Annual survival and cause-specific mortality of white-tailed deer fawns on Mount Desert Island, Maine

Long, Robert; Harrison, Daniel; O'Connell, Allan

FIELD WORK: 'White-tailed deer (Odocoileus virginianus) lack intrinsic mechanisms to maintain populations below K-carrying capacity. Thus, deer populations on a large island where most predators have been extirpated and hunting is prohibited should be limited by food resources. This is not the case on Mount Desert Island (MDI), Maine, where the deer population is stable or declining and is below forage carrying capacity. Studies elsewhere have suggested that low recruitment, associated with high mortality rates of fawns, may contribute to declines in deer populations. Thus, we monitored cause-specific mortality of fawns (n=29) from birth to 1 year of age during 1991-1995.' 'Annual rate of fawn survival was 0.26. Rate of predator-caused mortality was 0.52, with coyote (Canis latrans predation (n=8) accounting for at least 47% of mortalities from all causes (n=17). Mortality rate from drowning was 0.24 (n=3), and mortality rate associated with deaths from vehicles was 0.14 (n=3). An index to home-range area (MINDIST) was not different between a sample of fawns that died prior to 60 days of age (n=6) and fawns that survived (n=12). Of fawns radio-collared as neonates, 10 of 14 mortalities occurred during the first 2 months of life. Survival rate from 6 months to 1 year was 0.65; 4 mortalities (2 predation, 2 drowning) were observed during this interval. A subgroup of fawns (n=11) captured near the Sand Beach area had a higher rate of survival to 1 year of age (S=0.67) than did fawns from all other areas (n=18, S=0.00). Recruitment to 1 year of age was lower than has been observed in other northeastern deer populations. Low recruitment associated with multiple causes of fawn mortality may be limiting deer populations in some areas on MDI; however, different rates of fawn survival throughout MDI may explain an apparent patchy distribution of deer.' /STUDY LOCATIONS:/ /MOUNT DESERT ISLAND/Sand Beach/