ABSTRACT
The endangered Peruvian Plantcutter (Phytotoma raimondii) is a strictly herbivorous, mostly folivorous passerine endemic to the arid lowlands of northwestern Peru. Previous information obtained from the study of 3 of its major populations consistently suggests the selective use of plant material from the shrub Grabowskia boerhaaviaefolia and Prosopis spp. trees; however, our generalized understanding about the relative importance of these plants could be biased. Some of the Peruvian Plantcutter's populations in which these plants are scarce, and even seemingly absent, have been generally overlooked. We investigated resource use for foraging and nesting by Peruvian Plantcutters at one of these locations. We conducted nest searches inside the area and diet selection analysis in 5 territories of mated pairs. We found 7 nests, built almost exclusively of Scutia spicata twigs, a shrub previously reported for another population as a selected food source along with G. boerhaaviaefolia and Prosopis spp. Here, S. spicata was the food source selected by all mating pairs while Prosopis pallida was scarce overall, selected by just one pair and found only within 2 territories. G. boerhaaviaefolia was not detected throughout the sampling area. This study reveals that the Peruvian Plantcutter occupies a wider range of breeding habitats than previously thought; however, its flexibility in resource use is still expressed within a narrow array of known selected plant species.