Partitioning Forage Use among Wild and Domestic Ungulates in New Mexico

Abstract

Managing multispecies grazing on rangelands presents significant challenges, especially in distinguishing and balancing the specific forage utilization of wild and domestic species amid variable resource availability. Traditional grazing management primarily focuses on the quantity of animals in a pasture and the duration of their presence, yet assessing the intensity of grazing becomes complex when involving wild species like elk and feral horses. To improve our understanding and enhance grazing management practices, we deployed camera traps to observe cattle, elk, and horses within the critical habitat of the endangered New Mexico meadow jumping mouse (NMMJM). By applying animal use equivalents to these observations and comparing them with end-of-season utilization data, we gained detailed insights into species-specific forage use throughout the grazing season and across different life stages of the NMMJM. Additionally, we documented how cattle and elk abundance varied in response to season, fencing types, and presence of sympatric herbivore, with a particular focus on habitat use in relation to NMMJM critical habitat. Our findings indicate that cattle were more prevalent than elk, particularly near stream edges when accessible. Drier, resource limited conditions, further concentrated habitat use by cattle over the course of the grazing season and displaced elk into fenced portions of critical habitat. These dynamics underscore the complexity of managing grazing areas to support biodiversity, suggesting that adjustments in stocking rates, seasonal grazing schedules, and fencing maintenance are essential to mitigate the impacts of multispecies grazing and preserve critical habitats.