Long-term effects of early parasite exposure on song duration and singing strategy in great tits

Song is a sexually selected trait in many bird species and has been suggested to function as a signal of a male’s health and parasite resistance. Here we present an experimental field study on the long-term effects of parasite exposure early in life on adult bird song. We exposed nestling great tits (Parus major) to ectoparasitic hen fleas (Ceratophyllus gallinae) and on their recruitment into the local breeding population assessed the response to a playback of a challenging male in their breeding territory. We show, to our knowledge for the first time in a wild bird population, that parasite exposure early in life affects bird song: song duration of males that were exposed to parasites early in life was reduced by 32% compared with males that grew up in a flea-free environment. Early parasite exposure also significantly reduced the degree of song overlap with the playback, which has been shown to correlate with social status. There was no effect of early parasite exposure on the number of different song types sung or on the latency until the males started the vocal response to the playback. These results suggest that mates or rivals can use song duration and song overlap as proxies for an individual’s exposure to parasites early in life. It thereby highlights both the importance of parasites in maintaining honesty of sexually selected traits and the costs of parasitism in terms of reduced attractiveness and competitiveness. DOI: https://doi.org/10.1093/beheco/arp012 Posted at the Zurich Open Repository and Archive, University of Zurich ZORA URL: https://doi.org/10.5167/uzh-76104 Accepted Version Originally published at: Bischoff, Linda; Tschirren, Barbara; Richner, Heinz (2009). Long-term effects of early parasite exposure on song duration and singing strategy in great tits. Behavioural Ecology, 20:265-270. DOI: https://doi.org/10.1093/beheco/arp012 Longterm effects of parasite exposure early in life on song duration and singing 1 strategy – a case study in great tits 2 3 Linda L. Bischoff, Barbara Tschirren & Heinz Richner 4 5 Evolutionary Ecology Lab, Ecology and Evolution Institute, University of Bern, 6 Baltzerstrasse 6, 3012 Bern, Switzerland 7 8 Centre for the Integrative Study of Animal Behaviour, Macquarie University, Syd9 ney, NSW 2109, Australia 10 11 * author for correspondence: [email protected] 12 13 Short title: Parasites affect bird song 14 15