Blunt egg pole holds cues for alien egg discrimination: experimental evidence

Eggshell colour patterns play a crucial role in avian host-parasite coevolution. In contrast to many experiments investigating general host egg discrimination abilities, studies testing where specific recognition cues are located on the eggshells (on blunt, sharp or both egg poles) are lacking. Prev...

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Bibliographic Details
Published in:Journal of avian biology 2010-03, Vol.41 (2), p.111-116
Main Authors: Polačiková, L., Grim, T.
Format: Article
Language:English
Subjects:
Acrocephalus arundinaceus
Animal nesting
Bird nesting
Birds
Brood parasitism
Eggs
Eggshells
Embryogenesis
Letter
Parasite hosts
Parasitism
Turdus philomelos
Warblers
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Summary:Eggshell colour patterns play a crucial role in avian host-parasite coevolution. In contrast to many experiments investigating general host egg discrimination abilities, studies testing where specific recognition cues are located on the eggshells (on blunt, sharp or both egg poles) are lacking. Previous studies suggested that discrimination cues might be located at the blunt egg pole, where the shell patterning is typically concentrated. We tested this hypothesis experimentally in species subject to interspecific (great reed warblers Acrocephalus arundinaceus, reed warblers A. scirpaceus), and also intraspecific parasitism (song thrushes Turdus philomelos, blackbirds T. merula). We examined host responses towards two types of intraspecific eggs painted non-mimetic immaculate blue either at blunt or sharp poles. All four species rejected eggs manipulated at the blunt pole at significantly higher rates, indicating that they perceive the critical recognition cues in the same egg part. Thus, the presence of egg recognition cues at the blunt egg pole may be a general phenomenon in birds parasitized by both intraspecific and interspecific parasites.
ISSN:0908-8857
1600-048X
DOI:10.1111/j.1600-048x.2010.04983.x