AVIAN VISION AND THE EVOLUTION OF EGG COLOR MIMICRY IN THE COMMON CUCKOO
Version of Record online: 19 MAR 2011
© 2011 The Author(s). Evolution© 2011 The Society for the Study of Evolution.
Volume 65, Issue 7, pages 2004–2013, July 2011
How to Cite
Stoddard, M. C. and Stevens, M. (2011), AVIAN VISION AND THE EVOLUTION OF EGG COLOR MIMICRY IN THE COMMON CUCKOO. Evolution, 65: 2004–2013. doi: 10.1111/j.1558-5646.2011.01262.x
- Issue online: 5 JUL 2011
- Version of Record online: 19 MAR 2011
- Accepted manuscript online: 22 FEB 2011 02:44PM EST
- Received August 14, 2010, Accepted January 28, 2011
- Arms race;
- brood parasitism;
- bird color space;
- egg rejection;
Coevolutionary arms races are a potent force in evolution, and brood parasite–host dynamics provide classical examples. Different host-races of the common cuckoo, Cuculus canorus, lay eggs in the nests of other species, leaving all parental care to hosts. Cuckoo eggs often (but not always) appear to match remarkably the color and pattern of host eggs, thus reducing detection by hosts. However, most studies of egg mimicry focus on human assessments or reflectance spectra, which fail to account for avian vision. Here, we use discrimination and tetrachromatic color space modeling of bird vision to quantify egg background and spot color mimicry in the common cuckoo and 11 of its principal hosts, and we relate this to egg rejection by different hosts. Egg background color and luminance are strongly mimicked by most cuckoo host-races, and mimicry is better when hosts show strong rejection. We introduce a novel measure of color mimicry—“color overlap”—and show that cuckoo and host background colors increasingly overlap in avian color space as hosts exhibit stronger rejection. Finally, cuckoos with better background color mimicry also have better pattern mimicry. Our findings reveal new information about egg mimicry that would be impossible to derive by the human eye.