Rarity in antpittas: territory size and population density of five Grallaria spp. in a regenerating habitat mosaic in the Andes of Colombia

Abstract

Between 1995 and 2000, we made a comparative study of ranging patterns of individuals of five sympatric species of antpitta Grallaria spp. that differ in body size and extent of geographical range. Grallaria milleri is restricted to a small area in the central Andes of Colombia, G. rufocinerea is endemic to the Central Cordillera, and G. ruficapilla, G. nuchalis and G. squamigera are widely distributed in the tropical Andes. Using mist-nets, we captured and banded 76 individuals of the five species during the five year study period. We also radio-tracked six individuals for periods of 30-60 days, to obtain estimates of territory sizes. Recapture patterns revealed that antpittas exhibited high site fidelity, remaining in the same patch for documented periods of up to 34 months. However, some individuals were captured only once, and were probably transient through the area. Territory sizes estimated were 0.5-5.4 ha for G. milleri (n = 7), 1.4 and 1.5 ha for G. rufocinerea (n = 2), 1.9 ha for G. ruficapilla (n = 1), 9.3 ha for G. nuchalis (n = 1) and 2 and 4.5 ha for G. squamigera (n = 2). We compared these data with territory estimates of other Neotropical Formicariids. Our results indicated that antpittas had relatively small territories, and had population densities higher than assumed previously for these secretive birds of the forest understorey.