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We studied the diet of Crested Guans (Penelope purpurascens; Galliformes: Cracidae) in lowland tropical forest on Barro Colorado Island, Panama. From June-August 2015 we collected observations of foraging adults using five-minute focal follows of randomly chosen individuals. A total of 141 food items were recorded over 565 minutes of observations. Although Crested Guans are believed to be primarily frugivorous, we found that they consumed a high proportion of leaves (61.7% of items) and insects (24.8%), with fruits comprising a minority of items (13.5%). Guans preferred to eat young leaves, which are more tender and contain higher levels of nitrogen than mature leaves; however, young leaves also contain higher levels of tannins and other secondary defensive compounds, raising new questions about the mechanisms by which arboreal birds digest leaves. Recent studies have found similarly high levels of leaf consumption in other species of guans and chachalacas, suggesting that folivory may be more wi...

The Greater Ani (Crotophaga major) is the least well-known of the communally breeding crotophagine cuckoos, although it is locally abundant in Panama and northern South America. We present substantial new life history information from 87 breeding groups of Greater Anis at Gatun Lake, Panama, and the first description of their conspicuous, highly stereotyped communal displays. Breeding groups were composed of two to five socially monogamous pairs; no pairs nested singly. Seven groups also included an unpaired individual, which in three cases was confirmed to be a 1-year-old male from the previous year's nest. Groups of two and three pairs were most common (accounting for 75 and 20% of groups, respectively); groups containing more than three pairs were rare and their nests were abandoned before incubation began. Eggs were large (∼17% of adult body mass) and varied greatly in size (19–37 g). Egg and nestling development were exceptionally rapid: eggs were incubated for 11–12 days and nestlings were ...

Many species of trogons (Trogoniformes: Trogonidae) gather in mixed-gender calling assemblages during the breeding season. These assemblages have been compared to leks and are usually assumed to function in mate choice; however, no field data exist to support this hypothesis. I present five non-mutually exclusive hypotheses for the function of mixed-gender calling assemblages and test the predictions using field data from Black-headed Trogons (Trogon melanocephalus) in a lowland dry forest in Costa Rica. Adult trogons gathered in mobile assemblages of 3–12 individuals that called frequently and chased one another from perch to perch while moving through the forest. Groups formed at sunrise throughout all stages of the breeding cycle and were not significantly male-biased. Both breeding and non-breeding individuals participated in assemblages, and copulations were not observed in assemblages. Prey capture rates of individuals foraging in groups did not differ from those foraging alone. Males calle...

I studied the diet and foraging behavior of fledgling Black-crowned Night-Herons (Nycticorax nycticorax) in a mixed-species nesting colony of Black-crowned Night-Herons and Snowy Egrets (Egretta thula) in New Orleans, Louisiana. In 1 of 5 years, cannibalism of nestlings that had fallen or climbed out of nests was common, accounting for 66 of 94 (70.2%) prey items taken by fledglings. Juveniles took younger conspecifics by both predation and scavenging. Isolated incidents of cannibalism among Black-crowned Night-Herons have been reported previously, but not on a colony-wide scale.