Conservation of the threatened Strange-tailed Tyrant Alectrurus risora in the eastern Chaco: Nesting habitat and Reproductive success.

DI GIACOMO, ALEJANDRO G.; DI GIACOMO, ADRIÁN S.; REBOREDA, JUAN C.

Brasilia, Brasil

Congreso; XIX Annual Meeting of the Society for Conservation Biology; 2005

Society for Conservation Biology

We studied the reproductive success of globally threatened Strange-tailed Tyrant Alectrurus risora in the eastern Chaco. The study was conducted at Reserva Ecológica El Bagual, Formosa, Argentina (26° 11´ S; 58° 57´ W). At the beginning of the breeding season, a small fraction of the male population established adjacent breeding territories, where they displayed for attracting females that nested clumped in male territories. Males provided no resources for females and they did not participate in any form of parental care. Nests were built in two main habitats: 1) grasslands dominated by Imperata brasiliensis or Andropogon lateralis (uplands), and 2) grasslands dominated by Paspalum intermedium (lowlands). More than 90% of the area suitable for nesting was lowland, but only 18% (29/162) of the nests were built in this habitat. Nesting success, and hatchability and chick survival in successful nests did not differ between habitats, but males had more nests per territory in upla nds than in lowlands. Our results indicate that Strange-tailed Tyrants prefer upland habitats for nesting and that this preference is associated to a higher reproductive success of males but not females. The provision of appropriate grassland habitats could be a management option for Strange-tailed Tyrant populations in eastern Chaco.