Caribou migration linked to climate cycles and insect pests

DECEMBER 12, 2019

by University of Maryland

Caribou weakened by harassing insects in the summer take longer to migrate to calving grounds the following spring. This means calves have less time to fatten up before winter. As Arctic summers continue to grow warmer and favor more insects, caribou populations could suffer. Credit: NPS/Kyle Joly

Caribou, the North American cousin of reindeer, migrate farther than any terrestrial animal. They can cover thousands of miles as they move between winter feeding grounds and summer calving grounds. But many caribou herds are in decline as the warming climate changes much of the landscape they depend on. Inedible shrubs are rapidly encroaching on the tundra, and more frequent forest fires and disease are destroying the trees that provide caribou with lichen for food. The role of climate on their migration patterns has never been well understood, but knowing what drives caribou movements is crucial to predicting the future for the iconic species that plays a key roll the ecological and economic stability of the Arctic region.

A new study led by a University of Maryland biologist discovered two unexpected drivers for migration timing that dispute long-held assumptions and provide insight into potential future effects of climate change on caribou. First, the study found that caribou herds all across North America are triggered to start spring migration at roughly the same time by large-scale, ocean-driven climate cycles. Second, despite a synchronized start, arrival at their respective calving grounds depends on the previous summer's weather conditions. Warm, windless summers that favored insect pests lead to poorer maternal health and delayed arrivals at the calving grounds the following spring.

The study, which accounted for approximately 80% of all North American migratory caribou, is the largest caribou migration study to date. It was published in the December 12, 2019 issue of the journal Ecosphere.

"This was completely unexpected," said Eliezer Gurarie, an associate research scientist in UMD's Department of Biology and lead author of the study. "There was no reason to think that herds that calve near the Hudson Bay in the East would begin migration at the same time as the herds along coastal Western Alaska, or that summer conditions would play an important role in the following spring migration. Prior to this, it had been assumed that migration timing depends on some combination of snowmelt and availability of useful vegetation at the endpoint of the migration. Neither of those held up."

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A small town's economy. Endangered caribou. Which do we protect?

British Columbia faces extreme protections to help the caribou, which would decimate the economies of towns like Revelstoke – prompting a ‘moral crisis’

Cassidy Randall

Mon 15 Jul 2019 06.00 BSTLast modified on Mon 15 Jul 2019 06.48 BST

On 15 April, with less than a week’s notice, 700 people squeezed into a community center in Revelstoke, British Columbia, for a last-minute meeting with Canadian government officials. Snowmobilers, skiers, loggers, activists, berry-pickers and business owners were all drawn there to discuss the threat of a widespread closure to the mountains that are the lifeblood of this community.

At stake: three herds of caribou. Or, potentially, the entire town.

British Columbia is rushing to put plans in place to manage the endangered woodland caribou before the Canadian federal government loses patience and invokes the most extreme protections across herd ranges, which would likely involve year-round blanket closures to the mountains to protect caribou habitat. Such mass closures would decimate the economies of neighboring small towns, like Revelstoke, that depend on those same mountains for tourism and resource extraction, like logging.

This debate leaves residents with a troubling question: how much are they expected to sacrifice to save a dying species?

A recently released UN report reveals that the planet is on the brink of the sixth mass extinction. Caribou have long been a symbol of the north, once roaming in vast herds and numbering at least 40,000 in BC alone. Known as “grey ghosts” for their elusive nature, they are in danger of becoming literal ghosts: in May 2018, the federal government declared that the remaining southern mountain population of woodland caribou in the country’s western reaches faced an “imminent threat” to survival. The South Selkirk caribou herd that roamed the US border disappeared earlier this year, taking with it the last caribou from the lower 48. And many of the herds left in Canada have too few animals for a likely chance at long-term survival.

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An alternative to wolf control to save endangered caribou

Researchers study the effectiveness of a new government strategy to stabilize the caribou population by focusing on the reduction of invasive moose populations, indirectly lowering the density of the caribou's primary predator

Date: August 29, 2017

Source: PeerJ

Summary:

The iconic woodland caribou across North America face increasing predation pressures from wolves. A short-term solution to caribou conservation would be to kill wolves. But a new government policy looks at reducing the invasive species moose numbers propping up the wolf population. Researchers have now evaluated the effects of this policy on the caribou population.

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Wolf cull will not save threatened Canadian caribou

Study suggests Canadian government strategy is not enough to preserve caribou population in the boreal forest.

