Test of an adaptive hypothesis for egg speckling along an elevational gradient in a population of Mexican jays Aphelocoma ultramarina

Publication Type:Journal Article
Year of Publication:2009
Authors:Berg, EC, McCormack, JE, SMITH, THOMASB
Journal:Journal of Avian Biology
Date Published:2009
ISBN Number:1600-048X
Keywords:Aphelocoma, Aphelocoma sordida, Aphelocoma ultramarina, Aphelocoma wollweberi, Corvidae, Garrulus, Garrulus glandarius, Mexico
Abstract:The adaptive significance of avian egg speckling patterns has been a subject of ongoing debate. We examined speckling in a population of Mexican jays Aphelocoma ultramarina exhibiting extreme eggshell variability. We sampled 167 eggs at 55 nests from sites ranging across a steep elevation gradient within the Sierra del Carmen mountain range in Coahuila, Mexico, in order to test the recent hypothesis that egg speckling lends structural support to eggs and should therefore be more prevalent in females subject to reduced environmental calcium. Although we documented high variation in the amount and distribution of eggshell speckling within the Sierra del Carmen jays, we found no relationship between local soil calcium levels and the pattern of speckling. Our results indicate that explanations in addition to soil calcium levels are necessary to explain extreme variation in eggshell speckling in birds.
Short Title:Journal of Avian Biology
Scratchpads developed and conceived by (alphabetical): Ed Baker, Katherine Bouton Alice Heaton Dimitris Koureas, Laurence Livermore, Dave Roberts, Simon Rycroft, Ben Scott, Vince Smith