Melanic color-dependent antipredator behavior strategies in barn owl nestlings

Abstract

The arms race between predators and prey has led to morphological and behavioral adaptations. Different antipredator strategies can coexist within a population if each strategy is the result of a trade-off with competing demands. Antipredator behavior can be associated with morphological traits, like color patterns, either because in the context of sexual selection, coloration signals the ability to avoid predators or because coloration is a naturally selected trait useful in avoiding predators. Because in the barn owl (Tyto alba), heritable eumelanic plumage coloration is associated with the glucocorticoid-dependent response to stress, we tested whether antipredator behavior is also related to this trait. Compared with small-spotted nestlings, individuals displaying larger black spots hissed more intensely in the presence of humans, feigned death longer, had a lower breathing rate under stress, and were more docile when handled. Cross-fostering experiments showed that the covariation between the spot size and the duration of feigning death was inherited from the biological mother, whereas covariation between spot size and docility was inherited from the biological father. Our results confirm that melanin-based coloration is associated with suites of behavioral traits, which are under both genetic and environmental influence. Coloration can thus evolve as a direct or indirect response to predation, but it can also be a signal of antipredator strategies to potential mates.

Linking melanism to brain development: expression of a melanism-related gene in barn owl feather follicles covaries with sleep ontogeny

“…In contrast, in many other species, a suite of behavioral and physiological traits covary with the degree of melanism [5]. For example, in barn owls, the degree of eumelanin feather spotting covaries with anti-predator responses [6], natal dispersal [7], reproductive activity [8], parasite resistance [9], and the regulation of glucocorticoids [10] and energy [11]. The covariation between melanism and these traits suggests that the genes involved have multiple pleiotropic effects that extend well beyond pigmentation [12].…”

Melanin-based colour polymorphism signals aggressive personality in nest and territory defence in the tawny owl (Strix aluco)

“…Inherited variation in the deposition of melanin pigments (grey-black eumelanin and reddish brown pheomelanin) is frequently reported to covary with morphology, physiology, life history traits and behaviour such as resistance to stress, sexual activity and aggression (Roulin 2004;Ducrest et al 2008). Previous studies already reported associations between anti-predator behaviour and melanin-based colouration in a number of species including the common buzzard (Buteo buteo; Boerner and Kruger 2009), marsh harrier (Circus aeruginosus; Sternalski and Bretagnolle 2010), great tit (Parus major; Quesada and Senar 2007), barn owl (Tyto alba; Van den Brink et al 2012a) and European kestrel (Falco tinnunculus; Van den Brink et al 2012b). Melanin-based colouration can thus be associated with different levels of aggressiveness and be involved in specific trade-off resolutions such as investment in current and future reproduction.…”

Melanin‐Based Coloration in Juvenile Kestrels (Falco tinnunculus) Covaries with Anti‐Predatory Personality Traits

“…On the basis of the finding that eumelanism is associated with stress response, Van den Brink et al (2012) proposed the hypothesis that dark and light individuals may differ in their response to predation risk. Accordingly, these authors showed that when exposed to the threat of a potential predator, barn owl nestlings with larger eumelanic spots hissed more, were more docile, needed fewer attempts to induce death feigning [tonic immobility (TI) test] and breathed at a lower rate than those with smaller spots.…”