Biomass of mammal carrion available to Turkey Vultures (Cathartes aura) and Black Vultures (Coragyps atratus) along a commuter railway in New York, USA

Abstract

With 227,000 km of railways in the United States, wildlife-train collisions are more common than generally recognized and could be an  important carrion source for Black Vultures (Coragyps atratus) and Turkey Vultures (Cathartes aura). We conducted a five-year study  (2018-2022) in Dutchess and Putnam Counties, New York, USA to 1) estimate the biomass of mammal carrion available to vultures along  32.6 km of commuter railway, and 2) determine if vultures utilize train-killed wildlife as a food resource. During our study we recorded  154 individual mammals of 12 species killed by commuter trains. The number of train-killed mammals averaged 30.8/yr (SD ±13.1  mammals/yr), but varied widely, ranging from 13 to 45 individuals/yr. White-tailed Deer (Odocoileus virginianus) contributed the most to  this total, followed by Raccoon (Procyon lotor), Virginia Opossum (Didelphis virginiana), and Coyote (Canis latrans). We estimated that  6722.0 kg of mammal carrion resulted from train-wildlife collisions during our five-year study, and of this total, 4778.3 kg were potentially  available for consumption by vultures. We estimated that 29.3 kg of mammal carrion per km of railway was available for consumption by  vultures each year. During our five-year study, we found evidence that vultures fed on >90% of the train-killed mammal carcasses. Our  results suggest the commuter railway is attractive to foraging vultures because 1) carrion occurs at high concentrations relative to the  adjacent “natural habitat”, 2) the massive traumatic injuries associated with train-wildlife collisions facilitate utilization of carrion, and 3)  disturbance is minimal owing to the infrequent passage of trains (ca. 1 train/hr). Given that train-killed birds, frogs, snakes, and turtles  were not included in our analysis, the total biomass of carrion available to foraging vultures along the commuter railway may be  considerably greater than we estimated in this study.