Plumage Brightness of Prey Increases Predation Risk: An Among-Species Comparison

Abstract

The risk to passerine birds of predation by the Sparrowhawk (Accipiter nisus) was analyzed with respect to differences in plumage brightness, body mass, and density of prey species, while taking into account phylogenetic relatedness of species. Data were collected from published sources in five separate areas along a south–north geographical gradient in Finland and consisted of 2214 prey remains collected from Sparrowhawk nests. Prey plumage brightness was the most important factor determining vulnerability to predation. In adults, male brightness was more important than female brightness in explaining prey vulnerability. Prey abundance did not affect the relationship between predation vulnerability and plumage brightness, because both rare and common species with bright plumage suffered higher predation. Prey species with large body mass were more vulnerable to predation in northern Finland, suggesting that in northern harsh conditions, Sparrowhawks may prefer large prey in order to fulfill their daily energy requirements. Our analyses provide evidence that predation may impose viability costs on sexually selected traits such as plumage brightness and body size.

Plumage brightness, vigilance, escape potential, and predation risk in male and female Eurasian Siskins (Spinus spinus)

“…Conspicuous siskins adopted a vigilance and foraging strategy that reduced their predation risk compared with duller birds, supporting the view that they were at higher predation risk because they were easier to detect. This is in accordance with most studies' reports of a general relationship between plumage brightness and vulnerability to predation (Rytkönen et al 1998, Huhta et al 2003, Møller and Nielsen 2006. Our results also strongly support the ''compensation hypothesis'' recently formulated by Møller et al (2011), in that conspicuous birds would have evolved behavioral compensations to reduce their higher vulnerability to predation.…”

“…They found a generally positive relationship between plumage brightness and vulnerability to predation (Rytkönen et al 1998, Huhta et al 2003, Møller and Nielsen 2006. However, the results of these studies may be affected by the different behavior of conspicuous and nonconspicuous species.…”

Sex-dependent foraging effort and vigilance in coal-crested finches, Charitospiza eucosma (Aves: Emberizidae) during the breeding season: evidence of female-biased predation?

“…For instance, males of sexually dimorphic invertebrates, fish, and some birds seem to fall victims of predation more often than their female counterparts (MAGNHAGEN 1991, MCKELLAR et al 2009). These males may be more vulnerable because their behavior and morphological traits make them more conspicuous, contrasting with their cryptic or camouflaged females (conspicuity hypothesis: SLAGSVOLD et al 1995, HUHTA et al 2003. However, conflicting evidence showing that predation may be greater in females of some sexually dimorphic species do exist (KENWARD & MARCSTROM 1981, SARGEANT et al 1984, GOTMARK et al 1997, POST & GOTMARK 2006a.…”

Determinants of making success in female Tree Swallows (Tachycineta Bicolor)

“…There are three possibilities to explain why females manipulated to display bright, presumably high-quality, plumage ornamentation were less likely to retain their nest site than females with dull, low-quality plumage. First, lower nest site retention may have occurred if females in the enhanced plumage brightness treatment were depredated as a result of increasing the conspicuousness of their plumage (Huhta et al, 2003). Indeed, of the females that did not retain their nest site and breed after being manipulated, only two were observed breeding at my study area in subsequent years (Berzins and Dawson, unpublished data).…”