Ultraviolet crown colouration affects contest outcomes among male blue tits, but only in the absence of prior encounters

Abstract

Summary1. Static animal colour patches may function among competitors to minimize conflict escalation over resources, by serving as a signal of resource holding potential or aggressiveness. Empirical evidence for the use of colour patches in conflict resolution is largely restricted to pigment-based colours (melanins and carotenoids) and rarely defines the context in which the signals are used. 2. Here we test whether structural-based ultraviolet (UV) crown colouration functions in conflict resolution among dyads of first-year male blue tits Cyanistes caeruleus in captivity, in a context that is known to favour aggressive individuals. 3. We found that on first encounter in a pairwise context, experimentally UV-reduced males were significantly more likely to lose to control-treated opponents than expected by chance. However, this disparity was less pronounced when conflicts were settled with physical fighting or when the opponent was considerably smaller in size. 4. When the same dyads were tested again several weeks later, but with the UV treatment reversed among opponents, none of the effects remained significant, but instead the winner was most likely to be the individual that won at their first encounter. 5. Our results suggest that structural-based UV colouration can affect the outcome of an interaction, but that size differences and the outcome of initial interactions between opponents can override the influence of this signal in conflict resolution. Whether there is a functional basis to maintain a link between aggressiveness and colouration may thus be highly dependent on the general context under which individuals compete in the wild.

UV coloration influences spatial dominance but not agonistic behaviors in male wall lizards

“…In line with predictions of the badge of status hypothesis (Rohwer 1975;Maynard Smith and Harper 2003), UV reflectance influences either aggressive behaviors of male rivals or the outcome of contest in blue tits, sticklebacks, damselfishes, and several species of lizards (Alonso-Alvarez et al 2004;Siebeck 2004;Stapley and Whiting 2006;Whiting et al 2006;Rick and Bakker 2008;Rémy et al 2010: Vedder et al 2010Bajer et al 2011; and see a review by Olsson et al 2013). Yet, in wall lizards, we found no difference in contest scores and agonistic behaviors between male rivals in relation to UV treatments.…”

“…However, the absence of significant effects of a reduced UV coloration on agonistic behaviors and contest outcomes is not entirely surprising because the badge of status hypothesis predicts that color patches are more influential during the first stages of conflict resolution, when individuals are not familiarized to each other. For example, Rémy et al (2010) and Vedder et al (2010) demonstrated effects of UV coloration on male-male interactions between unfamiliar individuals only. In our study, the behavioral profiles of males changed significantly after the first trial, suggesting that rivals quickly became familiar.…”

“…Yet, in blue tits Cyanistes caeruleus, the UV crown coloration influences contest outcomes and aggressive responses differently depending on the familiarity and degree of asymmetry between opponents (Alonso- Alvarez et al 2004;Rémy et al 2010;Vedder et al 2010). Furthermore, in this species, UV coloration determines contest outcomes during the breeding season when competition for mates is maximal (Alonso-Alvarez et al 2004) but is also important during the non-breeding season (Rémy et al 2010;Vedder et al 2010). In other species, it is still unclear whether UV coloration plays a different role during male-male interactions associated with competition for mates than during competition for food and space.…”

Ultraviolet wing signal affects territorial contest outcome in a sexually dimorphic damselfly

“…Several examples from vertebrates indicate that UV reflectance influences the escalation and duration of maleemale competition in the damselfish Pomacentrus amboinensis (Siebeck, 2004), threespine stickleback, Gasterosteus aculeatus (Rick & Bakker, 2008), Augrabies flat lizard, Platysaurus broadleyi (Stapley & Whiting, 2006;, blue tit, Cyanistes caeruleus (Remy, Gregoire, Perret, & Doutrelant, 2010), and eastern bluebird, Sialia sialis (Siefferman & Hill, 2005). Yet only a handful of studies have shown that UV reflectance affects the outcome of maleemale competition in vertebrates, including the European green lizard Lacerta viridis (Bajer, Molnar, Torok, & Herczeg, 2011) and blue tit (Vedder, Schut, Magrath, & Komdeur, 2010), and few studies have been conducted in field populations.…”

Mediating male–male interactions: the role of the UV blue crest coloration in blue tits

“…We conclude that, in blue tits, UV-blue crest coloration 34 affects both social and aggressive responses towards unfamiliar individuals, and thus 35 it has some properties of a badge of status. 36 potentially familiar individuals, whereas a second study (Vedder et al 2009) found 100 that UV coloration influenced pairwise contest outcomes between unfamiliar males. 101…”