Automated VHF telemetry reveals Gouldian Finches increase ranging behaviour in response to resource scarcity: implications for conservation management

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ABSTRACT The Gouldian Finch (Chloebia gouldiae) relies on an annual crop of seed from Sorghum spp. and is hypothesised to face a bottleneck as this resource declines in the late dry season. This periodical seed-scarcity aligns with a reported decline in sightings, low recapture rates and an increased stress-hormone response in the species, raising concerns of increased mortality at this critical time of year. A change in behaviour in line with Optimal Foraging theory could instead explain the absence of the species from key habitats at this time of year. To test this hypothesis, we monitored the movements of 38 Gouldian Finches across a 120 km2 area using passive VHF-telemetry during periods of high and low resource availability. Our observations revealed that tagged Gouldian Finches foraged intensively within patches and infrequently moved between them in times of abundant seed. As resources declined throughout the north Australian dry season, tagged birds reduced foraging time within a patch and actively sought out new resource patches. These findings are consistent with the hypothesis that Gouldian Finches adapt to grass seed scarcity by increasing their ranging behaviour. Conservation management strategies such as prescribed burning to achieve a fine-grain mosaic of grass seed diversity regionally could mitigate the need for extensive dispersal, improving conservation outcomes for the Gouldian Finch population.