Effect of hair loss syndrome on survival, behavior and habitat selection of black-tailed deer fawns

Black-tailed deer (Odocoileus hemionus columbianus) of Washington State have existed with hair loss syndrome (HLS) since 1996. I looked at the effects of HLS on individual fawns by estimating survival rates, time budgets associated with feeding and scratching behaviors and important environmental characteristics at the microhabitat and microclimate scale. A total of 166 fawns were captured between 2006 and 2008. Survival did not differ between years resulting in an average annual survival rate of 0.37, with early survival (from estimated date of birth through nine weeks) of 0.71 and winter survival (1 Dec through 1 Mar) of 0.64. Survival rates were higher among non-hair-loss (NHLS) than HLS fawns. Predation was the primary, proximate source of mortality, with cougars (Puma concolor) being the most significant predator. Poor nutritional condition over the winter likely influenced mortality, given that 89% of fawns that died from predation also showed moderate to severe nutritional stress, based on examination of bone marrow. Fawns with HLS spent a greater proportion of time scratching and a reduced proportion of time feeding compared to NHLS fawns. The tradeoff between increased scratching and reduced feeding contributed to lower body condition indices and higher rates of nutritional stress in HLS fawns. Deer selected habitats with higher microclimate temperatures, greater canopy cover and lower mean shrub density iv compared to random sites. This supports the use of microhabitat and microclimate as a trade-off between forage quality and quantity, hiding cover from predators, and a need for increased thermal cover in the winter. I conclude that increased scratching among HLS fawns results in a reduction of time spent feeding, subsequently lowering body condition and over-winter survival.