Feeding profitability is associated with Glossy Black-cockatoo (Calyptorhynchus lathami ssp. lathami) feed tree selection

ABSTRACT

Habitat modification and destruction are known to be responsible for declines in avian taxa. Specialist species such as the vulnerable Glossy Black-cockatoo (Calyptorhynchus lathami ssp. lathami) are particularly at risk due to the limited number of Casuarina and Allocasuarina species on which they feed, which is compounded by their propensity for selecting only specific individual feed trees within patches. This study aims to address the lack of understanding surrounding Glossy Black-cockatoo feeding ecology in southeast Queensland, Australia, by examining determinants of tree selection for Allocasuarina littoralis and A. torulosa. We conducted surveys to identify feed and non-feed trees of both Allocasuarina species, and differences between the physical and chemical characteristics of trees, cones, and seeds were investigated. We found that larger trees were preferentially foraged, with nutritional profitability as the primary factor governing tree selection. Feed tree cones had higher seed number and seed mass, with seeds containing higher levels of fatty acids and nutrients than non-feed tree cones. We conclude that further research should aim to delineate the factors contributing to these differences, alongside determining appropriate management strategies to support viable feeding habitat, which is most likely comprised of mixed age patches, capable of maintaining mature trees offering sufficient nutrient reward.

KEYWORDS:

• Feeding ecology
• cockatoo
• Allocasuarina
• threatened species
• dietary specialisation
• feeding profitability
• monophagy
• foraging

Acknowledgements

We gratefully acknowledge Dr Peter Brooks, Dr Trong Tran, Tracey McMahon, Tsvakai Gama, Dr Shahla Hosseini Bai, Michael Nielsen and David Appleton for their assistance during nutrient and fatty acid analyses. Fieldwork planning was assisted greatly by Penn Lloyd, Liz Gould, Keith McKosh and Tracey Larkin from the Glossy Black Conservancy, as well as Bob Carey, Tim Lennon, and Joe Skok in providing their valuable local knowledge. The support of Queensland National Parks and Wildlife and Noosa Council is also gratefully acknowledged.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplementary material

Supplemental data for this article can be accessed here.

Additional information

Funding

This work was supported by Birds Queensland; The Glossy Black Conservancy; and the University of the Sunshine Coast.