Climate Change Now: “Ticks Cover their Bodies Like Shingles on a Roof”
Posted by Richard Conniff on December 5, 2014
They call them “ghost moose.” These pale beasts have lately come to haunt forests across the northern United States. But they aren’t at all like the revered Kermode bears of Canada, which owe their cream coloring to genetics or, as some First Nations believe, to supernatural powers. Ghost moose are white because of winter ticks. More precisely, they are white because climate change makes them vulnerable to winter ticks. That may sound crazy at first. For most of us, climate change can seem like an abstraction, with consequences that we may not have to face till some vague time decades or centuries in the future. But the spectacle of a moose with thousands upon thousands of engorged winter ticks clinging to its body has a way of making it seem painfully here and now.
“The ticks cover their bodies like shingles on a roof,” said Kristine Rines, a wildlife biologist and leader of the New Hampshire Fish and Game Department’s Moose Project. “Fat, ugly shingles with little creepy wavy legs.”
What’s climate change got to do with it? In the past, winter ticks (Dermacentor albipictus) were mostly found on white-tailed deer, which live in slightly warmer climes farther south. These ticks typically lay their eggs in the spring, and the young develop during the summer. By fall, clusters of tick larvae are waiting in the undergrowth, and when a deer brushes against them, the young ticks latch on. But the deer are used to it. They groom the ticks off themselves while they’re still young and easy to dislodge.
Not so for moose. They have no history with this horrific nuisance and don’t seem to make any attempt to groom the off the immature ticks from October until February. By then, it’s too late: the adult ticks are too appallingly numerous to do much about it. The moose only get relief in April, when the ticks generally drop off to renew their reproductive cycle, laying eggs for the next generation.
In the past, any winter tick that happened to fall off a moose would find itself dropped onto snow-covered ground, where it would freeze or make for a highly visible snack for passing birds. But with shorter, warmer winters, it’s now normal for snow to melt by April in Vermont and New Hampshire. That lets winter ticks survive and reproduce there, as well as in other states along the southern part of the moose’s range, including Montana, Idaho, and Minnesota.
Even more ticks pile onto the moose the following winter. In their efforts to dislodge these pests, the moose rub so aggressively at their dark brown outer guard hairs that they break them off close to the root, leaving only the whitish stubs behind. Moose with especially bad infestations—as many as 50,000 ticks—may remove 80 percent or more of their outer hair layer, giving them their ghostlike appearance. The moose often can’t survive the cold without their winter coats. Or they die from anemia caused by the loss of so much blood. (Female ticks swell to the size of small grapes when fully engorged). Thanks in part to winter ticks, moose populations in many states are now declining,
Does that matter? Moose numbers have fluctuated wildly over the past few hundred years. They had practically vanished from New Hampshire and Vermont by the 1890s, because of hunting and conversion of forests to farmland. Then in the 20th century, forests reclaimed farm fields in northern New England, and moose populations rebounded so successfully that fatal traffic accidents became commonplace. The moose also made themselves unwelcome by knocking down livestock fencing and demolishing maple syrup tubing as they moved through the forests.
New Hampshire’s Kristine Rines doesn’t expect winter ticks to threaten the long-term survival of moose in her state. As moose densities decline, so will mortality from winter ticks. But climate change is also bringing other threats to the northern forests, including brainworm from deer extending their range northward into moose habitat. Moose infected with this parasite become disoriented, often turning repeatedly in circles before they eventually become paralyzed and die. That has caused “dramatic moose reduction, if not extinction, in several areas in North America,” she said, including parts of Minnesota, Nova Scotia, and New Brunswick.
To Rines, the solution is relatively clear, if not easy to achieve. “We have to wrap our arms around climate change,” she said. People tell her that there’s nothing to be done about it—or worse, that it’s just a myth, and “It makes me want to retire,” she said, with a bitter laugh.
But Rines knows that there is plenty that people and governments can do to address climate change. She also knows that it’s not just the moose that are at risk: The purple finch—New Hampshire’s state bird—has been shifting its range northward, out of the state. The threatened Bicknell’s thrush depends on high-elevation spruce fir forests, common in New Hampshire but also threatened by the changing climate. Sugar maple sap has already begun losing its sweetness, and some researchers believe sugar maples could disappear from New England altogether.
So think of those ghost moose as a harbinger, even the ghost of Christmas yet to come. A few inches of sea level rise, or a couple of degrees change in average temperature may not seem like much. But when we think of a lone moose stripped bare in the winter forest, or circling in confused agony, and when we envision a New Hampshire with no moose at all, or a Vermont without sugar maples, then maybe each of us can dimly begin to hear the Jacob Marley’s chains we all drag behind us. What we are facing is a future in which we have lost not just our regional identities, but also our souls.