October 10, 2022
By Dr. Dave Samuel
Winter Ticks Killing Moose Calves
In the northeastern areas of America and Canada, research is finding that winter ticks are really bad for moose calves. Research done in Alberta in the late 1990s showed the same thing, but now things are worse. Here’s why:
In recent years, the moose population in Maine has been growing. Same is true for New Hampshire and southern Canada. As moose numbers grew, tick numbers did, too. Ticks hatch from eggs in the fall and the tick larvae then climb onto a passing moose calf. They’ll feed on blood from the calf all winter, and the larvae then reach adult size from February till early May. After feeding, the female ticks drop off in the leaf litter. Then in early summer, each tick lays up to 4,000 eggs. In early fall, these eggs hatch and the larvae climb onto vegetation waiting for a host (often a moose calf). When a moose calf walks by, it can pick up thousands of larval ticks. The larvae, nymphs, and adults feed on the calf’s blood for months, and the health of the calf ultimately deteriorates.
Climate change has led to warmer and longer fall weather in recent years. This means that moose are exposed to more ticks before snow arrives. This leads to situations where a single moose gets infected by as many as 100,000 ticks in one season. The moose gets inflamed skin and rubs on trees, causing hair loss. Both adults and calves can rub so much that they rub off much of their hair, giving them a gray color. These moose were called “ghost” moose before people knew what was causing this. Of course, rubbing off fur in winter isn’t good for the moose.
The death rate for calves in Maine has reached an all-time high due to ticks. Researchers there radio-collared 79 moose calves in one winter, and 60 were dead by May. The 86-percent mortality was the highest ever recorded in Maine. Those huge numbers of ticks cause calves to literally bleed to death over winter and early spring.
Winter ticks on moose are not transmitting disease, only feeding on the same moose, over and over. If a moose calf has 30,000 winter ticks, in March and April the daily proportion of total blood volume lost is almost 60 percent. Replacing that lost blood is more difficult when forage is reduced in late winter. Thus, survival at these levels is nearly impossible for the calf. Adult bull moose with 30,000 winter ticks have a daily proportion of total blood volume loss of 18 percent, and cow moose lose 15 percent. That’s still not good, but it’s survivable.
What can be done? To determine whether a reduction in the moose population can lessen the impacts of winter ticks, Maine has set aside a large area with moose harvests increased in half that area. The study will go on till 2025, and I’ll update you as that progresses. One thing is certain: Climate change is impacting moose calf survival, and it is doing that via winter ticks.
Ukraine War Impacting Wildlife
Most of us knew little about Ukraine when it was attacked by Russia. Actually, we still don’t know a lot, except that bombs are destroying buildings and people are leaving their homes. A little research shows that Ukraine covers 233,000 square miles, which is about the size of Texas. Around 30 million people live in Texas, and 40 million live in Ukraine.
Ukraine is a beautiful country, with lots of wildlife and wildlife habitat. Troop movements, sewage from bombed septic systems polluting fresh water, and forest fires caused by bombs are all impacting wildlife, migrating waterfowl, and wildlife management.
Ukraine has many important wildlife preserves, and some have been devastated by the war. Money from ecotourism has been lost. Some have suggested that the impacts of the war on Ukrainian wildlife maybe never be repaired. Truly sad on many fronts.
Don’t Fence Me In
As the world’s human population continues to grow, so does our need for fences. In 2009, I drove across Nebraska on the way home from the Pope and Young Convention in Colorado. Interstate 80 runs 480 miles across Nebraska, with fencing on both sides of the highway. Along the highway, a car was parked with its emergency lights blinking. I slowed and noticed a man standing by the four-foot, welded-wire fence that also had two strands of barbed wire across the top.
Apparently he was trying to rescue a deer caught in the fence, so I stopped. The doe was bawling and in trouble, and from all appearances it had been there a long time. I have no idea how the man spotted the deer, but now he had a big file and was trying to use it to cut the fence’s welded wires. I helped the man with the file, and after 15 minutes we broke the wire and helped the deer escape.
Her leg appeared hurt, and she moved away slowly at first. But after 50 yards, she kicked it into high gear and disappeared. Wet from the morning dew, as we went back to our cars we felt like we’d accomplished something.
Fences are everywhere, and livestock fencing isn’t used only in our country. In Africa, livestock fences inhibit the normal movement of many migratory species. Since 9/11, the trend in many parts of the world is to build security fences to keep people from moving from one country to another, especially in rural areas. That explains why there’s a 2,200-mile fence separating Mongolia from China. One radio-collared gazelle was tracked for 20 days along 30 miles of that fence that it wanted to cross.
As noted above, sometimes animals get tangled up in a fence and die from starvation. It happens all the time somewhere in the world. Of course, there’s the fence we’ve heard a lot about that separates parts of the U.S. and Mexico, but similar fences between countries are being built all over the world. Maybe some are necessary, but none are good for wildlife.
We’ve got an estimated 620,000 miles of fences in the Western U.S. One paper I read noted that we have become “fence-blind.” We drive by these fences, and they’ve been there forever, yet we just don’t see them anymore. We see the cattle but not the fences. And we see the antelope but don’t recognize the problems fences cause for them.
Fences prevent migration, concentrate wildlife, and thereby lead to disease and even genetic problems in certain species. They keep wildlife from water and alter natural predation. Obviously, the ecological repercussions of fencing are complex, but we need to pay more attention to the wildlife consequences of these fences.