Sexual selection and the function of a melanin-based plumage ornament in polygamous penduline tits Remiz pendulinus

Abstract

Melanin-based ornaments are often involved in signaling aggression and dominance, and their role in sexual selection is increasingly recognized. We investigated the functions of a melanin-based plumage ornament (facial 'mask') in male Eurasian penduline tits Remiz pendulinus in the contexts of male-male aggression, mating success, and parental care. The penduline tit is a passerine bird with a unique mating system in which both sexes may mate with several mates in a breeding season, and one (or both) parent deserts the clutch. Our study revealed that mask size of males is more likely an honest signal used by females in their mate choice decisions than a trait involved in malemale competition. First, mask size increased with both age and body condition, indicating that the mask may signal male quality. Second, males with larger masks paired more quickly and had more mates over the breeding season than males with smaller masks. Third, we found no evidence that male mask size signals male-male aggression or dominance during competitive encounters. The increased mating success of large-masked males, however, did not translate into higher reproductive success, as nestling survival decreased with mask size. Therefore, we conclude that there is either no directional selection on male mask size or males with larger masks receive indirect, long-term benefits.

The expression of melanin-based plumage is separately modulated by exogenous oxidative stress and a melanocortin

“…Hoi & Griggio 2008;Kingma et al 2008;McGraw 2008;Galván & Møller 2009). The honesty of these signals would be mediated by the relative cost that signallers experience during the trait production or during its maintenance (Hasson 1997;Alonso-Alvarez et al 2009).…”

Individual variation and the resolution of conflict over parental care in penduline tits

“…Males with larger masks are more attractive [38] and more likely to desert [39], whereas the female's decision to care or desert does not appear to be influenced by the size of her partner's mask [39]. We therefore assumed that all males with a larger-than-average mask (i.e.…”

“…By incorporating individual variation, we can account better for population-level patterns of parental care. Finally, we incorporate an individual plumage trait, male 'mask' size, which may be associated with such individual variation in payoffs as it predicts the likelihood for males to desert the clutch [38,39]. This further improves the predicted population-level patterns of care.…”

Breeding system and cuckoldry in the Eurasian penduline tit (Remiz pendulinus)

“…Ten days old chicks were handles similarly, although they were ringed only with one metal ring, since the returning rate to the same area is very low in this species (Kiss and Szentirmai 2009). For a more detailed description of the field methods and how we took the photos see Kingma et al 2008 and our Field Protocol at http://www.bath.ac.uk/bio-sci/biodiversity-lab/pdfs/PT_%20Field%20Guide_1_2.pdf 193.…”

“…Once deserted the birds do not return to the nest, one nest is used for only one breeding attempt. More attractive males (males with a bigger facial mask) are more likely to desert (van Dijk 2009) and the more attractive a male is the shorter the time period will be for him to find a mate (Kingma et al 2008).…”