Jeff Koenings, Ph.D.
Director

Jerry Gutzwiler
Chairman
Washington Fish &
Wildlife Commission
 

Photo courtesy of USFS

Mountain goats are native to the Cascade Range in Washington state.

Scientists seek clues to mountain goat decline
Posted January 2004

"The bottom line is we just don't have a lot of research on goat biology in Washington," said WDFW wildlife biologist Cliff Rice, the study's leader. "We are basing a lot of our current knowledge on only a few observations and studies."

Rice and other biologists from WDFW, the U.S. Forest Service, National Park Service and the Sauk-Suiattle and Stillaguamish tribes are studying the mountain goat's health and seasonal habitat use. Last summer, the team examined and placed special transmitter collars on mountain goats throughout the Cascades, from the Mount Baker area near the U.S. Canadian border south to the Goats Rocks Wilderness area in Lewis County.

Using a gun that fired darts containing a safe, tranquilizing drug, biologists were able to briefly immobilize and capture 31 goats. Each animal was fitted with a global positioning system (GPS)-transmitting collar and given a thorough health exam.

The lack of historical mountain goat research is due likely to the rugged, remote habitat that the animals inhabit.

Biologists later fly over the capture sites to collect information transmitted from the collars. The flight data offers biologists baseline information on the animal's movement and habitat use.

"The weather can alter our plans, but we hope to fly once a week over areas where we tagged goats," Rice said. "Each collar transmits two different signals - one that serves as a beacon, so we can locate the animal, and one that we can then use to download GPS locations that show where the animal has been since the data was last downloaded."

WDFW biologist Cliff Rice measures the length of a sedated mountain goat's horns. This sub-adult female has already been fitted with a radio-transmitting collar. The hood over her eyes is in place to keep the animal calm and to protect her eyes during handling.

Each collar records the longitude and latitude of the animal every three hours. Biologists can pinpoint exactly where a mountain goat has been by plotting the GPS coordinates on a map.

"This data will help us create a formal habitat-usage map to identify all areas within the Cascades that are potential mountain goat habitat," Rice said. "Although we have a rough idea where mountain goats are during the summer, this data will give us much more detail about mountain goat movements during that time.

"On the other hand, for many of our mountain goats, we have virtually no idea where they are in the winter," he said. "There are few roads open to possible wintertime goat habitat areas, so access is difficult, at best."

Tracking the goats' movements and habitat requirements during the winter should add a new dimension to biologists' understanding of the animals' needs and how wildlife managers can ensure healthy populations.

The summertime goat-capturing effort gave biologists a rare opportunity to check on the health of individual animals. Rice said what the field checks didn't show about the goats' condition was surprising.

"We didn't encounter any emaciated animals, but we didn't encounter any fat ones, either," he said. "We were a little surprised during our September captures that we didn't find a single animal that was really piling on the fat like many animals tend to do just before winter.

"This year's dry summer could have hampered the goats' ability to put on fat before winter. It's also possible that mountain goats put on fat somewhere other than where we were looking. We know Indian tribes that hunted mountain goats used to render tallow from goat fat to provide lighting, so there must be fat sometime, somewhere on the animals.

A mountain goat ambles off after being fitted with a radio-transmitting collar. Data from the collar will give biologists a better understanding of the goats' habitat needs and uses.

"That's what makes this research project so important: Finding answers to some of these very basic life history questions that we have," he said.

There are a number of possible causes for the decline in goat numbers, including past overharvesting and illegal hunting, past timber harvest practices, predation, changes in habitat, or possibly a critical mineral deficiency that has been exacerbated by acid rain.

"Hunting is now only allowed on a permit basis, and there is no legal hunting at all in the areas where we have low goat populations," Rice said. "Past timber harvests of old-growth trees near cliffs and rocky outcroppings may have meant a loss of wintertime browse for the animals."

Hikers and mountain climbers can come into contact with mountain goats when the animals are on their summertime ranges, and Rice said that human presence could force the animals to move to areas with lower-quality food sources.

Biologists track collared goats (in circle) from an airplane fitted with a radio receiver (foreground).

Another possible reason for the decline in mountain goats could be a lack of an important trace mineral, selenium, in the plants goats eat.

Rice said biologists studying sheep populations in Montana and Colorado are working on a theory that acid rain -- caused by emissions from burning fossil fuels -- such as vehicle exhaust - changes plants' ability to absorb selenium from the soil. Washington's geologic makeup is already naturally deficient in selenium, so any dampening of a plant's ability to absorb the mineral could exacerbate the problem.

"That theory has not been proven, but there is circumstantial evidence that warrants a closer look," Rice said. "We will be considering all possible factors in trying to understand the decline in mountain goats that we've seen in some areas."

Another aspect of the mountain goat study is an effort to improve population survey methods for the animals, which are mainly done through helicopter flights.

"Survey results can vary considerably, which makes them difficult to interpret with any certainty," Rice said. "The data we collect from the collared goats will be used to refine our survey procedures to make them more effective, accurate and consistent."