Home Range and Habitat Selection of the Endangered Red Goshawk (Erythrotriorchis radiatus) Across Australia's Tropical Savannas.

The Red Goshawk (Erythrotriorchis radiatus) is Australia's rarest and most threatened raptor, having disappeared from approximately two-thirds of its breeding range and now persists across northern Australian tropical savannas. Despite this decline, its spatial requirements and habitat selections remain poorly understood within this environment, particularly in relation to anthropogenic disturbance. We conducted a long-term movement study across northern Australia (2015-2022), tagging adults and juveniles (n = 23 individuals; 67,142 locations). Home range size and habitat selection were analysed for 13 range-resident individuals using weighted autocorrelated kernel density estimators (wAKDE) and Resource Selection Functions (RSFs). Environmental covariates included both static (e.g., elevation, distance to water) and annually changing variables (e.g., habitat clearing, fire regime). Red Goshawks occupied extensive overall home ranges (mean 95% wAKDE = 601 ± 454 km2), with non-breeders requiring substantially larger areas (1229 ± 496 km2) than breeders (412 ± 221 km2). Breeding adults relied on well-defined core areas around nest sites (mean 50% wAKDE = 44.5 ± 27.1 km2). Habitat selection varied by breeding habitat: woodland breeders strongly select Eucalyptus tetrodonta woodlands relatively further from water, whereas riparian breeders avoid these woodlands, selecting long-unburnt vegetation closer to water; although riparian sample sizes were limited. On Cape York Peninsula, individuals tracked during active clearing of woodlands for mining largely avoided cleared and restored areas. Collectively, our findings demonstrate the extensive spatial requirements of Red Goshawks and provide preliminary evidence of ecological niche differentiation between breeding habitat types within tropical savannas, although further data are needed to fully resolve this. Avoidance of cleared and restored areas indicates limited short-term value of habitat restoration and provides a plausible mechanism linking habitat loss to the species' historical decline across its south-eastern range. Intact woodlands and riparian gallery forests emerge as key habitats supporting extant breeding populations.