Measuring the functional responses of farmland birds: an example for a declining seed-feeding bunting
Article first published online: 6 JUN 2008
© 2008 The Authors. Journal compilation © 2008 British Ecological Society
Journal of Animal Ecology
Volume 77, Issue 4, pages 687–695, July 2008
How to Cite
Smart, S. L., Stillman, R. A. and Norris, K. J. (2008), Measuring the functional responses of farmland birds: an example for a declining seed-feeding bunting. Journal of Animal Ecology, 77: 687–695. doi: 10.1111/j.1365-2656.2008.01375.x
- Issue published online: 6 JUN 2008
- Article first published online: 6 JUN 2008
- Received 8 August 2007; accepted 18 December 2007Handling Editor: Tim Benton
- agricultural change;
- functional response;
- foraging behaviour
- 1Many farmland bird species have undergone significant declines. It is important to predict the effect of agricultural change on these birds and their response to conservation measures. This requirement could be met by mechanistic models that predict population size from the optimal foraging behaviour and fates of individuals within populations. A key component of these models is the functional response, the relationship between food and competitor density and feeding rate.
- 2This paper describes a method for measuring functional responses of farmland birds, and applies this method to a declining farmland bird, the corn bunting Miliaria calandra L. We derive five alternative models to predict the functional responses of farmland birds and parameterize these for corn bunting. We also assess the minimum sample sizes required to predict accurately the functional response.
- 3We show that the functional response of corn bunting can be predicted accurately from a few behavioural parameters (searching rate, handling time, vigilance time) that are straightforward to measure in the field. These parameters can be measured more quickly than the alternative of measuring the functional response directly.
- 4While corn bunting violated some of the assumptions of Holling's disk equation (model 1 in our study), it still provided the most accurate fit to the observed feeding rates while remaining the most statistically simple model tested. Our other models may be more applicable to other species, or corn bunting feeding in other locations.
- 5Although further tests are required, our study shows how functional responses can be predicted, simplifying the development of mechanistic models of farmland bird populations.