Biggest Elk and Mule Deer Study Underway

March 21, 2005
By George Pauley - Idaho Department of Fish and Game

This past winter, Idaho Department of Fish and Game (IDFG) initiated a large scale, statewide research effort to capture, radio-collar and monitor hundreds of mule deer and elk encompassing 18 big game management units across the state. Past big game research in Idaho and elsewhere was typically conducted on a smaller scale in only one or two areas.

With smaller scale research, we had the advantage of concentrating financial resources to obtain detailed and precise answers to management questions. However, the application of those findings to other areas was always questionable. The current effort is designed to encompass the range of conditions in Idaho so that findings will have statewide application.

In mid- February, we captured, sampled and radio-collared 30 adult mule deer does and 30 adult cow elk in each study unit including Unit 28, 36B, 36A, 50, 60A, 43, 39, and 32. Most animals were captured using a helicopter that herded the animals into drive nets where they became entangled enough that biologists and volunteers could restrain and process them. In April, we plan to capture additional animals in Unit 10, 12, 19A and 23. The information gained from these animals will guide research efforts in subsequent years.

Each animal was fitted with a radio-collar that has a unique transmission frequency. The transmitter is used to periodically locate the animal to determine movements and habitat use. Additionally, the transmitter is equipped with a mortality sensor that allows us to investigate the causes of death.

A variety of information is obtained from each study animal. Blood samples are obtained to evaluate serum parameters, nutrient levels and to determine pregnancy. Levels of body fat are determined to evaluate the relative condition of deer and elk across Idaho.

What can we expect from this work? The body condition data will provide a foundation for evaluating nutritional conditions across the state. The condition data already collected revealed significant variation in the body fat levels of deer and elk, sometimes varying dramatically across small areas. The condition levels will be compared to use of various habitats, land management practices, fire history and other factors to evaluate links between habitat conditions and nutrition.

The data obtained from radio-collared animals will also provide a profile of survival rates and cause specific death rates. That information will allow us to evaluate the relative importance of various direct mortality causes, such as hunting and predation. In addition, condition levels will be compared to pregnancy rates and survival rates among areas to evaluate the effects of nutrition and condition on survival and productivity.

What is next? Calves and fawns survive at different rates than adults and are affected differently by factors such as nutrition, predation, hunting and so on. To fully characterize the performance of entire populations, it will be necessary to sample younger deer and elk.

Beginning this spring, we will capture newborn fawns and calves on a subset of the study areas. In December and January, we will then capture and sample older fawns and calves. This work will provide data on birth weights and growth rates, which are sensitive indicators of nutrition. As with the adults, the radio-collared samples will reveal variation in survival rates across study areas and the importance of different mortality agents.

Fish and Game has never before attempted to capture and collar as many adult deer and elk. This research will provide a detailed profile of population performance levels of deer and elk across the range of conditions in Idaho. It will allow us to characterize and compare levels of nutrition, production, survival and mortality. The information will be used to measure and predict relationships between habitat and nutrition, nutrition and survival, and nutrition and pregnancy.

George Pauley is a Wildlife Research Biologist who has been working for IDFG since 1990.