Recently but infrequently burnt breeding sites are favoured by threatened Gouldian finches (Erythrura gouldiae)

Abstract

Frequent and extensive fires are becoming increasingly common throughout the tropical savannas of northern Australia. This fire regime has been implicated in both habitat alteration and losses of biodiversity. Granivorous birds are particularly affected because of the effect of fire on grass seed availability. The endemic Gouldian finch (Erythrura gouldiae) has experienced population declines in recent decades, potentially in response to changed fire regimes. Using breeding data from monitored artificial nest-boxes, this study examined the choice of breeding site by Gouldian finches in response to several attributes of the prevailing fire regime. The fire regime was characterised using remote sensing analysis of annual fire scars. Time since last fire and fire frequency were the most useful predictors of breeding site occupancy. Gouldian finches favoured recently burnt sites (previous dry season), but also sites that were infrequently burnt (return time of 2–3 years). Consequently, under the current regime of many frequent fires, Gouldian finches move among breeding sites and display low seasonal site fidelity. Our findings provide support for the notion that the Gouldian finch favours a fine-grain patch-mosaic fire regime and that contemporary large-scale fire regimes are likely contributing to their decline.

Fire regime effects on annual grass seeds as food for threatened grass-finch

“…On average, 60% of the Wyndham region was burned annually and >50% was burnt 5 to 6 times within nine years (Weier et al 2016). Considering the relatively limited effect that the frequency of fire has on the density, fecundity, and seed abundance of annual Sorghum spp., it is unlikely that the current frequent fire regime will cause an appreciable impact or limitation on S. stipoideum seed availability to Gouldian finches during the breeding period (March to July; Weier et al 2018).…”

“…Lower frequency of early dry season fires was found to maximize nutritional content of Sorghum spp. seeds available to Gouldian finches (Weier et al 2017) and likely influenced choice of breeding sites (Weier et al 2016). Studies of breeding success in Gouldian finches also highlighted the influence of regional fire size and fire number in determining breeding success.…”

“…Recent studies have suggested that Gouldian finch breeding success is related to fire regimes that promote production of annual Sorghum spp. seeds of higher nutritional quality (Weier et al 2016(Weier et al , 2017. Conversely, it is known that nutritional stress can delay breeding, resulting in fewer, smaller offspring (Pryke et al 2012).…”

“…grass seed availability is an important criterion in breeding habitat selection by Gouldian finches (and other grass finch species) in northern Australia (Dostine et al 2001, Brazill-Boast et al 2011, Weier et al 2016, Weier et al 2017. Weier et al (2016) and Weier et al (2017) found that the most successful finch breeding occurred at recently but infrequently burned sites where Sorghum spp. seeds had greater nutritional quality.…”

Changing Fire Regimes in Tropical and Subtropical Australia

“…Further fire frequency is expected to increase due to invasion by these grasses as they have the potential to support fire more than once a year. In native ecosystems seasonal burns are patchy and limited in extent due to the discontinuous nature of the fuel loads and fire weather (Whelan 1995;Weier et al 2017). However Guinea, Gamba and Mission grasses are expected to increase the continuous fuel load substantially, which in turn will increase the probability of uniform fires over extensive areas.…”