Carotenoid-based skin ornaments reflect foraging propensity in a seabird,Sula leucogaster

Abstract

Carotenoid-based ornaments are common signalling features in animals. It has long been proposed that such ornaments communicate information about foraging abilities to potential mates. However, evidence linking foraging with ornamentation is largely missing from unmanipulated, free-ranging populations. To investigate this relationship, we studied a coastal population of brown booby ( Sula leucogaster brewsteri ), a seabird with a carotenoid-based gular skin ornament. δ 13 C values from both feathers and blood plasma were negatively correlated with male gular colour, indicating birds that consumed more pelagic prey in offshore locations had more ornamented skin than those that fed on nearshore, benthic prey. This relationship was supported by our GPS tracking results, which revealed longer, more offshore foraging trips among highly ornamented males. Our data show that brown booby ornaments are honest indicators of foraging propensity; a link consistent with the rarity hypothesis and potentially driven by the concentration of carotenoids found in phytoplankton versus benthic algae. Carotenoid-based ornaments may reflect foraging tendencies in animals such as coastal predators that use food webs with distinct carotenoid profiles.

Range Expansion, Pairing Patterns, and Taxonomic Status of Brewster's Booby Sula leucogaster brewsteri

“…Montoya et al (2018) showed that the carotenoidbased greenish-blue color of the gular pouch of males was energetically expensive to maintain, that its chroma peaked during courtship, and that it may serve as a reliable signal of individual quality. Michael et al (2018) showed that color of the gular pouch in Brown Boobies in México was related to foraging range and location, with individuals in poor body condition constrained to low-cost, short-distance foraging trips closer to shore, where they were unable to obtain the pelagic diet necessary for production of the carotenoid-rich gular pouch ornament important in mate attraction. Cumulatively, this research indicates that the morphological differences between S. l. brewsteri and S. l. plotus act as an isolating mechanism that inhibits interbreeding.…”

Mate Choice, Sex Roles and Sexual Cognition in Vertebrates: Mate Choice Turns Cognition or Cognition Turns Mate Choice?

“…Impressive and well-studied examples comprise peacock spiders that use synchronous motion displays (Girard et al, 2011(Girard et al, , 2015 or bowerbirds and sage grouse, who adapt their courtship display intentionally in response to female signals (Patricelli et al, 2002(Patricelli et al, , 2006(Patricelli et al, , 2011Patricelli and Krakauer, 2010). Similarly, in carotenoid-dependent signaling systems such as siskins, brown boobies, house finches, or sticklebacks and guppies, superior foragers produce exaggerated sexual signals to impress courted females (e.g., Endler, 1980Endler, , 1984Kodric-Brown, 1985;Milinski and Bakker, 1990;Senar and Escobar, 2002;Karino et al, 2007;Mateos-Gonzalez et al, 2011;Michael et al, 2018). Therefore, in numerous taxa, males indicate their suitability as potential mates by various elaborate traits.…”