Does this moose stand a chance?
By Joseph Hall,
February 20 2017
Beset by ticks, threatened by a parasite and vulnerable to warming, Canadas moose are under threat. How worried should we be?
They’re not likely to join polar bears on climate change posters – just yet.
But moose – equals of the beleaguered Arctic ursine as Canadian icons – are rapidly losing ground to a warming climate, many experts fear.
“Hopefully we won’t see (a poster of a) moose on the isolated patch of forest left,” says Julee Boan, a program manager for Ontario Nature in Thunder Bay.
But we could. The moose could be for the forests what the polar bears have been for the ice caps “the sign on the front line.”
In Boan’s Thunder Bay area alone, moose populations have plummeted by some 60 per cent in a decade, provincial wildlife management surveys show.
Moose numbers have also declined precipitously in Nova Scotia, New Brunswick, southern Quebec and eastern Minnesota, says Dennis Murray, a moose expert at Peterborough’s Trent University.
And while other areas across their vast North American range have seen static or even increased moose populations, there’s a worrisome trend overall, Boan says.
Across Ontario, for example, moose populations have fallen by 20 per cent in the last decade, she says.
The latest provincial estimate pegs the moose population in Ontario at around 92,300 – down from a high of 115,000 early last decade.
In an area of northwestern Minnesota one moose population has likely gone extinct, says Murray. He adds, however, that most experts believe the declines are now a largely localized phenomenon.
“The problem isn’t as severe everywhere,” Boan agrees. “While I don’t think we need to be alarmed necessarily at this point – we need to be very worried and we need to be focusing our energy on it,” she says.
As we ratchet up any focus or energy on the moose, however, untold numbers of the forest giants are suffering horribly as their numbers fall – afflicted by maladies and habitat shifts that are all related to climate.
Tick infestations that are literally pestering and bleeding the beasts to death.
A neurologically debilitating parasite known as “brainworm” that’s being spread to moose from encroaching white-tailed deer populations.
Warmer weather patters that may be disrupting a metabolism fine-tuned to frigid temperatures.
The opening of new logging roads that allow hunters and wolves better access to the animals, the largest of all deer species.
Boan of Ontario Nature says some of the results can be “hard to watch.”
“Itq’s horrific, when you see a moose with 80,000 ticks or 60,000 ticks or whatever (and) no hair by the spring,” Boan says.
That global temperatures are rising is clear to all but the most purblind deniers, says Boan, whose charitable conservation agency represents more than 30,000 members and 150 wildlife and wilderness groups across the province.
“The last three consecutive years have each been the warmest on record, so we know climate change is happening,” she says. But science suggests that “northern latitudes are going to experience those changes more significantly.”
Some of those northern reaches, of course, are where the moose roam. They live largely in a broad swath of forested land that crosses the continent from ocean to ocean and stretches from subarctic regions down into patches of the northern United States.
Right near the centre of that boreal bloc is the Thunder Bay region, where winter temperatures typically hover between -10 C and -20 C most days, Boan says.
“This year we had 10 consecutive days above zero in January,” she says.
These types of temperature shifts can lead to explosions in tick populations, says, Maria Franke, curator of mammals at the Toronto Zoo.
“There’s been a record of ticks found on an individual moose of like 83,000. Can you imagine?” says Franke, adding the natural average is around 3,500.
The excessive load drains the animal’s blood.
Franke says warmer winters allow ticks to reproduce at a much more rapid rate, with fewer eggs and larvae being killed off by extreme cold snaps.
The zoo, which has three female moose in its collection, is conducting a study of tick-borne disease in the Toronto region.
Murray also says climate change is likely responsible for increased interactions between moose and white-tailed dear, which are moving further north as the winters warms.
They’re carrying with them parasites and ailments to which they’ve become largely immune but are harmful to moose – much like Europeans brought pestilence to non-resistant indigenous populations in North and South America after Columbian contact.
