Exceptional variation in the appearance of Common Murre eggs reveals their potential as identity signals

• Main Authors: Montgomerie, Robert, Birkhead, Tim, Cox, Amelia, Thompson, Jamie
• Format: Other/Unknown Material
• Language: unknown
• Published: Zenodo 2022
• Subjects: Uria aalge; bird eggs; colour pattern; individual recognition; Common murre; Common guillemot; maculation; common guillemot; Common Murre; uria
• Online Access: https://doi.org/10.5061/dryad.0vt4b8h0f

We studied the ground colors and maculations of 161 Common Murre (Uria aalge) eggs laid by 43 females in 3 small breeding groups on the cliffs of Skomer Island, Wales, in 2016–2018. Both the colors and maculations varied much more among than within females, providing quantitative evidence for the egg traits that might facilitate the parents' ability to identify their own eggs on the crowded breeding ledges where the density is typically ~20 eggs m–2. Ground colors had a trimodal distribution of hue values (whitish to pale brown, pale blue, or vivid blue-green) and maculations ranged from none to complex squiggles and blotches. The eggs laid by each female in different years were similar to one another, and replacement eggs laid by females within years were also more similar to their first egg than to other eggs in the same breeding group. Egg appearance did not differ among the 3 breeding groups that we studied. Our findings thus support anecdotal observations that, within and between years, female Common Murres lay eggs that have similar ground colors and maculations. We do not, however, find evidence that there is much difference among the eggs laid in different parts of a colony. See README file. Funding provided by: Leverhulme Trust Crossref Funder Registry ID: http://dx.doi.org/10.13039/501100000275 Award Number: RPG-2015-221 Funding provided by: Natural Sciences and Engineering Research Council Crossref Funder Registry ID: http://dx.doi.org/10.13039/501100005049 Award Number: RGPIN/05711-2014