Continuing Blue Mountain elk study shows contrasting results

LEWISTON – Officials from the Washington Department of Fish and Wildlife have released results from the second year of a much-watched elk calf survival study in the Blue Mountains.

The findings contrast sharply with the first year of data. During 2021, only about 13% of more than 100 elk calves that were captured, fitted with tracking collars and then released ended up surviving. In the second year, survival jumped to 47%.

In both years, predation, at about 77%, was the leading cause of mortality, and cougars were responsible for the majority of the predation – about 58% in year one and about 71% in year two.

The study, which has one year remaining, is being followed closely by camps at the opposite ends of the state’s political spectrum as it relates to the management of fish and wildlife. On one side, local politicians and hunting groups want the agency to help elk in the Blue Mountains by putting more pressure on mountain lions. On the other, wildlife and animal rights advocacy groups, along with a portion of the Washington Fish and Wildlife Commission, are highly skeptical of predator hunting and the ability of predators to drive population declines.

The elk herd in the Blues has fallen on tough times. It is about 25% below the 5,500-animal objective set by the department. A harsh winter with poor survival in 2017 started the trouble, which was accentuated by lingering winter conditions late into 2019. Since 2017, the agency has documented low recruitment of elk from calves to adults across the heart of the Blues, and the herd has been determined to be “at risk.”

That designation prompted a two-pronged monitoring project. The agency is looking at annual recruitment, expressed as the ratio of elk calves per 100 cows and tallied by aerial surveys. It is also looking at how many calves are surviving and what is causing mortality.

To get at survival, agency biologists are fitting newborn calves with collars that emit a mortality signal if the device has not moved in five hours. They then rush to the site and attempt to determine the cause of death.

During the first year of the study, the recruitment and survival data aligned. The calf-to-cow ration ranged from 13% to 19% and the survival was 13.6%. In the second year, recruitment ranged from 7% to 19% but survival was estimated at 47.5%. A calf-to-cow ratio of 25% is needed for elk herds to remain stable.

“Overall, the available information – consistently low recruitment ratios and 1 of 2 years of poor estimated survival – indicates that the capacity for this population to grow to its objective level is hindered, albeit potentially highly variable,” the agency wrote in a summary.

That sets up 2023 as potentially key to providing a more complete picture of the herd, recruitment, calf survival and the most common cause of mortality.

Paul Wik, district wildlife biologist for the agency at Clarkston and head of the project, stressed the study is incomplete and scientific prudence cautions against drawing premature conclusions, especially those which may be used to base management options. But he said the discrepancy in survival could be because of stark differences in climatic conditions. During Year 1, the area suffered under a heat dome that saw temperatures spike well above 100 degrees a few weeks after most calves were born. That was accompanied by a drought and followed by large wildfires that altered the way elk typically use their habitat. Year two saw much more moderate temperatures and above-average summer precipitation.

Wik said it’s possible the conditions during the summer of 2021, the study’s first year, led to reduced pregnancy rates that fall and fewer calves being born in the spring of 2022. Even though the number of calves may have been down, the wetter and more moderate temperatures could have led to higher survival. However, Wik is careful to caution that the study does not include a look at cow pregnancy rates or their overall health. He also noted variability in calf survival is common.

Wik did say that during both years of the study, most of the mortality is happening early in the lives of calves and that over-winter survival has been good. During harsh winters, mortality often shows up quite late.

“We have not documented any predation or starvation events after November in the two years,” he said. “So, one thing to take from that, if there was a carrying capacity issue, you would expect carrying capacity to show itself through poor survival especially with young of the year, so we don’t think it’s a habitat-driven issue.”

Wik said results from the 2023 group of collared calves and the entire study will be available next summer.

“We need the third year of data,” he said.