Ecological specialisation in habitat selection within a macropodid herbivore guild
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Specialist species show stronger resource selection, narrower niches and lower niche overlap than generalist species. We examined ecological specialisation with respect to habitat selection in a macropodid community comprising the western grey kangaroo Macropus fuliginosus, red-necked wallaby M. rufogriseus and swamp wallaby Wallabia bicolor in the Grampians National Park, Victoria, Australia. We used radio tracking to quantify habitat selection. We predicted that because the fitness benefits of generalisation and specialisation differ, there would be a mix of generalised and specialised species in our community. As all three macropodid species show marked sexual dimorphism, we also expected that they would show sex-based specialisation. Finally, because many large herbivores select different habitats for foraging and resting, we predicted that our species would specialise on a subset of their overall selected habitat based on activity period (diurnal or nocturnal). All three species specialised on the available resources to some degree. Western grey kangaroos were specialists, at least during the active period. Niche data for the two wallaby species were harder to interpret so we could not determine their degree of specialisation. Within species, we found no evidence of sex-based specialisation. However, we found clear evidence of specialisation by activity period in western grey kangaroos and red-necked wallabies, but not in swamp wallabies. The strength of behavioural decisions made during the active period in influencing specialisation points to the likelihood that bottom-up processes regulate this community.
KeywordsSpecialist Generalist Sexual segregation Resource use Foraging
We thank Daryl Panther, Jemma Cripps and many volunteers for assistance with macropod capture, Michelle Wilson for general assistance, and Parks Victoria and the (former) Department of Sustainability and Environment for logistical support and the use of Victoria Valley Airbase. Funding came from an Australian Research Council Discovery Project 0664120 grant to GC and a Holsworth Wildlife Research Endowment Fund grant to SG. SG was supported by an Australian Postgraduate Award.
Author contribution statement
SG and GC conceived and designed the study. SG conducted the field work with assistance from GC. SG, JD and ME analysed the data. SG wrote the manuscript; other authors provided editorial advice.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
All applicable institutional and/or national guidelines for the care and use of animals were followed. This work was conducted under The University of Melbourne’s Faculty of Science, School of Land & Environment, and Optometry and Vision Sciences Animal Ethics Committee Project Number 0810628 and the Department of Sustainability and Environment Permit Numbers 10004582, 10005421 and 10006116.
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