The secretive forest-falcons of Amazonian Peru: Windows into their ecology.

摘要

Forest-falcons (Micrastur: Falconidae) include seven species of forest raptors found only in Neotropical rainforests. Forest-falcons are extremely shy and elusive, thus little is known about the natural history, distributions and abundances, and other ecological information about most members of this genus. Four to five species of forest-falcons coexist in some locations of the Amazonian rainforest, and an estimation of their species abundance and a description of their habitat affinities can provide valuable groundwork for understanding their interactions, as well as their habitat relationships. Detailed analysis of spatial movements by forest raptors can provide a more detailed portrait of potential differentiation of habitat use that could facilitate coexistence of many congeneric raptors in tropical forest.;For my study I focused on the Barred Forest-falcon (Micrastur ruficollis), Lined Forest-falcon (M. gilvicollis), Collared Forest-falcon (M. semitorquatus), Buckley's Forest-falcon (M. buckleyi) and Slaty-backed Forest-falcon (M. mirandollei) that occur in the lowland Amazonian rainforest of southeastern Peru. In Chapter 1, I present results of forest-falcon auditory surveys and calculated estimates of the species abundance and distributional patterns within the different habitats of the study site. M. ruficollis and M. gilvicollis were more frequently detected than the other three species and M. mirandollei the least. Forest-falcons were detected in all habitats of CICRA, but the species varied in their occupancy of those habitats. I estimated abundances for the three most commonly detected species of forest-falcons and found M. ruficollis to have the highest abundance, followed by M. gilvicollis, with M. semitorquatus much less abundant than the other two species.;In Chapter 2, I present results on radio-tracked forest-falcons from which I assessed detailed patterns of their habitat use and determined individual and species' home ranges and the degree of overlap within and between species in their home ranges. Average home range size estimates ranged from 186.8 ha for M. ruficollis and 192.27 ha for M. gilvicollis to 971.6 for M. mirandollei and 592 ha for M. buckleyi. Intraspecific home range overlap was low for both M. ruficollis and M. gilvicollis. Interspecific home range overlap was also low between M. ruficollis and M. gilvicollis, but much larger for each of these smaller species with M. buckleyi. Both M. ruficollis and M. gilvicollis used terra firme forest in higher proportion than any other habitat, but M. ruficollis used more palm swamp and less floodplain forest than M. gilvicollis . A single M. mirandollei individual used the terra firme forest in higher proportion than any other type of habitat, while an individual of M. buckleyi showed higher affinity for floodplain forest.;In Chapter 3, I present novel observations on the nesting biology of the poorly-known Buckley's Forest-falcon (M. buckleyi) over two consecutive nesting seasons. I described the nest, eggs and weekly morphological changes of the nestlings as well as provided information on food delivery and parental care.;Together, this work provides some of the first observations and robust population estimates for several species of forest-falcons, and provides essential background data for further ecological study of these important forest interior predators. As Amazonian habitats are destroyed, it becomes more important to gain insight into the habits and habitat use of these ecologically important denizens of some of the most biodiverse habitats on Earth.