FORAGE AND HABITAT LIMITATIONS FOR MOOSE IN THE ADIRONDACK PARK, NEW YORK

Abstract

We used browse availability models to estimate the number of reproductive female moose (Alces alces) that could be supported during summer and winter in the predominantly forested 23,000 km² Adirondack Park and Forest Preserve (Park) in northern New York State, USA. We developed allometric equations to predict available browse biomass for individual plants and subsequent biomass estimates in 6 major cover types to estimate the moose carrying capacity within the Park. Our model incorporated the differential availability and nutritional quality of woody browse species within each cover type and changes in local browsing intensity due to competing vegetation under two different foraging constraints – protein and digestible energy. We estimated the carrying capacity as 8 (protein constraint) and 135 × (energy constraint) greater in winter than summer. Spatially-explicit estimates of summer range capacity (Animal Use Days, AUD) based on the protein constraint correlated best with variation in local moose density derived from winter aerial surveys (R² = 0.75, P < 0.01, n = 18). Protein availability was limiting in summer (AUD = 457 moose) with sparse patches of regenerating forest (< 20 years old) on privately-managed lands estimated to support 86% more moose than the dominant matrix of wetlands and mature mixed-deciduous forest. The small and patchy moose population in the Park reflects the relative scarcity of regenerating forest and optimal foraging habitat. Given statutory constraints of timber harvest in the majority of the Park, active forest management on private inholdings will play an outsized role in managing the moose population.