Foraging behavior, eco-morphology, and systematics of some antshrikes (Formicariidae, Thamnomanes)
Wilson Bulletin
1983
Journal Article
95
4
505-521
Reserva Nacional Tambopata animals birds animal behavior ecology taxonomy systematics Formicariidae Thamnophilus Dysithamnus Thamnomanes predation feeding Bolivia morphology large spatial scales Madre de Dios Bibliography
Most ant-eating birds (Formicariidae: Thamnophilus, Dysithamnus and similar) are generalist insectivores that feed by watching for their prey from perches. Many species of the South American genus Thamnomanes, however, are characterized by a prey-capturing strategy which appears to be unique in this family of birds. These Thamnomanes are insectivores that have specialized in the capture of prey in flight, using a strategy which combines long flights during which they feed with periods of lying in wait. Quantitative data is presented concerning certain aspects of this alimentary strategy in two species of Thamnomanes studied in Peru (Tambopata) and Bolivia (Beni). It is to be expected that the morphology of Thamnomanes will exhibit specializations reflecting this feeding behavior, i.e., that they will have longer wings, shorter tarsi and wider beaks than ant-eaters that feed from perches. These predictions are tested with the help of museum specimens; the morphology of Thamnomanes is shown to fit the predictions. The systematics of Thamnomanes is re-examined, especially the strategies for the capture of prey and the morphological specialization. It is recommended that four species be considered; these are known or deduced to be specialists in prey capture on the wing in flights of long duration, in the genus Thamnomanes. Morphological evidence regarding two species commonly classified as Thamnomanes: T. plumbeus and T. occidentalis, indicates that they are specialists in the capture of prey from perches, and they have been excluded from the genus.