“There are a number of parasites that are transmitted by white-tailed deer to moose that “don’t really seem to damage (the deer) a whole lot,” Murray says
“But they’re potentially lethal to moose. They can kill them and cause population decline.”
These parasites include brainworm – or Parelaphostrongylus tenuis – which can leave moose with symptoms much like those seen in cattle afflicted with Mad Cow Disease.
These symptoms can include disorientation and blindness and leave the weakened animals lolling their heads and stumbling in circles towards an almost certain death.
Other ailments that spread from deer to moose include liver fluke and winter tick, says Murray. The former is a large worm species that invades the moose’s liver, turning the animal’s own immune apparatus against the organ.
“The moose’s immune system walls off these parasites by trying to create these big cysts,” says Murray, head of Trent’s Integrative Wildlife Conservation lab. “And if you get 100 of these (worms) in the liver, you can have a liver that essentially becomes one big, massive cyst.”
Winter ticks are – again – relatively benign to their deer hosts, but are pestilent to moose, causing some to scratch against trees or rocks until their hair is all but gone.
“There’s a phenomenon known as ghost moose,” says Murray, who uses mathematical models to project the size and locations of future moose populations and the pressures they may face.
“This is basically a moose that would be walking around with essentially no guard hairs because they’d torn them all off and it just looked like the moose was white.”
Franke says warmer temperatures themselves may be noxious to moose, interfering with a metabolism that evolved to deal with colder weather.
“Moose are built for the cold, they want it cold,” she says.
Franke says the animals can “thermoregulate” in the summer by slipping into a cool lake or pond.
But on warm winter days – with ice still covering the waters – moose don’t have that option and can suffer heat stress, she says.
Murray says scientists are studying the metabolic threats of warmer weather on moose but that there’s currently no conclusive evidence that the animals cannot adapt to higher winter temperatures.
Murray also points to increased logging, again made easier by warmer temperatures, as another potential cause of moose declines.
Not only do more northerly operations further fragment moose habitat but they also supply hunters and wolves with easier access to their quarry, he says.
“So you get smaller and smaller blocks of pristine habitat, making moose more susceptible to being taken out.”
It’s been suggested that new logging roads that have allowed wolves further access into Alberta forests are leading to the extinction of several boreal caribou populations in that province, Murray says.
Earlier this month an Ontario wildlife group urged this province to ban hunters from killing young moose, the Star’s Kristin Rushowy reported.
“It doesn’t make sense – in a population of animals that is declining – that you are taking out the future breeders,” said Dave Pearce, manager of forest conservation for the Wildlands League.
Pearce also called on the province to create “moose refugee areas” and increase funding for monitoring and research.
A spokesperson for Ontario’s natural resources minister said the government has completed the second phase of its Moose Project, which included examining “the factors affecting moose, and actions that could be taken to address those factors.”
“This resulted in new moose population objectives and changes to moose hunting seasons to address concerns about fewer calves and fewer moose being observed in recent surveys,” Emily Kirk said. “These changes are necessary to help sustain and ultimately grow Ontario’s moose population.”
Kirk said the government will “continue monitoring moose populations and will evaluate the need for additional changes to ensure a healthy and sustainable moose population here in Ontario.”
Over time, of course the vast belt of boreal forest the moose inhabit will itself shrink through climate change, Boan says.
“That band is going to start getting smaller and smaller and the species that rely on that forest are going to be under an incredible amount of pressure,” she says.
And forestry science, she says, is only now beginning to understand how climate shifts will alter the forests that remain.
While Murray says a true crisis is not currently upon us, he predicts that within 70 years, large swaths of Ontario will become inhospitable to moose due to global warming.
Compared to the polar bear, however, Murray says moose have some built-in advantages that may make them more adaptable to a changing climate.
Polar bears, he says, exist in a very narrow niche that leaves them virtually no chance at existence absent the specific, icy conditions to which they’ve been adapted.
Moose, he says, are more “generalist” in interacting with the environment. So it’s likely they can withstand changes in habitat for longer periods.