May Meeting

Wed 12 May 2021 07:30pm

Geoffrey Dabb - Mysteries of the Glossy Black-Cockatoo
Michael Guppy - Home-range sizes of 11 bird species on a 10 ha site in South-east Australia

The first presentation will be by Geoffrey Dabb on the “Mysteries of the Glossy Black-Cockatoo.” These include: How could anyone think it is glossy? Why does it visit Canberra? What does it prefer to eat, really?

The main presentation will be by Michael Guppy and is entitled “Home-range sizes of 11 bird species on a 10 ha site in South-east Australia.”

The study we (Michael and co-workers Sarah Guppy, Philip Withers, Anthony Overs and Richard Marchant) present here, for a community of both permanent residents and seasonal visitors, on our Moruya site, was designed to produce long-term, comprehensive and unambiguous sighting data for individuals from a variety of species in the same habitat. For 7-9 breeding seasons (depending upon the species), sightings of multiple, colour-banded breeding individuals, of both sexes, from 11 species, were recorded and used to calculate home-range sizes. A novel method of quantifying relative and actual home-range size was developed, that allows rapid and simple calculation, and analysis. These data have enabled us to address three questions. First, what, if any, external factors are related to home-range sizes on the site? The factors we investigated were year, the Southern Oscillation Index, and pair numbers. Second, are there inherent differences in home-range sizes, both within species (males vs females), and between species? Third, how do our home-range sizes compare with those in the literature for the same species. The results are unexpected and puzzling, and have forced us to completely re-think the factors that determine the sizes of the home ranges on this site.

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