Consumers that are not ‘ideal’ or ‘free’ can still approach the ideal free distribution using simple patch-leaving rules
Article first published online: 21 MAY 2009
© 2009 The Author. Journal compilation © 2009 British Ecological Society
Journal of Animal Ecology
Volume 78, Issue 5, pages 919–927, September 2009
How to Cite
Griffen, B. D. (2009), Consumers that are not ‘ideal’ or ‘free’ can still approach the ideal free distribution using simple patch-leaving rules. Journal of Animal Ecology, 78: 919–927. doi: 10.1111/j.1365-2656.2009.01571.x
- Issue published online: 29 JUL 2009
- Article first published online: 21 MAY 2009
- Received 2 August 2008; accepted 24 April 2009 Handling Editor: Simon Butler
- Carcinus maenas;
- decision rule;
- ideal free distribution;
- optimal foraging theory;
- predator interference
1. The ideal free distribution (IFD) has been widely used to determine whether consumers distribute themselves optimally. However, this theory is based on three assumptions that are clearly violated in many systems. The theory assumes that all individuals know the quality of each available site, are equally free to move between all sites, and have equal competitive abilities.
2. I examine the utility of this theory to predict the distribution of the invasive European green crab Carcinus maenas, a species that likely violates all of these assumptions. I demonstrate three main findings.
3. First, understanding how density-dependent interference and size alter individual foraging behaviour is important for understanding the density and biomass distribution of C. maenas in invaded habitats.
4. Second, once behavioural mechanisms of crab foraging are accurately included in the model, the IFD does a good job of predicting the distribution of C. maenas, even though C. maenas violates the theory’s fundamental assumptions.
5. Third, C. maenas’ distribution can be obtained using simple decision rules and reasonable movement patterns.