Date of Award
Doctor of Philosophy
A study of white-tailed deer (Odocoileus virginianus) fawn mortality and behaviors that influence success of the fawn's hider strategy was conducted in south-central Iowa, 1980-83, and a fawn capture method was developed that relies on monitoring movement patterns of radio-collared adult does during the parturition period. The fawn capture method was more efficient than previously used methods because it was less influenced by habitat and fawn density. Finite mortality rate of Iowa deer fawns was 27% at 180 days postpartum and nearly 75% of total mortality was the result of predation. Coyotes (Canis latrans) caused nearly 67% of the predator-induced fawn deaths and they killed fawns during all 30-day periods to 150 days. Causes of Iowa fawn mortality were similar to results from semiarid western regions, but mortality rates in Iowa were much reduced. Dam and fawn behavioral patterns corresponded with those expected to reduce fawn mortality from predation. Dams associated with their fawns for only about 20% of the day and minimized the length of contact periods with them during the first 6 weeks postpartum. The time of day when dams contacted their fawns and the length of time between successive contacts was unpredictable. When dams were not with their fawns during the first 4 weeks, the distance between dams and fawns was constant. Sibling-fawn distance relations and fawn movements were also adapted to minimize predation pressure. Fawn bedsite selection was not random. Bedsites were characterized by greater vertical and horizontal woody cover and less short- and medium-growing herbaceous cover than surrounding areas. Temperature influenced habitat density and slope direction at the bedsite, but did not influence the vertical and horizontal cover relationship between bedsites and the area surrounding bedsites. The difference between western and midwestern fawn mortality rates in most studies may be the result of differences in the effectiveness of dam and fawn behaviors to keep hidden the location of the fawn from predators that search visually.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
Craig Norman Huegel
Huegel, Craig Norman, "Predator-avoidance behaviors of white-tailed deer that favor fawn survival " (1985). Retrospective Theses and Dissertations. 7859.