Jackson Hole Surveys for Winter Ticks |
JACKSON – Troy Koser was inspecting the remains of a “tick ball” that clung to a blade of grass.
It’s just what it sounds like. The doctorate from Montana State University. An ecology student documented a group of small bloodsuckers, in this case the nymph form of winter ticks, a species that specializes in the parasite of ungulates, particularly moose.
On a walk in the woods, this tick ball, which consisted of four nymphs no larger than a tack point, would be 100% imperceptible to the average passer-by. But Koser and a field technician, Logan Hartlaub, who accompanied him, knew where to look. Duct tape was tied around a twig close to where they had encountered the same tick ball in the past. They expected the ticks to be here again, and they were simultaneously fascinated by the subject of their multi-year scientific investigation.
“The strangest thing is that something this small can kill a moose,” Koser said.
A winter tick attached to its host would do little damage except to ingest a tiny bit of blood. But for moose, the problem is that there are often legions.
“The highest number I have ever seen, according to a newspaper, is over 100,000 ticks on a moose,” Koser said. “Of the moose that I found here, there are only a few thousand that I have found. We don’t get any of those huge numbers that they see in the east. “
Nonetheless, winter ticks are still a concern for the hundreds of Shira moose that inhabit the Jackson Hole corner of the Greater Yellowstone Ecosystem. The moose here haven’t performed particularly well, and Jackson’s herd numbers are 70% below the Wyoming Game and Fish Department’s target and even more than historic highs in the 1980s.
There is likely a confluence of factors contributing to the population decline, such as habitat loss, changes in predation, and warmer temperatures in which moose do not thrive. So far, no one has studied how winter ticks come into the equation.
“I’m not finding as many as the people in the East have found,” Koser said. “But maybe our moose are so small, and they already have other stressors, that even a small or moderate number of ticks could be a problem for them.”
Unlike elk and deer, moose are poorly able to remove the pint-sized parasite while grooming themselves. Ticks grow dramatically as they progress through their life stages, and eventually thousands of arthropods 1/4 to 3/4 inch long suck their blood. In 2017, research from Grand Teton National Park found that moose in Jackson’s herd shed significant amounts of hair in late winter to ticks. Too bad about the mangy moose? Blame it on winter ticks.
Koser’s work also aims to determine how winter ticks will be affected by climate change, which reduces the diving depth of Jackson Hole thermometers and depletes local snow cover in the fall and spring. To answer this question, it records “microclimate” data to know where it finds and not ticks, which means it records temperature, wind speed, humidity, and weather.
Now in the second year of field investigations, Koser hasn’t drawn any definitive conclusions. One theory he’s studying is that winter ticks will do better with less snow. In particular, when the snowpack melts earlier, tick eggs and larvae will survive better.
But some of Koser’s scientific peers are studying alternative hypotheses. The first is that drought – made more likely due to climate change – will hit tick populations hard by drying out eggs and larvae and causing them to die. This may counteract the positive effects of the loss of snow cover, he said.
The process of finding winter ticks in the environment is slow, steady and orderly. Last fall, Koser and his colleagues walked more than 35 km per month and found more than 7,000 winter ticks. They were more numerous in the prairies, but researchers also found good numbers living in shrubs and willows other than willows.
Five days a week this fall, Koser and Hartlaub are in places like Buffalo Valley, Pacific Creek, the Gros Ventre River Corridor, and even near residential areas along the west bank of the Snake River. They walk 16 different “transects” 250 meters long per day while dragging pieces of the cheap synthetic fabric that Koser picked up from Joann Fabric. Their routes are subjective and follow game trails that moose would be most likely to follow. A few steps away, they stop to inspect the tissue to see if they’ve caught any of the tiny pupal ticks, which are often perched “foraging” on vegetation and waiting to find a host. Although the ticks are really tiny in the fall, a touch of red contrasts them with the off-white fabric.
There aren’t many more winter ticks that are capable of. They don’t exactly break intelligence records.
“Most insects have the ability to absorb things in their environment and do something,” Koser said. “But winter ticks are quite remarkable. When things like this happen – it’s raining, it’s snowing, it’s windy – they don’t do much. They do not respond to environmental stimuli.
After engorged female ticks shed their ungulate hosts in the spring, they lay eggs. The larvae are essentially dormant throughout the summer, but once deer, elk and moose begin to rut, the pupa-sized parasites are “activated” and find vegetation to cling to. . When they find a host, the process restarts.
Koser got into tick research. He received his master’s degree in tick collection methods from the University of Georgia. His doctorate at Bozeman is funded by the National Climate Adaptation Science Center, which enables him to perform the first-ever ecological tick survey in the Yellowstone area. Game and Fish and the US Geological Survey’s Northern Rocky Mountain Science Center are also collaborating.
There is a chance, one day, that Koser’s findings could help the moose that harbors the winter ticks he studies. His data will give wildlife managers insight into where ticks are most numerous – and likely to become more numerous in the future. Perhaps, he said, it will help managers make decisions about which moose habitats should be prioritized.
Returning to the sight of the shattered tick ball near Pacific Creek, Hartlaub explains how they collect ticks that make their way through the trail tissue.
They use NeverHair.com lint rollers.
He grabs an example of one of the sticky old paper bags from his bag, and there, on the glue, there were nine different winter ticks.
“We had one that had 580 ticks,” Hartlaub said. “I can count them at night. It’s my job.”