Emma Marris

20 January 2015

Boreal caribou populations have declined as industrial activity in Canada's boreal forest has increased.

Since 2005, the Canadian government has shot nearly 1,000 wolves to protect a herd of threatened boreal caribou in the forests of Alberta, Canada. But a recent study suggests that this approach has limited benefit.

It is enough to keep the population of caribou from shrinking further, but it will not allow the animals — a geographically distinct population ofRangifer tarandus, which in Europe is known as the reindeer — to increase their number, finds the November analysis published in theCanadian Journal of Zoology1. Such an increase would require placing new limits on industrial development in Alberta, a conclusion that adds fuel to an ongoing debate about the ecological consequences of human activity in the boreal forest.

Caribou have been listed as threatened since 2002, mainly because much of their boreal forest habitat has been sliced into small fragments by a web of roads, pipelines, clear-cut swathes and well pads. Moose and other deer species do well in these open areas, and their populations have boomed — supporting an increasing population of wolves, which have learned to use the roads and pipelines to access caribou hiding in the deep woods.

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Caribou genetics reveal shadow of climate change

Ancient ice ages that shaped modern caribou populations may foretell animals' fate in a warmer world.

When ice sheets marched across North America 20,000 years ago during the Last Glacial Maximum, they devoured liveable areas for caribou and isolated them from their Eurasian relatives for thousands of years.

Now researchers have evidence that such climatic events have sculpted the genetics of North American caribou, which may make the animals unable to adapt to future climate change.

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Caribou Bones Reveal New Arctic Habitats

Becky Oskin, OurAmazingPlanet Staff Writer

Date: 05 April 2013 Time: 01:26 PM ET

In the dry and frigid Arctic, caribou antlers and skeletons survive on the landscape for thousands of years. For the first time, researchers are using these bones to track caribou behavior in Alaska's Arctic National Wildlife Refuge.

Both male and female caribou shed antlers, but only females shed them within a few days of giving birth. Researchers found a surprising number of antlers and newborn skeletons on river terraces in the Porcupine caribou herd's calving grounds. Tundra was thought to be the most popular calving turf.

With 170,000 animals, the caribou herd plays a critical role in the Arctic ecosystem. The study authors hope to extend their work to understand how the herd's behavior may have shifted with warmer or colder climate periods.

http://www.livescience.com/28482-caribou-bones-reveal-changing-habitats.html

New Bone Survey Method Could Aid Long-Term Survival of Arctic Caribou

Mar. 27, 2013 — A study co-authored by a University of Florida scientist adds critical new data for understanding caribou calving grounds in an area under consideration for oil exploration in Alaska's Arctic National Wildlife Refuge.

The research may be used to create improved conservation strategies for an ecologically important area that has been under evaluation for natural resource exploration since enactment of the Alaska National Interest Lands Conservation Act in 1980.

By studying bone accumulations on the Arctic landscape, lead author Joshua Miller discovered rare habitats near river systems are more important for some caribou than previously believed. The study appearing online today in the journal Proceedings of the Royal Society B shows bone surveys conducted on foot provide highly detailed and extensive data on areas used by caribou as birthing grounds.

"The bone surveys are adding a new piece of the puzzle, giving us a way of studying how caribou use the landscape during calving and providing a longer perspective for evaluating the importance of different regions and habitats," said Miller, an assistant scientist at the Florida Museum of Natural History on the UF campus and a Fenneman assistant research professor at the University of Cincinnati.

Unlike other species in the deer family, both male and female caribou grow antlers. Males shed them after they mate, while pregnant females keep their antlers until they calve, losing them within a day or two of giving birth. Newborn caribou calves also suffer high mortality rates within the first couple days of birth. The female antlers and newborn skeletal remains offer a unique biological signal for understanding calving activity, Miller said.

Continued:  http://www.sciencedaily.com/releases/2013/03/130327163304.htm

300,000 Caribou Huddle Together To Avoid Insects

Humans are not the only creatures bothered by mosquitoes and flies. They harass caribou so much that earlier this month, about 300,000 of the animals huddled closely together in Northwest Alaska to avoid being bitten and parasitized.

It's one of the most spectacular gatherings of wildlife in the world, rivaling the migratory herds of Africa's Serengeti, said Kyle Joly, a wildlife biologist with the National Park Service based in Fairbanks, Alaska.

Joly took several photos of the animals while flying a Cessna 185 earlier this month, near Cape Krusenstern National Monument and Noatak National Preserve.

