State biologists hope to learn if issuing more moose-hunt permits might cut down on winter tick infestation, leading to a healthier herd. Photo courtesy of Jack Gaudet

State biologists are proposing an increase in the number of cow moose permits issued in part of a northern Maine hunting district to determine whether lowering moose population densities could reduce winter tick infestation.

In what’s called an “Adaptive Unit Hunt,” an additional 550 cow moose permits would be issued in half of hunting Zone 4 – just northwest of Baxter State Park – if the Maine Department of Inland Fisheries and Wildlife’s Advisory Council approves. The IFW will present the proposal in March for next fall’s hunt.

The additional permits would be on top of the total issued statewide. That number will be decided this spring, but is unlikely to change much from the 3,135 allotted last year, said Maine Moose Biologist Lee Kantar.

Kantar told the council at a meeting Tuesday that a recently completed radio-collar moose study – which involved 520 moose over seven years – showed winter ticks are the “primary mortality driver” for moose calves. Maine has the highest density of moose in the contiguous U.S., and among the highest in North America.

“We know that moose densities at much lower levels have much lower parasites. So if you reduce the primary host to winter tick – the moose – and lower the density of moose, you’d break the winter tick cycle,” Kantar said. “We want to demonstrate to the public whether reducing moose densities can or cannot break the tick cycle.”

After aerial surveys in 2012, IFW estimated Maine’s moose population at about 76,000. But Kantar said Tuesday the herd now numbers 60,000 to 70,000.

Kantar said the toll taken by winter ticks – as many as 90,000 ticks can feast on a single moose – has been exacerbated by a warming climate.

Winter ticks have been documented in Maine since the 1930s. But Kantar said winters in northern Maine are two weeks shorter on average than they were 30 years ago, according to studies by the University of Maine. This has allowed the parasite to survive in greater numbers in Maine’s core moose range than ever before.

“Two weeks may not sound like a lot, but when it comes to wildlife, it’s very impactful,” he said. “We have a lot of data to suggest there is reduced moose productivity in the form of lower rates of (cows having twins), calving rates and calf-to-cow ratios.”

The radio-collar study showed that in Zone 8, the Moosehead Lake study area, the mortality rate for collared calves was greater than 50 percent in six of the study’s seven years. In Zone 2 at the northern tip of Maine, where winters are more severe, mortality among collared calves reached 50 percent in only one year.

Moose densities in North America are typically around one animal per square mile. But in parts of Maine it is as high as five per square mile, and in the proposed new study area it is up to eight moose per square mile.

The proposal calls for issuing 550 additional cow hunting permits in the western half of Zone 4 – an area that constitutes just 6 percent of Maine’s core moose habitat, but no additional cow permits would be issued for the eastern half, Kantar said. The additional permits are about three times the number issued in all of Zone 4 last year.

Biological data – such as from a new radio-collar study, harvest totals and other sources – from the two parts of Zone 4 would then be compared. The proposed study would last five years.

If the increase in hunting lowers moose densities – and tick infestations – in the study area, then additional permits could be issued in other hunting zones, according to IFW.

The proposed study area is in commercial forestland in unorganized territories and not near any traditional moose-watching destinations, such as Rangeley, Greenville or Millinocket. 

IFW Commissioner Judy Camuso said she is confident the public would support the study.

“When we did the surveys for the Big Game Plan, the one thing that people consistently said was they weren’t concerned with population levels of any particular species, but they really wanted healthy wildlife populations,” Camuso said.