When people think of the negative effects that climate change has on wildlife they often think of polar bears and the melting ice in the Arctic. But here in northern New England we have our own majestic animal that is being threatened by milder winters -- the moose.
The New Hampshire Fish and Game Department, in partnership with the University of New Hampshire, is in the first year of a three-year study into the causes of moose mortality and how changing weather patterns may be affecting the animals. Researchers are collecting fur, blood and tick samples to evaluate the animals' immune systems and investigate whether winter ticks are the main factor in the declining population or whether there are other causes, the Associated Press reports.
That analysis is just starting, but biologist Kristine Rines said that about 20 percent of the moose were thinner than they should be and were carrying winter tick loads that appeared heavy.
Vermont wildlife officials are keeping an eye on this disturbing trend as well, including through samples taken at weigh-in stations during last fall's moose hunt season.
The parasites of greatest concern to state biologists are winter ticks and brain worms, Cedric Alexander, a Fish and Wildlife biologist and the state's moose project leader, told the Burlington Free Press. These are tolerated by deer (85 percent of whom carry the brain worm), yet can be lethal to moose. As the deer range has expanded north, and the two types of mammals share habitat, moose have become the "abnormal hosts" of winter ticks and brain worms.
Nine percent of the moose found dead in Vermont from non-hunting deaths show signs of infestation with brain worms, Alexander said. The worms can damage the moose's central nervous system, slowly paralyzing the animal on one side. As for ticks, a greater threat is anemia from blood loss caused by thousands of ticks feeding on moose, the Free Press reports.
"The amount of blood that 30,000 ticks can consume is several times the amount of blood in the animal," Alexander said. The energy required to try to replenish the blood supply, especially for moose calves, can be beyond the animal's capacity in winter, when larvae hatch, Alexander added.
Also, Rines told the AP, "They have a reduced immune response, so there are a lot of secondary infections that can drag them down. As a result, in April, when you have a bad tick year, you have a lot of mortality. These animals literally just drop dead."
If there's snow on the ground when the ticks naturally drop off the moose in April, the ticks die without reproducing. But shorter winters have boosted their numbers. What's more, biologists are starting to see more adult winter ticks on moose in the fall, instead of just larval ticks, which suggests that these ticks may be able to cycle quicker than originally thought.
Vermont's moose population is about 2,500; the long-range management plan calls to raise the population to 3,000 to 5,000 animals. That may be difficult if the winter tick and brainworm problem gets worse, especially when you consider that the current birth rate for moose -- 1.13 per mature cow -- is below the optimum healthy rate of 1.4 to 1.7
New Hampshire has about 4,400 moose, down from a peak of about 7,600 in 1996. Some of that decline was by design, Rines said, as the state sets goals for the population based on what the public desires. In some years, for example, the public wants fewer moose because moose-vehicle collisions have become a problem.
Ironically, while researchers are examining the possible effects of climate change on our moose populations, motor vehicles are still the biggest threat to these animals. Since the beginning of Vermont's moose study in September 1980, nearly 70 percent of non-hunting moose deaths were due to collisions with motor vehicles.
What some people may not be aware of is that moose are attracted man-made salt licks that occur where road-salt runoff accumulates in the soil. So pay attention to those Moose Crossing warning signs on Vermont roads and highways. The Vermont Fish & Wildlife Department recommends reducing speed to 40 mph or lower when traveling through these areas, especially during the non-winter months and during the hours of dawn and dusk.
Believe us when we say you don't want to have a collision with a moose. Not only would it be bad for the moose, but given that these animals weigh anywhere from 600 to 1,400 pounds, it wouldn't do you or your car any good either.