Foraging distances and habitat preferences of a recent urban coloniser: The Australian white ibis: Fid-Bau Portal

Foraging distances and habitat preferences of a recent urban coloniser: The Australian white ibis

Martin, John M. / French, Kris / Ross, Geoffrey A. / Major, Richard E.

Highlights ► The Australian white ibis is a recent urban coloniser that has modified its foraging behaviour to exploit landfills. ► Ibis were radio-tracked making return foraging trips of 70km and multiple movements of up to 58km. ► The majority of foraging movements were localised and less than 20km. ► Population management (nest and egg destruction) is likely to result in displacement of colonies within the immediate (<10 km) area. ► The recognition of key colonies as refuges will be important for resolving human-ibis conflicts and ensuring a sustainable population.

Abstract Australian white ibis populations have increased in many urban areas while traditional inland populations have declined. In instances where conflicts have occurred land managers have been licensed to remove nests and eggs and cull adults at a site scale. With the increase in urban populations and local management of the species, there is a need to understand how ibis are using urban resources and how they move through the urban landscape to identify important resources. To gain a better understanding of the connectedness of local urban populations, we fitted 82 birds with radio transmitters at three common habitats: an urban park, a breeding colony and a landfill. Over a period of 48 weeks we found 45% of birds made movements greater than 10km, with 13% moving greater than 30km. Ibis were located at up to nine foraging and seven roost sites, demonstrating the connectedness of the population across the study region. Landfills were identified as a major food resource with 63% of ibis (n =82) located therein, while parks supported local foraging with only 27% of ibis (n =82) located therein. Our results indicate that ibis showed site fidelity but also interacted on a regional scale within approximately 40km of their colonies. Accordingly, conservation planning for this species needs to be assessed on a regional basis, not on a localized case-by-case basis. However, further research into the limits of the ‘region’ is required for this highly mobile colonial species.