Impacts of fire on Sorghum stipoideum and subsequent influence upon breeding in the Gouldian finch (Erythrura gouldiae)

Abstract

The Gouldian finch (Erythrura gouldiae) is an endangered bird endemic to the savannas of northern Australia. Changed fire regimes have been proposed as one of the prominent causes of decline in this species and many other granivores. The contemporary fire regime consisting of severe, frequent and extensive fire is implicated in a reduction of grass species abundance and diversity, and possibly food availability to granivores throughout the tropical savannas of northern Australia. Gouldian finches are particularly affected due to their restricted diet, which consists almost solely of annual Sorghum grass seed throughout the dry season and breeding season. This thesis has examined the effect of fire on the nutritional quality and quantity of annual grass Sorghum stipoideum seeds as a possible mechanism underpinning breeding site choice in response to fire by Gouldian finches. Gouldian finch breeding sites were monitored in the north east Kimberley region of Western Australia. Breeding site choice in response to fire was determined using nest-box occupancy and fire history at each site. The effect of fire on Sorghum seed phenology, abundance and nutritional quality were investigated. The research found that Gouldian finches choose breeding sites that were recently but infrequently burnt, and the initiation of breeding was timed with the availability of Sorghum seed locally. Further, site selection by the finches was associated with the higher availability and nutritional quality of the Sorghum seeds. Sorghum seeds were most abundant and nutritious in areas that have been recently, but infrequently burnt, which parallels the findings pertaining to breeding site choice. Research from this thesis illustrates the mechanisms by which altered fire regime may be impacting upon the Gouldian finches. This information will assist by informing fire management in areas with known Gouldian finch breeding populations.

Date of Award	Aug 2017
Original language	English
Supervisor	Hamish Campbell (Supervisor)