Is the conservation value of small urban remnants of eucalypt forest limited by increased levels of nest predation?
Scott D. Piper A B and Carla P. Catterall AA Faculty of Environmental Sciences, Griffith University, Nathan, Qld 4111, Australia.
B Corresponding author. Email: s.piper@griffith.edu.au
Emu 106(2) 119-125 https://doi.org/10.1071/MU05043
Submitted: 5 September 2005 Accepted: 28 February 2006 Published: 19 May 2006
Abstract
Levels of predation on bird nests may be increased in small remnant patches compared with levels in extensive forests, owing to edge-related nest predation or mesopredator release. Previous work using artificial nests has demonstrated that increased rates of nest predation, owing mainly to avian predators, occur near edges of fragmented subtropical Australian eucalypt forests. This implies that levels of nest predation within small patches of remnant forest, which could effectively be all ‘edge’, may also be increased. We used artificial nests, deployed on the ground and 1–4 m above the ground in shrubs, to compare levels of nest predation and predator assemblages between interiors of small (10–20 ha) suburban remnant patches and extensive tracts (>400 ha) of subtropical Australian eucalypt forest. Most predation of nests in shrubs in both remnants and extensive forests was by birds, although there were some differences in the assemblages involved. Ground-nests were far more likely to be depredated by mammals or lizards in the remnants than in the extensive forests. However, despite the differences between their predator assemblages, overall levels of nest predation did not differ significantly between remnants and extensive forests, suggesting that any edge-related predation was of insufficient spatial extent to affect the interiors (>50 m from external edges) of remnants in this size-class. Eucalypt forest remnants of 10–20 ha often support bird assemblages typical of extensive forest tracts, but may act as population sinks for these species if levels of nest predation are excessive. Our results support the contention, however, that remnants in this size-class are useful to the conservation of forest bird assemblages.
Acknowledgments
We thank the Brisbane City Council and the Queensland Department of Natural Resources, Mines and Energy for allowing us permission to work in forests under their management. We thank members of the Wildlife Ecology Discussion Group at Griffith University, and two anonymous reviewers, for their useful comments on earlier versions of the manuscript.
Barrett, G. W. , Ford, H. A. , and Recher, H. F. (1994). Conservation of woodland birds in a fragmented rural landscape. Pacific Conservation Biology 1, 245–256.
Catterall, C. P. , Kingston, M. B. , and Park, K. (1997). Use of remnant forest habitat by birds during winter in subtropical Australia: patterns and processes. Pacific Conservation Biology 3, 262–274.
Heske, E. J. , Robinson, S. K. , and Brawn, J. D. (2001). Nest predation and neotropical migrant songbirds: piecing together the fragments. Wildlife Society Bulletin 29, 52–61.
Mac Nally, R. , Bennett, A. F. , and Horrocks, G. (2000). Forecasting the impacts of habitat fragmentation. Evaluation of species-specific predictions of the impact of habitat fragmentation on birds in the box-ironbark forests of central Victoria, Australia. Biological Conservation 95, 7–29.
| Crossref | GoogleScholarGoogle Scholar |
Matthews, A. , Dickman, C. R. , and Major, R. E. (1999). The influence of fragment size and edge on nest predation in urban bushland. Ecography 22, 349–356.
Rogers, C. M. , and Caro, M. J. (1998). Song sparrows, top carnivores and nest predation: a test of the mesopredator release hypothesis. Oecologia 116, 227–233.
| Crossref | GoogleScholarGoogle Scholar |
Taylor, L. N. H. , and Ford, H. A. (1998). Predation of artificial nests in a fragmented landscape on the New England Tablelands of New South Wales. Wildlife Research 25, 587–594.
| Crossref | GoogleScholarGoogle Scholar |
Zanette, L. , and Jenkins, B. (2000). Nesting success and nest predators in forest fragments: a study using real and artificial nests. Auk 117, 445–454.