Elk mortality rate spiked in 2017

Poor flying conditions and a lack of available pilots kept the Panhandle’s Idaho Department of Fish and Game biologists grounded late last winter when field scientists are usually in the air counting elk.

“It was the first year we didn’t do aerial counts since I don’t know how long,” said Laura Wolf, a big game biologist for the department.

Wolf and her colleagues, however, had a back-up plan for getting a handle on regional elk numbers.

The department has over the last few years collared 160 cow and calf elk to help determine mortality rates for several Panhandle units along the Coeur d’Alene and St. Joe River systems.

Death rates for collared calves in units 4, 6 and 7 near Avery, was 50 percent this year with malnutrition and predation being the most prevalent factors, according to IDFG. The 2017 mortality rate jumped compared to the 20 percent mortality logged over the two previous years.

Each January since 2015 the department collared 60, 6-month-old elk calves and monitored their movement through a satellite GPS system that sends updates to in-house computers.

When a calf doesn’t move for a while, it is usually dead. With each dead calf an email is sent to biologists and within four days team members are in the field to find the dead elk calf and conduct a necropsy, Wolf said.

During the winters of 2015 and 2016, 80 percent of the elk calves survived until the end of May. Mortality in the 20 percent was caused by mountain lions (14 percent), wolves (3 percent) and parasite and disease was determined as the cause of death in the remaining 3 percent of the cases.

This year, however, half of the calves died before the end of May, with 16 percent of the deaths caused by malnutrition, Wolf said. Another 16 percent were killed by mountain lions, 6 percent were killed by wolves. Parasites were determined to be the cause of death in 3 percent of the cases and the cause of death in the others is unknown, she said.

Despite what appeared to be a large, calf die-off last winter, Wolf said the department’s figures show that calf/cow ratios have been steadily improving in the three units.

Calf-to-cow ratios in Unit 4, which includes a large chunk of the Coeur d’Alene Mountains above and below I-90, increased from 25 calves per 100 cows in 2014, to 32 calves per 100 cows last year.

In Unit 6, which includes the St. Joe from St. Maries to Avery, calf-to-cow ratios went from 19 to 35 in the same period, and in Unit 7, from Avery east, the numbers increased from 13 to 33 between 2014 and 2016, according to figures provided by IDFG.

The last year that calf-to-cow ratios were gathered in Unit 9, the Panhandle’s most southeast unit, the department found 20 calves per 100 cows.

In its elk plan, the IDFG directs its wildlife managers to strive for a calf-to-cow ratio above 30 per 100.

“Overall, elk herds in the Joe are doing better than they were several years ago,” Wolf said. “Populations are likely increasing especially in Unit 6 and the southern portion of Unit 4.”