"The bugs on the North Slope are pretty ferocious," Joly told OurAmazingPlanet. "The mosquitoes just harass them 24 hours per day." The warble flies and nasal bots that are out now are even worse in some ways, he said; the warbles try to lay eggs on the animal's sides and the bots try to fly up caribou nostrils to deposit eggs.

Continued:  http://www.livescience.com/21718-caribou-herds-bug-protection.html

The boys are back in town

Christmas is over - but Rudolph and his relatives don't seem to be interested in moving on.

Instead, they've taken over a farming community off New Bay Road just outside Grand Falls-Windsor. And they're posing some challenges for the people there trying to grow crops like carrots and cabbages.

Woodland caribou populations are on the decline in the province, according to the provincial Department of Environment and Conservation, but a small migrating caribou herd, Newfoundland's version of reindeer, has been taking up winter residence in Wooddale.

Wildlife official Blair Barnes has been checking on the herd, who he last counted at 67 animals on his most recent visit. However, other observers have reported numbers as high as 150.

The caribou have been coming back to the community over the past six years. They are originally from the herd at Hodges Hill, a mountain near Grand Falls-Windsor. Actually, said Barnes, it isn't a single big herd in this region, but several smaller pockets.

Some of the animals show up at Wooddale between October and November, while more of the herd make their way later in the fall and winter.

"As the years go by, it seems like there's more and more coming," said Barnes. "It's almost like they're telling their buddies, ‘there's good grub down on this farm, follow me.'"

There are three reasons for the caribou making Wooddale their migratory home, he said. First is the amount of snow on Hodges Hill, meaning the caribou find it more difficult to access their food source. The snow on Hodges Hill is "unreal," said Barnes, with deep, heavy amounts that the caribou find difficult to navigate through.

Second is that Wooddale is relatively sheltered, a good location for the animals to hide from predators such as coyotes, according to the wildlife official.

Another factor is the crops of carrots, other root vegetables and cabbage Wooddale farmers harvest in the fall.

That last point is what Wooddale farmers aren't pleased with: the appearance of the caribou in their fields.

The Fudge family grows a variety of vegetables on their fields in Wooddale, and for the past six or seven years, they have been dealing with the growing population of woodland caribou on their lands. Kent Fudge has been living in Wooddale for the past 34 years, but he said he had never seen them in numbers like this.

"I think the coyotes got them drove, because every night you can hear them on the bridge, howling," he said. "If you go out on skidoo, you can see the coyote tracks behind the caribou herd, following."

He added in the first year the animals were seen, only five or six caribou were seen. The Fudges contacted the wildlife division about the animals; officials visited the farm and expressed interest in tranquillizing and transporting the caribou back to their original herd because they feared what could happen to the animals if coyotes attacked them.

Fudge said the Wooddale numbers have grown substantially since then. "I've counted over 150 on the field at one time, but then you go down to another field, and there's another 50 or 60 there."

He added the caribou are creating problems for the Wooddale farmers, because they eat the crops when they arrive in October.

"Right now, they're eating stuff that's leftover, but we haven't had hardly anything, because we don't start harvesting until Thanksgiving," said Fudge.

"They could eat $20,000-$30,000 in crops a year, and that's just from mine and my brother's farm. And we have people out picking crops, but they don't feel safe, because the caribou are there, and the animals are that used to us being there."

http://www.gfwadvertiser.ca/News/2012-01-16/article-2865146/The-boys-are-back-in-town/1

80% decline in Caribou blamed on big industry

Christmas reindeer mystery as world's largest herd plummets 
January 2012. The world's largest reindeer herd has plummeted in size, with local indigenous people blaming the spread of massive industrial projects in the area. The George River herd, which once numbered 8-900,000 animals, stands today at just 74,000 - a drop of up to 92%.

Quebec and Labrador tundra
The herd roams the vast tundra of Quebec and Labrador in eastern Canada. Known as caribou in North America, the animals are central to the culture of the Cree and Innu people of the region.

Mining, hydro & roads
However, in recent decades large parts of the herd's range have been disrupted by a series of huge projects. Iron-ore mining, flooding vast areas for hydro-power and road-building have all taken their toll, according to Innu people.

Innu people
Innu Elder and Chief Georges-Ernest Gregoire told Survival International 'The caribou (reindeer) is central to our culture, our spiritual beliefs and to our society as hunters that have lived on our homeland, Nitassinan [Quebec-Labrador peninsula], for thousands of years.

Read more:  http://www.wildlifeextra.com/go/news/caribou-decline.html