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Interest in female ornamentation has burgeoned recently, and evidence suggests that carotenoid-based female coloration may function as a mate-choice signal. However, the possibility that females may signal status with coloration has been all but ignored. Bill coloration of female American goldfinches (Spinus tristis) changes seasonally, from dull gray in(More)
Many socially monogamous species paradoxically show signs of strong sexual selection, suggesting cryptic sources of sexual competition among males. Darwin argued that sexual selection could operate in monogamous systems if breeding sex ratios are biased or if some males attract highly fecund females. Alternatively, sexual selection might result from(More)
Since the dawn of abstract thinking, humans have wondered about the seemingly unnecessary elaborate orna-mentations of birds. Gaudy colours, cumbersome tails, complex vocalizations and bizarre displays are found in bird species from all corners of the globe. Darwin (1871) provided an elegant explanation for the existence of these non-utilitarian traits:(More)
Ornamental bill color is postulated to function as a condition-dependent signal of individual quality in a variety of taxonomically distant bird families. Most red, orange, and yellow bill colors are derived from carotenoid pigments, and carotenoid deposition in ornamentation may trade off with their use as immunostimulants and antioxidants or with other(More)
A Au us st tr ra al li ia an n J Jo ou ur rn na al l o of f Z Zo oo ol lo og gy y A journal for the publication of the results of original scientific research in all branches of zoology, except the taxonomy of invertebrates Abstract The white-winged fairy-wren (Malurus leucopterus) exhibits striking plumage colour variation between the Australian mainland(More)
Conspicuous ornamentation has been linked to immunological and physiological condition in males of many species. In species where both sexes are ornamented, it is unclear whether the signal content of ornaments differs between males and females. We examined the immunological and physiological correlates of carotenoid-based bill and plumage ornamentation in(More)
In habitats in which multiple species are prey to the same predators, individuals can greatly benefit from recognizing information regarding predators that is provided by other species. Past studies have demonstrated that various mammals respond to familiar heterospecific alarm calls, but whether acoustic similarity to a familiar call can prompt a mammal's(More)
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Status signals are linked to fi ghting ability and enable competitors to gain access to resources without risking injury in aggressive combat. Th e relationship between testosterone (T), a hormone that mediates aggression, and signals of status is well studied in males, but little is known about the relationship between T and female signals of status.(More)
Male and female American goldfinches (Spinus tristis) express condition-dependent carotenoid-based plumage and bill coloration. Plumage color is relatively static, as pigments incorporated into feathers during the spring molt cannot be mobilized thereafter. In contrast, bill color is dynamic, reflecting changes in condition over short time periods. Previous(More)