University of New Hampshire professor Peter Pekins, Ph.D., described a scene in New Hampshire’s North Country in spring 2013 that was disturbing.

Emaciated, dead moose calves were lying on bare ground. They were down to skin and bones, yet were still in good feeding habitat with no snow cover.

The dead calves were "literally sucked dry of blood" from parasitic ticks.

Pekins said the skin under their hair was either a mass of ticks or was crusted with blood where the ticks had fallen off.

"It’s very difficult to imagine until you see it," Pekins said.

Pekins is the head of the university’s Department of Natural Resources and the Environment. He heads the research effort that partners with the state to study the effects of tick infestation on the animals in the New Hampshire North Country.

"They bleed to death in a very short time frame," Pekins said. "The volume of blood loss … that’s what devastates the calf. It can’t manufacture enough blood quickly."

The situation brought together the university and the New Hampshire Fish and Game Department in a longterm study of moose habits and mortality in relation to both ticks and, by necessity, winter climate.

The study has grown this year to include data from moose in Maine and Vermont, but has roots that reach back several years.

In the early 2000s, there was anecdotal evidence based on reports by snowmobilers and sportsmen of tick infestations and dead animals. Researchers suspected the problem was cycling during other winter seasons in 2008 and 2011. The study began serious documentation in 2014.

Since New Hampshire was joined by Maine and Vermont, officials can "really get a handle on it," Pekins said, and the work has grown to its largest scope since inception.

Capturing moose

This winter, the department contracted with a Nevada-based helicopter capture company called Native Range Capture Services, which operates low-flying helicopters to swoop in over the animals it finds in the wild. Once discovered, the crew fired net guns and tranquilizer darts to corral the moose and subdue them.

Once the animals were temporarily immobilized, location collars were affixed, blood samples were taken and an initial tick count was conducted.

According to Kristine Rines, moose project leader, 13 adult cows and 37 calves were collared over a three-day period in northern New Hampshire this winter.

Ticks in winter

An average cow calf weighs 369 pounds. An average bull calf weighs 404 pounds. Counters found an average of 32 ticks on the then living calves and 15 ticks on the adult cows.

Weights were slightly lower in winter 2016, the first year researchers weighed the animals, but tick loads were higher. Adult cows carried an average of 44 ticks. Calves carried 67.

"If the number of ticks are down a little bit, it’s likely they’ll have a little less impact on the moose later this winter," said Kent Gustafson, wildlife programs administrator at Fish and Game.

"It isn’t so much the winter conditions this time of year. What’s more important is how soon the cold and snow come at the beginning of winter. That snow and cold tend to kill the ticks, so they quit getting on (the moose) in the fall.

"It’s also good to have snow lasting into spring," he continued. "The fully engorged female ticks will drop off in the spring. If when they drop off they land in snow, it can often kill them. If the ground is bare and dry, the ticks do really well.

"Ticks can quest far longer in the fall, often falling on bare ground in the spring, meaning more that following fall."

Yearlong research

The research isn’t over when the helicopter flies off. When the collared animals die, researchers act quickly to locate the dead moose and begin a new phase of study.

"If we can get to that moose and if it’s not frozen solid, the ticks stay on it," Pekins said.

Researchers will skin the moose and freeze the hide, and in the summer, students will perform a slow, comprehensive count of ticks.

The number can range from 35,000-95,000 on one single hide taken from a dead calf. Pekins says the mortality problem is primarily affecting calves, and that the hide tick counts are conservative because ticks may fall off.

Based on work the graduate students have done with weather data, Gustafson said winters have shortened by about two weeks over a period of 30-40 years.

"Winters have been getting slowly, but surely, shorter every year now to a point the ticks can have an advantage," Pekins said.

Don Himsel can be reached at 594-1249, dhimsel@nashuatelegraph.com or @Telegraph_DonH.