Counting ticks


The less-than-glamorous side of being a wildlife biologist

While being a wildlife biologist definitely has its exciting days — investigating wildlife mortalities like crime scene investigators or tracking wolves to determine how many are in a pack — other days can be more mundane, such as digging through bat guano or counting ticks. Yes, ticks — those tiny organisms that thrive on the blood of their prey like miniscule vampires. If they didn’t creep you out already, this might: ticks aren’t insects but members of the arachnid family, along with spiders and scorpions. While that’s enough reason for many of us to try to avoid them, that’s not an option for wildlife like deer and moose, which share habitat with ticks.

A collared moose in northeast Washington.

Moose are particularly vulnerable to these tiny critters, especially in early spring when their fat and energy reserves are lowest. It’s not uncommon, when working with moose, for biologists to find them covered in tens of thousands of ticks. This is called winter tick load. If you’ve spent much time in the woods, you may have seen the evidence of a moose experiencing it.

“We sometimes find moose beds on snowy roads, and you can see ravens hopping around the beds eating the ticks that came off when the moose moved on,” said Annemarie Prince, district biologist in northeast Washington.

A moose calf with fur loss, a sign of heavy tick load.

The ticks that impact moose (and also deer, elk, and bighorn sheep) are called winter ticks (Dermacentor albipictus) and are a different variety than those that humans can pick up. Winter ticks parasitize many species of wildlife with generally inconsequential effects, but moose suffer relatively greater tick loads with occasionally severe impacts. This is why biologists pay a lot more attention to ticks on moose and their potential impacts to populations than on other wildlife species.

Winter ticks feed off their host over multiple stages of life (larvae to nymphs to adults) from fall through winter. With a serious tick infestation — thousands of ticks, all taking blood meals — an individual moose experiences significant blood loss and has to increase time spent grooming, leading to serious energy deficits, loss of fur, and in some cases, death. Excessive grooming also means less time eating and watching out for danger, including predators and vehicles.

A WDFW wildlife veterinarian and two WDFW wildlife biologists collar a moose in February 2024.

Starting in winter 2024, Washington Department of Fish and Wildlife (WDFW) staff started a multi-year project to capture and collar female moose in northeast Washington’s Pend Oreille, Stevens, Ferry, and Spokane counties. This project will provide a lot of information about moose in this area, like survival, movement, pregnancy rates, and the potential impacts of winter ticks.

“This year, captures were conducted in February, when ticks are fully active on a moose’s body. Earlier than that, the ticks are often in the nymph stage and too small to see,” said WDFW Ungulate Specialist Samantha Bundick. “We intentionally did the captures later this year so we could see the ticks.”

After darting a moose with immobilizing drugs from a helicopter, a team of WDFW staff that specialize in ungulate capture and handling work together to quickly collect biological samples such as blood for pregnancy testing, fit each moose with a tracking collar, and conduct a systematic assessment of tick loads. This involves using a comb cut to a length of 10 centimeters to separate the hair along a line transect and count all the ticks that intersect the comb. In this case, the biologist does four passes on the shoulder and four on the rump of each moose. The whole process is completed in about 20 minutes.

A biologist combs moose in two different captures in February of 2024.

“The point isn’t to find out exactly how many ticks are on each moose but to see how different levels of tick burden impacts moose survival and their ability to raise calves,” Prince said.

When a collared moose dies, the collar alerts WDFW biologists who track down the carcass to investigate. So far only one collared moose has died, which was an older animal experiencing hair loss from ticks.

“It’s one more factor to look into as to why a moose died,” said Prince. “By comparing tick data from multiple years of doing these captures, we might be able to tie tick impacts to weather conditions.”

Warmer temperatures associated with climate change could increase tick loads on moose, which could negatively influence moose survival, reproduction and abundance. As for what was determined about the health of moose following this first year’s work, there’s still a lot to learn and it varies by area.

A moose collaring effort in northeast Washington in winter of 2024.

“It’s too soon to tell but we were expecting to find more ticks due to this year’s mild winter,” said Biologist Bundick. “For the most part, their coats looked really good. Mount Spokane moose looked good but in the Five Sisters area outside the Clayton and Deer Park areas, they didn’t look as good.”

Future years of this project will include additional captures and continued data collection in northeast Washington, and the knowledge gained will be used by wildlife managers to best manage this species in the face of significant threats like climate change and disease.



The Washington Department of Fish and Wildlife

The Washington Department of Fish and Wildlife is dedicated to preserving, protecting and perpetuating the state’s fish and wildlife resources.