Ticks decimating moose population in Maine

By Isabel Adler

The moose that have long been a symbol of Maine are facing a serious threat: ticks. Peter J. Pekins, a Professor of Natural Resources and the Environment at the University of New Hampshire, has been monitoring tick populations on moose since 2014. A New York Times article reported that in that time, the maximum amount of ticks Pekins has found on a calf has been around 100,000, but he estimates this number to have been even higher in the days preceding the calf’s death. Of the 179 moose calves Pekins has tracked, the average number of ticks a calf was host to was 47,371.

The increase in tick population can be traced back to the impacts of climate change, as Pekins points out that “shortening winter plays to the advantage of the tick.” As New England autumns and winters have begun to become more moderate, ticks have been able to spend longer amounts of time than usual looking for a host, allowing for calves to become covered in clusters of thousands of ticks. The rapid growth of the winter tick population is not only due to warmer temperatures, but also because there have been more moose to feed on. Since the 1990s, moose populations have been increasing in New England after being nearly eradicated by human impact — in an interview with the New York Times Pekins divulged that “Maine and New Hampshire had less than 50 moose in the 1970s.”

Part of Lee Kanter’s job, a New Hampshire native who now serves as Maine’s official moose biologist, is to recover deceased moose within the first 24 hours of their death to do complete field necropsies he told the Sun Journal in an interview.

Through doing these analyses, biologists throughout New England have found that winter ticks have been killing moose calves at an alarming rate. Though both adult moose and calves are impacted by the ticks, calves are the most likely to perish due to being smaller in size. The recent boom in the population of winter ticks, due in large part to climate change, has left thousands of ticks looking for hosts to feed on. Some unlucky calves become so covered in ticks that they are unable to survive, as the amount of ticks feeding on them drains their blood at rates more rapid than their ability to replenish its supply. Most calves found killed by ticks are heavily anemic and incredibly thin due to the amount of blood loss they’ve been subjected to. It’s not that the calves aren’t eating enough, but rather that they simply cannot access enough nutrition to remedy this amount of blood loss.

In order to tag and monitor moose, technicians first search for the animals from a helicopter, then shoot them with a net in order to trap them. Once on the ground technicians blindfold the moose, collar it, take blood and fecal samples, and do a tick count before releasing the moose. Then, when the moose eventually dies, the technicians are alerted via text and locate the moose to gather samples.

In an interview with the Sun Journal, Kanter stated that Maine has collared more than 380 moose to better understand their dynamics and monitor their health. Since the beginning of the study, Kanter has found that April has always been the month with the most moose deaths. Over the past few years, researchers have found that around 70% of the moose calves they’ve tagged throughout New England have died due to ticks.

Some have suggested that an increase in moose hunting would control the tick population. Fewer moose would mean fewer hosts for winter ticks to feed on, resulting in their population decreasing. Though increasing the volume of moose hunting permits has been discussed, in actuality, the opposite has occurred as fewer hunting permits have been awarded in recent years due to the decreasing moose population.

Shawn Sage, the president of the Buxton-Hollis Rod and Gun Club, expressed concern in an interview with the Portland Press Herald over the decrease in permits as the “moose population puts a lot of money into the state”, referencing revenue generated from hunts of the beloved Maine state animal. Sage hopes that biologists can soon figure out a method for combating winter ticks similar to the chemical treatments given to domesticated animals, but as of right now there are no chemical treatments being implemented.

Biologists such as Kantar are hoping that as winter ticks continue to kill moose calves and consequently have fewer hosts to feed on, their populations will also decrease, eventually reaching a new point of equilibrium and no longer posing a threat to calves.