The foraging behavior of the Large-headed Flatbill, Ramphotrigon megacephalum and the Dusky-tailed Flatbill, Ramphotrigon fuscicauda (Aves: Tyrannidae)

ABSTRACT Southwestern Amazonia has great bird diversity which includes birds specialized in bamboo forests. In this region, bamboo is considered a key element of the landscape. The objective of this study was to investigate and describe the foraging behavior of the Large-headed Flatbill, Ramphotrigon megacephalum (Swainson, 1835) and the Dusky-tailed Flatbill, Ramphotrigon fuscicauda Chapman, 1925, which occur sympatrically in the region and are considered bamboo specialists. This study was conducted between November 2013 and September 2014, within two fragments in the eastern portion of the state of Acre: Fazenda Experimental Catuaba, in the municipality of Senador Guiomard; and Reserva Florestal Humaitá, in Porto Acre. A total of 109 and 97 foraging events were registered, for the Large-headed Flatbill and the Dusky-tailed Flatbill, respectively. The two species frequently used bamboos for searching and capturing their prey. However, the large-headed Flatbill was more specialized in bamboo substrates. Both species use similar foraging techniques and the differences found between the two are minor, but when taken together, these differences may explain their ability to co-exist.