Behavioral Ecology Advance Access first published online on April 29, 2007
This version published online on May 2, 2007
Behavioral Ecology, doi:10.1093/beheco/arm027
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
State-dependent decision making: educated predators strategically trade off the costs and benefits of consuming aposematic prey
Centre for Behaviour and Evolution, Newcastle University, Henry Wellcome Building, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
Address correspondence to C. Barnett. E-mail: miriam_craig{at}xtra.co.nz.
 |
Abstract |
|---|
Aposematic prey advertise their defences, such as toxins or stings, to visually hunting predators using conspicuous warning coloration. Both the conspicuousness and the chemical content of prey determine the speed of avoidance learning by naive predators, and it has long been assumed that predator education is the main selective pressure in the evolution of aposematism. However, recent theoretical models have considered how educated predators could also exert significant selection pressures on aposematic prey by increasing their attack rates on defended prey in times of food shortage. Currently, there are no clear experimental data to support these models. In this study, we show that European starlings (Sturnus vulgaris) increase their attack rates on chemically defended insect larvae when their body masses and fat stores are experimentally reduced. In addition, the increase in attack rate is not simply due to indiscriminate attacks made when energy reserves are low but is based on knowledge about the prey's defences. Taken together, these results suggest that educated adult predators will strategically trade off the energetic benefits of prey against their toxic costs according to their energetic needs. This result challenges classic theoretical models of the evolution of aposematism based purely on predator learning and forgetting rates and demonstrates the need to consider energy-toxin trade-offs in foraging decisions on defended prey. We discuss the implication of these results for the evolution of chemical defences and warning signals.
Key words: aposematism, discrimination, energetic state, predation, quinine, receiver psychology.
Received 28 June 2006; revised 20 February 2007; accepted 27 February 2007.
CiteULike 
Connotea 
Del.icio.us What's this?
This article has been cited by other articles:
|
|
 |
|
  N.B Davies and J.A Welbergen Cuckoo-hawk mimicry? An experimental test Proc R Soc B, August 7, 2008; 275(1644): 1817 - 1822. [Abstract] [Full Text] [PDF]
|
|