Prey Hair and Bone Recovery in Ermine Scats

Abstract

We examined the relationship of hair (y,) and bone (Y2) weight to body weight (x) in meadow voles (Microtus pennsylvanicus). The regressions were linear in both cases: y, = 0.1541 + 0.0195x (r2 = 0.84), Y2 = 0.3776 + 0.0402x (r2 = 0.89). These equations were used to estimate hair and bone consumed when ermine (Mustela erminea) were fed meadow voles. Apparent digestibilities of these components were -5 and 60%, respectively, and did not differ (P < 0.05) between male and female ermine. These values are substantially lower than those previously reported for hair and bone digestibility in other predators. Such variability must be explained if scat analysis data is to be used to reconstruct diets in carnivores. J. WILDL. MANAGE. 52(4):657-660 Scat analysis techniques, used to determine the diet of carnivores, rely on identifying and quantitating undigested components of prey (e.g., hair and bone) appearing in feces. Estimating how many prey items of a particular species are represented by a collection of fecal fragments is difficult (Putman 1984). Selective consumption of prey parts (e.g., hair and skeleton) and differential digestion of these components may induce errors in the estimation of prey consumed. Several workers have attempted to account for these sources of error by developing correction factors relating fecal composition to prey consumed for specific predators and prey items (Lockie 1959, Frank 1979, Liberg 1982). Others(MeriwetherandJohnson 1980, Johnson and Aldred 1982) have measured the digestibility of carcass hair and bone as it differs among prey and predator species. Substantial disappearance of hair and bone has been reported during controlled recovery trials with prey species fed to coyotes (Canis latrans) (Meriwether and Johnson 1980) and bobcats (Felis rufus) (Johnson and Aldred 1982). However, different and sometimes unclear methodologies make comparisons among these experiments difficult. From our gross observation of ermine scats we could not agree that ingested hair and bone were destroyed to the extent reported by Meriwether and Johnson (1980) and Johnson and Aldred (1982). Our study was designed to quantify digestibility of hair and bone when ermine were fed meadow voles and to investigate reasons for the variability of previous digestibility