Myrmeciza hemimelaena is a small species of formicarid, endemic to the Amazon, relatively common in the understory of dryland forests. Its distribution ranges from the Brazilian Amazon south of the Solimões and Amazon Rivers, east to the Xingu River, and south to northwestern Mato Grosso, eastern Peru, and northern Bolivia. Its geographic variation has not been quantitatively studied, however, three subspecies are recognized, M. h. hemimelaena, M. h. pallens, and M. h. spodiogastra. Despite its extensive distribution in the Amazon, very little is known about the biology of this species. During studies conducted since September 1997 in the Tapajós National Forest (in two blocks of 100 ha. where the wood was removed and in two blocks of 100 ha. demarcated in undisturbed areas, subdivided into quadrants of 50 x 50m), several pairs of the spider-tailed antbird, M. hemimelaenaena, were observed foraging on the antlers of trees fallen from natural clearings by treefall (Henriques, personal obs.). For this reason, we set out to determine whether M. hemimelaena is a specialist species in clearings and to make studies of morphometric and plumage geographic variation by studying specimens deposited at MPEG and LSUMNS, in a total of 87 males and 63 females. During the period 02 to 24 February and 20 April to 15 May intensive field studies were carried out in the Tapajós National Forest, where we captured 16 specimens in the understory, with 12/x captures in exploited areas and 4/y captures in non-exploited areas (x=970; y=717). Besides this data, we also have the vocalization of the bird recorded with the help of a SONY TCM 5000 recorder, coupled to a SANNHEISER ME-80 directional microphone. Despite the small number of captures, it is possible to confirm that M. hemimelaena is favored by clearings opened by selective logging, since the greatest number of captures occurred in the understory of an exploited area, but it is not yet possible to affirm that the species is a specialist in clearings.
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