Study to determine cougar impact on calf elk

Elk calves are being equipped with radio collars as part of a three-part elk and cougar study being conducted by the Oregon Department of Fish and Wildlife. Submitted photo

A three-part study on elk and cougar in the Sled Springs and Wenaha Units of Wallowa County is in its second year and environmental groups have already made their presence felt.

Eight environmental groups, including the Sierra Club and the U.S. Humane Society, have filed a suit regarding the study's possible conclusion to reduce the number of cougars in the prescribed units.

A federal district court judge has already ruled that an Environmental Assessment on the overall study is sufficient, but added that an Environmental Impact Statement (EIS) will be required before any cougar populations can be manipulated to protect elk herds.

Bruce Johnson of the Oregon Department of Fish and Wildlife (ODFW) office in La Grande says the study will last three years or five years, depending on whether the EIS is included. The EIS, which the environmentalists favor, will be mandatory if the study goes to five years. The project is funded 75 percent through the federal excise tax on guns and ammunition and a 25 percent state match.

The threefold aspects of the study are to monitor the nutritional condition of cow elk, learn about the survivability of calf elk and learn about cougar density in the two units. The calf survival rate in both units, but especially the Wenaha Unit, have gone down dramatically in recent years and one goal of the study is to determine the relationship between that trend and the numbers of predatory cougars in the area. A fourth segment of the study, one which has yet to begin, will be the determination of bear density in the two units.

Cougar populations have increased since the use of hounds was outlawed in 1994 for the hunting of the primarily nocturnal animal.

The study began in December of 2001. This is the second winter of the study during which ODFW personnel and two contracted houndsmen track and tree cougars. They are then tranquilized with a dart gun and lowered out of the tree. The age of the cougar is recorded, as is its weight. It is determined if the cougar is pregnant and a sample of tissue is taken for later DNA analysis. The cats are ear tagged and adults weighing 120 pounds or more are equipped with a radio collar. To date 29 cougars have been fitted with radio collars.

A helicopter was used to locate and tranquilize cow elk in the months of March and November, 2002. The calves were caught with a net gun or captured by hand.

The assessment of the cow elk's body condition is done with the help of an ultrasound machine to determine body fat and muscle thickness. Body condition scoring is also applied to determine muscle thickness in the pelvis and hip areas. By feeling through the hide in those areas the cow is rated on a scale from one to five for nutritional condition. The cow elk are not weighed, but a tape measure records the girth of the animal and weight is estimated.

Radio collars are placed on the calf elk. In the future, if the collar becomes immobilized for a period of four hours, ODFW personnel are quick to find the collar and determine the cause of death.

Johnson says it is too early in the study to make any conclusions about cougar predation on calf elk. Signs of cougar and bear kills have been witnessed, but the sample is yet too small to make any determinations.

Over the past year 20 radio collars from each unit have been fitted on cow elk. Johnson said the goal is to capture and radio collar 40 calves from each unit. During the first year 62 calves were fitted with collars.

The Sled Springs/Wenaha Unit elk/cougar study is not unique to northeast Oregon, said Johnson. A similar study is under way in the state of Idaho.

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