Comparison of methods based on the nutritional requirements and availability of biomass to estimate carrying capacity for white tailed deer

Abstract

Due to the importance of the estimation of carrying capacity (K animals/ha) in white tailed deer, the objectives of this study were: 1) To compare the estimation of K with five methods, three of them based on nutrient availability (dry matter (DM), digestible energy (DE) and nitrogen (N)), one based on pressure of pasture and one based on the requirement of metabolizable energy (ME) based on the ecological metabolism of the deer, and; 2) To compare the K estimated when using the total biomass or vegetation groups consumed by the deer (grasses, herbs, shrubs and trees). The information about diet composition and biomass was collected at a hunting ranch in Aguascalientes, Mexico. The results were analyzed as a factorial arrangement (5 x 4), with the factors being the estimation method and the vegetal group factors. The estimated K (deer/ha) with total biomass was the highest (1.043), followed by grass (0.707) and herbs (0.325), whereas the estimates with trees and shrubs were the lowest ones (0.228 and 0.032 deer/ha). The K estimated, based in shrubs availability gives the value most similar to the population density than with the other methods, independently of selected method (DM, DE or N availability, pressure of pasture or ecological metabolism). It is concluded that carrying capacity should be estimated based on shrubs availability when considering the population density (0.02 - 0.04 deer/ha) as the appropriate indicator to evaluate the carrying capacity.