A single species of plant predicts territory occupancy in a population of Peruvian Plantcutters

Abstract

Habitat selection assessments at multiple spatial scales provide a more complete understanding of the habitat requirements of a species, a matter that is especially useful for managing endangered wildlife. Studies of the diet and population distribution of threatened Peruvian Plantcutters (Phytotoma raimondii) suggest that the presence of Prosopis spp. trees, and the shrubs Grabowskia boerhaaviaefolia and Scutia spicata could explain the scattered distribution of their remnant subpopulations. However, our overall understanding of this remains unclear and incomplete because plantcutters are often absent in areas dominated by Prosopis spp., and other species of plants have largely been overlooked in distribution models. One way to address this issue is to also investigate spatial distribution patterns at finer scales within subpopulations. We modeled the probability of territory occupancy at one of their last strongholds, the P omac Forest Historical Sanctuary in Peru. Our predictors were defined by biotic interactions using data collected in 2015 and 2016, and previous studies of their diet. We found that Peruvian Plantcutters consumed the leaves, fruits, and flowers of at least nine species of plants, but only G. boerhaaviaefolia shrubs, and the trees Prosopis spp. and Colicodendron scabridum were used more than expected based on availability. We did not observe consumption of S. spicata, but this plant was rare. Territory occupancy was positively influenced only by the availability of G. boerhaaviaefolia, a plant used by Peruvian Plantcutters both as a source of food and nest material. Our results suggest that, despite their diverse diet, Peruvian Plantcutters can be particularly dependent on the availability of G. boerhaaviaefolia. Accordingly, this may explain why both co-occur in most subpopulations. Lastly, although we found that Prosopis spp. did not explain territory occupancy, previous research shows that it does explain their distribution on a broader scale (across subpopulations). This inconsistency across spatial scales suggests a potential key role of Prosopis spp. in guaranteeing dispersal between and connectivity among subpopulations.