Date of Award

2008

Degree Type

Thesis

Degree Name

Master of Science

School

School of Natural Science

Faculty

Computing, Health and Science

First Advisor

Professor William Stock

Abstract

Conservation planning for animal species inhabiting modified landscapes requires understanding of where animals occur and how they utilise both natural and modified habitats. In this study the distribution and foraging behaviour of the forest red-tailed cockatoo (Calyptorhynchus banksii naso), Baudin’s cockatoo (C. baudinii) and Carnaby’s cockatoo (C. latirostris) was investigated in three study areas which each contained a different combination of modified habitats. Pickering Brook contained native forest and orchards, Wungong contained a mosaic of native forest and revegetation, while Karnet contained primarily native forest and paddocks. The relationship between cockatoo distribution and land use types was examined by constructing Generalised Linear Models based on bird counts and land use data along 90.5 km of road transects. The Akaike Information Criterion (AIC) was used to select a set of the most parsimonious candidate models. Models were constructed at two scales: Regional models incorporated the datasets of all three study areas, while study area models used the datasets of single study areas. Models for the forest red-tailed cockatoo indicated selection against young post-1988 revegetation. This response was apparent at both the regional scale and within the Wungong study area. Baudin’s cockatoo selected in favour of orchards at the regional scale, but their distribution was unrelated to any land use variable within the (orchard-rich) Pickering Brook study area. No models were constructed for Carnaby’s cockatoo due to a limited number of observations for this species. Feeding observations demonstrated the importance of the native eucalypts marri (Corymbia calophylla) and jarrah (Eucalyptus marginata) as a food source for the forest red-tailed cockatoo and Baudin’s cockatoo. In contrast Carnaby’s cockatoo fed most frequently in plantations of introduced pine (Pinus spp.). Contrary to model predictions, Baudin’s cockatoo was never observed feeding in apple orchards during the study. This discrepancy may be due to timing of the surveys outside the hours when Baudin’s cockatoo fed in orchards, or it could indicate that orchards are of limited importance as a food source. Forest red-tailed cockatoos consistently fed on particular marri trees while ignoring others, but this selectivity was unrelated to fruit morphology or seed nutrient content. Instead, foraging patterns may have been driven by ingrained habits, or by variation in the concentration of secondary compounds. iv In conservation efforts, identification of critical habitats is an important first step. This study highlighted the importance of studying habitat selection and constructing management plans at an appropriate scale, relative to the range of the target species. Wide ranging species like black cockatoos require regional scale protection of important broad vegetation types such as the northern jarrah forest, combined with landscape scale protection and restoration – for instance during postmining revegetation – of specific feeding habitat and food species, such as pine for Carnaby’s cockatoo and possibly Fraser’s sheoak (Allocasuarina fraseriana) for the forest red-tailed cockatoo.

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