Beak color dynamically signals changes in fasting status and parasite loads in king penguins

Abstract

Dynamic ornamental signals that vary over minutes, hours or weeks can yield continuous information on individual condition (e.g., energy reserves or immune status), and may therefore be under strong social and/or sexual selection. In vertebrates, the coloration of the integument is often viewed as a dynamic ornament, which in birds can be apparent in the beak. King penguins (Aptenodytes patagonicus) are monomorphic seabirds that possess conspicuous yellow-orange (YO) and ultraviolet (UV) beak spots that are used by both males and females in mate choice. We studied the dynamicity of beak spot sexual traits, and to what extent they reflected changes in individual condition in fasting king penguins and in penguins treated with an anti-parasitic drug. We also describe the maturation of this colorful ornament during the yearly catastrophic moult. On a time-scale of days to weeks, beak spot coloration changed in response to fasting and experimental changes in parasite load. Beak spot UV brightness decreased over a 10-day fast in breeding birds. For birds caught during courtship and held in captivity YO chroma decreased after a 24-day fast. Birds that were treated with an antiparasitic solution showed an increase in UV coloration after parasite removal. Altogether, our results show that beak spot coloration is a dynamic ornament that reflects multiple dimensions of changes in individual condition in breeding-fasting penguins.

Sex‐specific lateralization during aggressive interactions in breeding king penguins

“…68–69 in Jouventin & Dobson, ). Our previous studies have shown that the color of right and left ornaments is similar (repeatable) (Schull et al, , ), and those ornaments thus likely convey similar information. Sex‐dependent lateralization may thus allow penguins pairs to benefit from not having to learn how to coordinate their behavior across multiple breeding seasons, as the direction of lateralization of successive mates should be similar.…”

Sex identification in King Penguins Aptenodytes patagonicus through morphological and acoustic cues

“…However, colour parameters of the beak in King Penguins have been shown to vary seasonally and depend on the fasting status and parasite load (Schull et al . ). Thus, such a dynamic signal might be inapt to encode individual or sex information.…”

Experimental stress during molt suggests the evolution of condition‐dependent and condition‐independent ornaments in the king penguin

“…Further, the color of yellow breast feathers (also containing the endogenously synthetized pterin pigment) has been related to innate immunity (Nolan, Dobson, Dresp, & Jouventin, ), suggesting that genes involved in the production of that specific pigment may also be linked to the immune system. There is also support for links between ornament colors and various condition indices, including body size and condition, stress status, and metabolic rate (Keddar, Couchoux, Jouventin, & Dobson, ; Schull et al., ; Viblanc et al., ) (see Table ). Finally, the beak spot ornament is a dynamic signal, reflecting short‐ to medium‐term physiological changes in parasite loads and fasting status (Schull et al., ).…”

“…There is also support for links between ornament colors and various condition indices, including body size and condition, stress status, and metabolic rate (Keddar, Couchoux, Jouventin, & Dobson, ; Schull et al., ; Viblanc et al., ) (see Table ). Finally, the beak spot ornament is a dynamic signal, reflecting short‐ to medium‐term physiological changes in parasite loads and fasting status (Schull et al., ). However, experimental studies are now required to test whether trait production (i.e., beak spot and auricular patch coloration and size) is condition‐dependent.…”

“…In the king penguin, both the entire plumage and the yellow–orange keratin beak plates are renewed each year during the molt, which occurs over a period of 3–4 weeks (Schull et al., ; see Figure ). This particular context of a complete renewal (i.e., production) of all ornaments over a short period of time provides an ideal opportunity to investigate the costs of production of ornaments used in sexual and social contexts, and thus to examine whether sexual and social ornaments differ in their costs of production.…”