Comparative life history of cotingas in the northern Peruvian Amazon

Abstract: We investigate sociobiology of sympatric cotingas by comparing variation of common characters. The species studied (smallest to largest) are: Iodopleura isabellae, Porphyrolaema porphyrolaema, Cotinga maynana, C. cayana, Lipaugus vociferans, Phoenicircus nigricollis, Querula purpurata, Gymnodoerus foetidus and Cephalopterus ornatus. The relationship between size and sexual dimorphism was correlated, with mass and tail length being significant, and all other characters (total length, wing chord, sexual dichromatism and ornamentation) being non-significant. For mass and tail length, smaller species are characterized by females being larger than males, whereas females are smaller in the larger species. Although not significant with all species along the size gradient, sexual dichromatism is more extreme in certain smaller species (i.e., Porphyrolaema and Cotinga), and sexual ornamentation is present primarily in larger species. Dietary specialization increases with size, and most species exhibit low food resource defense intra- and interspecifically. Smaller species use higher parts of habitat structural attributes, whereas larger species use lower parts. Most of the smaller species are solitary, whereas larger species tend to travel in small flocks. Regarding courtship, smaller species are characterized by solitary male systems (including polygamy), with lekking in the medium species and/or monogamous courtship in the larger species. We offer three hypotheses (modified from Alcock’s model) as they relate to cotinga courtship strategy: 1) Solitary, dichromatic males of smaller species are attracted above the canopy because it highlights their iridescence and lures in females (cost = increased predation risk above the canopy, benefit = lower energy expenditure). 2) Actively courting males of medium species are attracted below the canopy to more aggregated fruit clumps; since bright coloring cannot be detected as well under the canopy, the males compensate through active courtship such as lek- king and/or vocalizing to lure in females (benefit = decreased predation risk below the canopy, cost = increased energy expenditure during courtship). 3) Males of larger species are lured to their courting sites by females that are attracted to the habitat containing the preferred resource; males typically court a single female using subtle ornamentation, as well as calling in some species.