Survival of fawns can be one the most important factors affecting deer population growth, but estimating survival is logistically challenging. Researchers capture and collar fawns soon after birth and try to monitor them for their first year using radio-telemtery.
Most sources of mortality occur early in life (e.g., predation, accidents, starvation, disease). Ideally, radio-collar designs should ensure animal welfare, minimize impacts on behavior, and maximize collar life. Expandable radio-collars are designed to stretch, expand at folds, deteriorate, and drop off of animals to accommodate growth. Multiple studies have reported premature loss or failure of fawn radio-collars.
Integration of GPS technology with expandable collar designs would help researchers to more efficiently assess survival. Also more information about the behavior of fawns could be collected including habitat use and their interactions with other deer and predators. However, the weight of batteries necessary to support GPS transmitters has limited their use with expandable collars. Most fawns weigh less than 8 pounds at birth. Additional modifications to expandable collars have been proposed and some have been deployed in the field. However, testing alternative designs of expandable collars for fawns in controlled settings like our captive deer research facility is warranted before extensive use in field studies with wild deer.
As part of his Masters research Zach Wesner is conducting this research project at the Whitehall Deer Research Facility. The project is funded by and in cooperation with Minnesota Department of Natural Resources.
Although radio collars with expandable designs have been used on fawns for years, the effects of heavier GPS collars on fawn behaviors have not been evaluated. If their movements are negatively affected by collar weight, fawns could be predisposed to risks like predation.
Zach Wesner takes numerous measurements of each fawn at birth and periodically during their first year of growth. In addition, he monitors collar fit and function, hair loss and examines each fawn for skin abrasions.
We are examining the effects of GPS collars on fawn behavior as they interact with their mothers, move about the paddock and even when they are relatively inactive.
At our captive deer research facility, we can obtain many hours of deer observations, which would be more difficult at a field site.