Hosts of avian brood parasites have evolved egg signatures with elevated information content.

Published

Journal Article

Hosts of brood-parasitic birds must distinguish their own eggs from parasitic mimics, or pay the cost of mistakenly raising a foreign chick. Egg discrimination is easier when different host females of the same species each lay visually distinctive eggs (egg 'signatures'), which helps to foil mimicry by parasites. Here, we ask whether brood parasitism is associated with lower levels of correlation between different egg traits in hosts, making individual host signatures more distinctive and informative. We used entropy as an index of the potential information content encoded by nine aspects of colour, pattern and luminance of eggs of different species in two African bird families (Cisticolidae parasitized by cuckoo finches Anomalospiza imberbis, and Ploceidae by diederik cuckoos Chrysococcyx caprius). Parasitized species showed consistently higher entropy in egg traits than did related, unparasitized species. Decomposing entropy into two variation components revealed that this was mainly driven by parasitized species having lower levels of correlation between different egg traits, rather than higher overall levels of variation in each individual egg trait. This suggests that irrespective of the constraints that might operate on individual egg traits, hosts can further improve their defensive 'signatures' by arranging suites of egg traits into unpredictable combinations.

Full Text

Duke Authors

Cited Authors

  • Caves, EM; Stevens, M; Iversen, ES; Spottiswoode, CN

Published Date

  • July 2015

Published In

Volume / Issue

  • 282 / 1810

PubMed ID

  • 26085586

Pubmed Central ID

  • 26085586

Electronic International Standard Serial Number (EISSN)

  • 1471-2954

International Standard Serial Number (ISSN)

  • 0962-8452

Digital Object Identifier (DOI)

  • 10.1098/rspb.2015.0598

Language

  • eng