Male spotless starlings adjust feeding effort based on egg spots revealing ectoparasite load

Publication Type:Journal Article
Year of Publication:2009
Authors:J. M. Aviles, Perez-Contreras, T., Navarro, C., Soler, J. J.
Journal:Animal Behaviour
Date Published:October
Type of Article:Article
ISBN Number:0003-3472
Accession Number:ZOOREC:ZOOR14602009277
Keywords:Carnidae, Carnus hemapterus, on Sturnus unicolor

Parents may vary their parental behaviour and investment in reproduction in response to parasiteinduced changes in the fitness prospects of their offspring. Thus, parents may use the physical condition of their offspring, or any other trait related to parasite load, to adjust parental effort. The immaculate eggs of the spotless starling, Sturnus unicolor, often become densely spotted owing to the activity of the ectoparasite carnid fly Carnus hemapterus. Spot density anticipates the intensity of fly infestation suffered by nestlings and, therefore, may serve as a cue for parents to adjust reproductive investment. By cleaning spots produced by C. hemapterus on eggs of spotless starlings, we manipulated the parasite's traces revealing its presence in broods of starlings, without modifying the level of infestation, to test whether parents use these signals to adjust reproductive effort. We found support for the hypothetical negative effect of Carnus flies since nestlings raised in nests with a higher fly load had lower body mass. The experimental egg cleaning during incubation did not change the intensity of carnid fly infestation during nestling development. However, it had a significant positive influence on paternal but not maternal effort. Our experimental results support the idea that spotless starling males adjust their effort in response to their perception of the fitness prospects of their nestlings as indirectly estimated by traces of parasites on the eggshells. As far as we know, this is the first evidence of the use of parasite traces to infer risk of parasitic infestation by animal hosts. [copyright] 2009 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

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