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Elk Management
Proactive wildlife management practices of Theodore Roosevelt National Park (TRNP) are exemplified in the staff's efforts to monitor the health and vitality of its animal population. Elk have been the subject of extensive research and management during the past several years as the population has exceeded the park's target number of 360. Staff are continuously working to determine how an overabundant elk population will ultimately affect the park.
To address and reduce the increasing elk population within the park, roundups and translocation of live elk were conducted in 1993 and 2000. For these roundups, helicopters were used to direct animals to a handling facility, and corralled elk were then transferred off site to other federal entities, American Indian tribes and states for elk reintroduction programs in North Dakota, South Dakota and Kentucky.
Because the park was concerned about how an overabundance of elk might affect plant communities and other wildlife species, the staff initiated research in 1985 to provide insight into the ecology and population dynamics of elk in the South Unit.
In 1993, a model was developed for the allocation of forage resources to the four most numerous and wide-ranging ungulate species in TRNP: mule deer, bison, elk and feral horses. Park managers used this model to assist in managing ungulates to maintain a healthy native plant community, part of the overall health and well-being of the park.
Starting in 2000, the National Park Service (NPS) and U.S. Geological Survey (USGS) began studying the elk population at the park to learn more about the population, including its movements and diet.
Population Dynamics
A 2006 report documented the results of studies to estimate vital rates, including pregnancy rates, survival rates, age ratios and sex ratios in the elk herd at TRNP. A population projection model combined and compared these data to observe elk numbers and population ratios.
Elk Movement and Distribution
From 2003 to 2006, female elk older than 1 year-of-age were collared with Global Positioning Systems (GPS) to track their movement and distribution. Measurements were taken at 7-hour intervals so that 3 to 4 locations could be recorded per elk per day, distributing the sampling throughout the day and night. The results of the study provided insight into the seasonal movement of elk within and outside the park.
Comprehensive Diet Study
The park initiated a comprehensive diet study in 2003 of ungulates, which included bison, feral horses, elk, pronghorn, and mule and white-tailed deer. This study continues to examine the diets of a subset of the elk population (targeted collections outside the park using radio-collared elk) that seasonally migrate outside the South Unit of the park from April through November, and it describes and quantifies dietary overlap of managed ungulates, which are primarily elk, bison and feral horses. The data collected in this study may be used to update the forage-allocation model.
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