized fire response curves for conservation management?

Abstract

Fire is both a widespread natural disturbance that affects the distribution of species and a tool that can be used to manage habitats for species. Knowledge of temporal changes in the occurrence of species after fire is essential for conservation management in fire-prone environments. Two key issues are: whether postfire responses of species are idiosyncratic or if multiple species show a limited number of similar responses; and whether such responses to time since fire can predict the occurrence of species across broad spatial scales. We examined the response of bird species to time since fire in semiarid shrubland in southeastern Australia using data from surveys at 499 sites representing a 100-year chronosequence. We used nonlinear regression to model the probability of occurrence of 30 species with time since fire in two vegetation types, and compared species' responses with generalized response shapes from the literature. The occurrence of 16 species was significantly influenced by time since fire: they displayed six main responses consistent with generalized response shapes. Of these 16 species, 15 occurred more frequently in mid- or later-successional vegetation (> 20 years since fire), and only one species occurred more often in early succession (< 5 years since fire). The models had reasonable predictive ability for eight species, some predictive ability for seven species, and were little better than random for one species. Bird species displayed a limited range of responses to time since fire; thus a small set of fire ages should allow the provision of habitat for most species. Postfire successional changes extend for decades and management of the age class distribution of vegetation will need to reflect this timescale. Response curves revealed important seral stages for species and highlighted the importance of mid- to late-successional vegetation (> 20 years). Although time since fire clearly influences the distribution of numerous bird species, predictive models of the spatial distribution of species in fire-prone landscapes need to incorporate other factors in addition to time since fire.

Relationships between time since fire and honeyeater abundance in montane heathland

“…Numbers of White-eared Honeyeaters were seasonally low in Blue Mountains Heath. This species showed no response to time since fire in Chenopod Mallee and a bell-shaped response in Triodia Mallee over 100 years (Watson et al 2012). Although relationships detected in both studies showed various trends, in all cases the abundance of these honeyeater species increased over the 40-year period following fire in these habitats.…”

“…Different types of relationships between certain honeyeater species and time since fire were also detected in Murray Mallee vegetation communities (Watson et al 2012). Abundance of the Spiny-cheeked Honeyeater (Acanthagenys rufogularis) and the Striped Honeyeater (Plectorhyncha lanceolata) after fire showed a linear trend that was comparable to that of the New Holland Honeyeater in the cool season in Blue Mountains Heath.…”

“…The resulting variations in avian community composition may be associated with post-fire successional changes in vegetation communities, and similar species might find a certain range of time since fire more useful in a habitat (Lowe et al 2012;Pons et al 2012). Australian studies, such as those by Loyn (1997) and Watson et al (2012), have also found that some bird species may occur in higher numbers in habitat representing specific ranges of time after fire. Time since fire is thus an aspect of the fire regime that can play an important role in shaping avian diversity at the landscape scale.…”

The impacts of fire on birds in Australia's tropical savannas

“…Bird species associated with long unburnt vegetation include Malleefowl (Leipoa ocellata), the abundance of which generally increases in mallee woodlands to at least 40-60 years after fire (Benshemesh 1990;Watson et al 2012a), Noisy Scrub-bird (Atrichornis clamosus) (Burbidge 2003), Eastern Bristlebird (Dasyornis brachypterus) (Bain et al 2008) and Black-eared Miner (Manorina melanotis) (Clarke et al 2005). Ecological traits associated with such preference include limited dispersal ability (rendering subpopulations particularly susceptible to extirpation in a single extensive fire, with such areas then unlikely to be recolonised), a propensity for foraging in dense leaf litter, and a propensity for foraging on the ground or in low shrubs.…”

Drivers of diversity at the local- and landscape-scale in a fire-prone landscape

“…Much research in fire ecology to date has focused on the response of biota to temporal aspects of the fire mosaic, such as changes in biota with time since last fire (Zammit and Zedler 1988;Morgan and Lunt 1999;Keeley et al 2005;Watson et al 2012). However, there has been increasing interest in how spatial patterns of fire impact on biota (Bradstock et al 2005;Parr and Andersen 2006).…”