Majority of B.C. moose at risk from potentially deadly ticks
Ticks cause hair loss and drain blood, making it difficult for moose to survive cold winters
By Andrew Kurjata, CBC News Posted: Aug 15, 2016 2:13 PM PT
A new study indicates nearly two-thirds of moose in British Columbia are infected with a potentially deadly tick.
Michael Bridger led the study for the provincial Ministry of Forests, Land, and Natural Resources. He said though the ticks are not always fatal, they can cause severe problems.
"Each female [tick] in the winter can take up to two millilitres of blood, so if you had, say, thousands and thousands of female ticks on a moose then they could be losing upwards of ten, twenty, thirty, forty litres of blood over the course of a month or two," he said.
"That has some pretty clear implications for [the moose's] survival."
A closer look at the winter ticks affecting up to 61 per cent of the moose in British Columbia. (Serge Simoneau/Linda Brochu)
Bridger and his team recorded the rates of hair loss in moose, a trait associated with the winter ticks. From January 1 through to April 30, 2016, 61 per cent of moose observed had hair loss.
That number is up from 50 per cent in 2015, though Bridger cautions the increase does not necessarily mean more moose are infected.
He says ticks are naturally occurring, but it appears warmer weather may be affecting where and how many of them are found.
"We suspect with climate change we may be finding ticks in places that we haven't found them before, and the severity of the infestations may be increasing as well."
Most of the moose with ticks were seen in northern British Columbia. Seventy-three per cent of the moose observed in the Peace (northeast) region appeared to be infected, while the Skeena (northwest) and Omineca (Prince George) regions had infection rates of 56 and 53 per cent, respectively.
Bridger said the study is a continuation of the province's efforts to understand and manage British Columbia's declining moose population.
"Moose are an extremely important species in B.C., to First Nations, to local hunters, to guide outfitters and so on," he said. "So it's a species we definitely want to be focusing on right now."
The full 2016 report on the provincial moose winter tick surveillance program is available on the B.C. government's website.
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Excerpts from THE 2016 REPORT ON THE PROVINCIAL MOOSE WINTER TICK SURVEILLANCE PROGRAM
During times of moderate to severe tick infestations there can be many physiological and
behavioral implications towards moose including anemia, reduced visceral fat, decreased time spent
feeding, reduced growth in calves, increased energy expenditures in the form of restlessness and
scratching, and increased grooming resulting in damage to the winter hair coat (Samuel 1991, Samuel
2004, Franzmann and Schwartz 2007, Bergeron and Pekins 2014).
Many animals such as bison, elk, and
deer are considered "programmed" groomers; grooming on a regular basis in order to remove ticks
throughout the fall and winter (Samuel 2004).
Moose are considered to be "stimulus" groomers, spending
excessive amounts of time biting, licking, rubbing, and scratching (Samuel 1991) only when infested with
ticks in late-winter and early-spring, during the critical months of nutritional and energetic stress on
moose (Samuel 2004, Franzmann and Schwartz 2007).
Calves appear to be most susceptible to stresses
endured during this time due to their high energy demands and the effects of anemia (Addison et al.
1994). High levels of blood loss can severely affect nutrition and growth, particularly during the winter
months when the availability of proteins is limited (Addison et al. 1994, Samuel 2004).
The most noticeable effect of grooming is hair loss or breakage of guard hairs. Hair loss
commonly occurs on the neck, shoulders, upper mane and withers, and hind quarters. It is most noticeable
from mid-March through April when adult female ticks are engorging (Addison et al. 1979, Mooring and
Samuel 1999, Samuel 2004, Bergeron and Pekins 2014).
The extent of hair loss has been used as an
indicator of tick infestation severity in individual moose, where greater amounts of hair loss suggest a
higher tick burden (Samuel 1989, Pybus 1999, Samuel 2004, Franzmann and Schwartz 2007, Bergeron
and Pekins 2014). Thus, by documenting the extent of hair loss it is possible to estimate tick infestation
severity in moose populations on an annual basis (Bridger 2015).
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