ABSTRACT We report the first record of Bronzed Cowbird ( Molothrus aeneus ) brood parasitism on a sedentary tropical population of the Blue-gray Gnatcatcher ( Polioptila caerulea ), which probably represents the subspecies P. c. deppei . Our observations represent the 46th known true host species parasitized by this cowbird species, the 104th host and victim, and the 3rd known brood parasite for the family Polioptilidae. “Victims” are all species parasitized by cowbirds and “hosts” are those species that hatch, feed, and successfully raise cowbirds. Our assignment of these records to the true host list are based on feeding behavior observations at a nest in Veracruz, Mexico. We provide additional information on nest characteristics of an understudied gnatcatcher population.

ABSTRACT Studying the anthropogenic components of landscapes can provide a solid groundwork to better understand ecological patterns and processes. In this study, we assessed bird species richness and composition in 5 different environmental conditions (well-preserved cloud forest, peri-urban forest, urban greenspace, shade coffee plantation, and cattle ranch) embedded in a landscape whose original vegetation was tropical montane cloud forest. Our results showed that the most similar vegetation structure and physiognomy were peri-urban forest and shade coffee plantation, with urban greenspaces comprising a highly different condition. Regarding species richness, we found no differences for the nonbreeding season (average values 32.9–41.8), but we did find statistical differences for the breeding season (average values 24.5–43.7); highest species richness was recorded for well-preserved cloud forest (43.7 calculated species), which was significantly different from shade coffee plantation (lowest species richness value 24.5) and urban greenspaces (29 calculated species). These results support the idea that during the nonbreeding season, when habitat requirements are less strict, species distribute homogeneously across the landscape, whereas species tend to be more selective and concentrated in original forests during the breeding season. Community composition during the breeding season showed a >40% similarity cluster composed of well-preserved cloud forest, shade coffee plantation, and cattle ranch. In the nonbreeding season, however, 2 clusters were formed at ∼30% similarity: (1) urban greenspaces and cattle ranch; and (2) peri-urban forest, shade coffee plantation, and well-preserved cloud forest. Our results highlight the overall negative effect of urbanization on breeding bird species richness and composition, as well as the importance of having large patches of well-preserved cloud forests in sheltering high bird diversity.