Nesting behavior of male and female Undulated Antshrikes (Frederickena unduliger)

Undulated Antshrikes (Frederickena unduliger) inhabit dense lowland humid forest understory and, as with other species of antbirds, many aspects of their behavior and ecology are poorly known, especially their breeding biology. We provide the first detailed information about their breeding biology based on three nests monitored in the buffer zone of the Manu National Park, Madre de Dios, Peru, from August to December in 2012 and 2013. Nests (N = 3) were large cups woven to the crossing of two horizontal branches. Eggs were white with purplish hairlines and spots, and all three clutches consisted of two eggs. Both males and females incubated eggs and fed nestlings, but only females incubated eggs at night. Provisioning rates and time spent brooding nestlings did not differ between the sexes. Most aspects of the nesting behavior of Undulated Antshrikes in our study were similar to those reported for other species of antbirds, including placement and composition of nests, clutch size, and provisioning rate. However, incubating behavior and the duration of the nestling period of antbirds appear to be influenced by body mass, with larger species such as Undulated Antshrikes having greater nest attentiveness and longer nestling periods than smaller species. Additional studies of other species of antbirds are needed to better understand factors that might contribute to similarities and differences in the nesting behavior of thamnophilids.