Moose on the Loose

For several evenings we’ve been treated to a visit by two young bull moose. They are possibly last year’s calves, out on their own. Or maybe they’re just a couple of teenagers, hanging out together.

They were curious about our deck. One nibbled the edge but decided it wasn’t worth the bite.  Then it was back to what they came for—tender willow leaves.

The bumps on their foreheads? This year’s antlers in the making. The skin, known as velvet, provides blood and nutrients to the growing bone beneath.

Young bull moose dining on willows

Ghost Moose

I discovered this bull moose among a stand of cottonwoods, nibbling willow twigs. This is a ghost moose — so-called not for his ability to blend into his surroundings but for the damage imposed by moose ticks.

From a distance he seemed okay. You might not notice the problem but if you’ve seen it before you recognize the symptoms — scruffy hide, mangy looking, malnourished, slow-moving — a general something’s-not-right look about him.

Tick-infested bull moose

Although moose ticks latch onto other ungulates including white-tailed deer and bison, moose are the victims of choice and suffer the most. Young ticks climb onto the moose in fall where they remain all winter. Come spring the blood-filled females drop to the ground to lay their eggs.

Moose are relatively helpless when it comes to removing ticks. Scratching and rubbing remove some, but doing that breaks off the dark hairs of its winter coat, leaving only the white base growing close to the skin. If enough of the winter coat is rubbed away the moose can appear white as a ghost.

This moose has rubbed his chest almost bare and scraped hair off his shoulders. Patches of white hair are visible behind that.

Chest skin rubbed bare

He’s not badly off according to British Columbia’s Wildlife Health Program. He’s suffering from “mild hair loss” affecting only about 5-25% of his winter hair.

Tick-infested bull moose

Moose ticks (also known as winter ticks) can bring the strongest moose to its knees and shove it into a drawn-out painful death.

Tick counts on moose can reach astonishing numbers — 50,000 or more ticks per animal. One paper suggested counts as high as 75,000. Such loads have severe consequences — not the least of which is anemia from loss of huge amounts of blood. Moose also spend more and more time “grooming” instead of eating. If enough hair is rubbed off hypothermia may set in.

Heavy tick loads also affect ongoing health. Young moose calves who come through their first winter with a load of ticks may simply die. Older animals go into the next breeding season weak and rundown, leading to less healthy calves.

A vicious circle. And one not easily broken. Depending on where the moose live — from BC or Alberta to Maine or Minnesota — other factors come into play. A series of dry summers and warm winters in Alberta during the 1990s lead to about a 30% die-off in certain populations during the winter of 1998-99. In Maine the problem is compounded by lungworms.

Moose and ticks have lived together a long time but recent changes — including climate change — may be affecting the moose’s ability to cope with increasingly heavy parasite loads.

Note: Some provinces and states run submit-a-tick programs to monitor the types of ticks, especially those carrying disease such as Lyme disease. If you live in Alberta you can submit ticks here.

Moose   Alces alces
Winter/Moose tick   Dermacentor albipictus