Macedo_etal_AnimBehav

Males of these species are similarly coloured. Females of Myrmoderus loricatus bear more conspicuous dark plumage patches than females of M. squamosus. Males of these species are similarly coloured.

Males of Thamnophilus torquatus bear more conspicuous dark plumage patches than males of T. ruficapillus. Females of these species are similarly coloured.

Methods

Using playback experiments in the field, we assessed the strength of territorial responses by measuring number of songs, latency to approach and interaction time of females and males that were forming social pairs. Strong territorial responses correspond to higher values of these variables. We simulated territorial intrusions by a solitary female (female solo song), a solitary male (male solo song), and a social pair (duetting social pair).

Results: We found that females of Drymophila ochropyga and Mymoderus loricatus – which bear more conspicuous dark plumage patches – showed stronger territorial responses than females of D. genei and M. squamosus, respectively. Stronger responses occurred against simulated female and/or male intruders, but not against simulated social pairs. Males of Drymophila and Mymorderus species – which are similarly colored – showed similar territorial responses.

However, contrary to out predictions, males of Thamnophilus torquatus – which bear more conspicuous dark plumage patches – did not show stronger territorial responses than males of T. ruficapillus. Females of the Thamnophilus species – which are similarly colored – showed weak, similar territorial responses. Discussion: Our results suggest that eumelanic patches in antbirds may function as ornaments in intra- and intersexual contexts in females.

In contrast, in species pairs with greater interspecific differences in male ornamentation, territorial competition may occur predominantly among males and female mate choice may drive the evolution of male ornamentation.