Immunocompetence and condition‐dependent sexual advertisement in male house sparrows (Passer domesticus)

Abstract

Summary1. We tested the condition-dependent hypothesis of sexual advertisement in house sparrows (Passer domesticus). Male house sparrows have a bib of black feathers which serves as both a badge of social status and as a cue for female choice. We manipulated environmental conditions during the premoult period of juvenile house sparrows kept in outdoor aviaries. Birds were assigned to two treatments differing in the amount of dietary proteins, which are known to aect the expression of immune response in birds. We tested whether birds in the protein-rich group had better immune responses and developed larger bibs than birds reared on a protein-poor diet. We also checked whether immune response was a predictor of survival and parasite resistance. 2. Individuals with higher cellular immune response at capture had greater probability to survive during the 3 months of the experiment, and they had a higher probability to recover from infection with Haemoproteus sp. (a blood parasite). Conversely, birds with high immunoglobulin concentrations at capture had a higher probability of mortality. 3. Birds on the protein-rich diet had a higher cellular immune response compared to birds in the protein-poor treatment. Humoral immune response showed the opposite pattern, being higher for birds in the protein-poor treatment. We did not ®nd any eect of food quality on the development of the badge, assessed as the size of the trait and its colour properties. 4. In conclusion, our results support the view that immune defences are important for survival and parasite resistance in natural populations, and that they might be costly to produce. On the other hand, we did not ®nd support for the conditiondependent hypothesis of sexual advertisement, suggesting that the badge may not be a costly trait to produce. However, badge size could re¯ect other aspects of condition. The kind of pigments involved in colour signals may be the key factor determining the production costs of such traits.

A window on the past: male ornamental plumage reveals the quality of their early-life environment

“…Finally, and consistent with previous work suggesting melanin-based traits are largely free from nutritional influence [22,26,62], we detected no effect of our nestling feeding treatments on black breeding plumage. Nevertheless, after controlling for any dietary manipulation, we found that earlier-hatched males had darker black plumage by the breeding season than later-hatched males.…”

A trade-off between embryonic development rate and immune function of avian offspring is revealed by considering embryonic temperature

“…We used two common assays of immune function [5,11,12] that have been related to offspring survival and disease resistance (e.g. [13]). In particular, we measured the inflammatory response to injection of phytohaemagglutinin (PHA, Sigma L-8754) at a standardized developmental stage (the day nestling primary pin-feathers broke their sheaths) and averaged the response for each nest.…”

Badge Size and Arrival Time Predict Mating Success of Red-Breasted FlycatcherFicedula parvaMales

“…The characteristics of the spectralreflectance profile (using UV-VIS spectrophotometry) of feathers from the badges of some individuals (unpublished data) indicated melanin rather than carotenoid pigmentation in this species. The role of melanin-based ornaments is rather related to social interactions, aggressive behaviour, nest defense, hormones and immune response, and these are not condition-dependent traits (Gonzalez et al, 1999;McGraw and Hill, 2000;Buchanan et al, 2001;McGraw et al, 2002;Hill, 2005, Nakagawa et al, 2007b;Quesada and Senar, 2007, Ducrest et al, 2010, Klvanova et al, 2011. However, other papers have reported that melanin-based plumage can be honest indicators of condition, parental effort and mate quality, for example, in the eastern bluebird Sialia sialis (Siefferman and Hill, 2003), Kentucky warbler Oporornis formosus (Parker et al, 2003) and penduline tit Remiz pendulinus (Kingma et al, 2008).…”