Nest-site utilisation and niche overlap in two sympatric, cavity-nesting finches
James Brazill-Boast A B , Sarah R. Pryke A and Simon C. Griffith AA Department of Brain, Behaviour and Evolution, Macquarie University, Sydney, NSW 2109, Australia.
B Corresponding author. Email: james.brazill-boast@mq.edu.au
Emu 110(2) 170-177 https://doi.org/10.1071/MU09045
Submitted: 25 May 2009 Accepted: 22 March 2010 Published: 26 May 2010
Abstract
Determining the relative access of a species to critical limiting resources requires knowledge of the spectrum of their resource utilisation (niche space) and that of potential competitors, and the frequency distribution of resources in the environment. We used this theoretical framework to assess the relative access to nesting sites and the potential for interspecific competition between two sympatric cavity-nesting finches. Gouldian (Erythrura gouldiae) and Long-tailed (Poephila acuticauda) Finches are both estrildid finches with similar ecological requirements, gross morphology and geographical ranges. By measuring the characteristics of all tree-cavities in an area of breeding habitat, and identifying those used by each of the two species, we were able to quantify the relationship between total available variation and variation in use by Gouldian and Long-tailed Finches. Using a likelihood-based method, we found that Long-tailed Finches exhibited a broader niche than Gouldian Finches with respect to available variation, and that these niches overlapped. Using these data we estimated that the effective availability of suitable nesting sites for Long-tailed Finches was 38% greater than for Gouldian Finches. Their relatively specialised niche and overlap with a more generalist competitor has the potential to constrain reproduction for Gouldian Finches, and will have implications for the conservation of remaining populations of this endangered species.
Acknowledgements
We thank Liam Brunner, Josephine Dessmann, Christophe Dufresnes and Nina Svedin for all their help with data collection in the field; Save the Gouldian Fund (Cooranbong, NSW) for providing valuable equipment to the project; and the Shire and residents of Wyndham for their help and hospitality. Funding was provided by the Australian Research Council Discovery (S. R. Pryke) and Linkage Grants (S. R. Pryke and S. C. Griffith), and a Macquarie University Research Excellence Scholarship (J. Brazill-Boast).
Ackermann, M. , and Doebeli, M. (2004). Evolution of niche width and adaptive diversification. Evolution 58, 2599–2612.
| PubMed |
Colwell, R. K. , and Futuyma, D. J. (1971). On the measurement of niche breadth and overlap. Ecology 52(4), 567–576.
| Crossref | GoogleScholarGoogle Scholar |
Goldingay, R. L. (2009). Characteristics of tree hollows used by Australian birds and bats. Wildlife Research 36, 394–409.
| Crossref | GoogleScholarGoogle Scholar |
Hutchinson, G. E. (1959). Homage to Santa Rosalina or Why are there so many kinds of animals? American Naturalist 93, 145–159.
| Crossref | GoogleScholarGoogle Scholar |
Miller, R. S. (1967). Patterns and processes in competition. Advances in Ecological Research 4, 1–74.
| Crossref | GoogleScholarGoogle Scholar |
Nilsson, S. G. (1984). The evolution of nest-site selection among hole-nesting birds: the importance of nest predation and competition. Ornis Scandinavica 15, 167–175.
| Crossref | GoogleScholarGoogle Scholar |
Tidemann, S. C. (1996). Causes of decline of the Gouldian Finch Erythrura gouldiae. Bird Conservation International 6, 49–61.
| Crossref | GoogleScholarGoogle Scholar |
von Haartman, L. (1957). Adaptation in hole-nesting birds. Evolution 11, 339–347.
| Crossref | GoogleScholarGoogle Scholar |
Wilson, D. S. , and Yoshimura, J. (1994). On the coexistence of specialists and generalists. American Naturalist 144, 692–707.
| Crossref | GoogleScholarGoogle Scholar |
Woinarski, J. C. Z. , and Tidemann, S. C. (1992). Survivorship and some population parameters for the endangered Gouldian Finch Erythrura gouldiae and two other finch species at two sites in tropical northern Australia. Emu 92, 33–38.