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Declining Vancouver Island cougar populations linked to wolves

Large carnivore specialist says human development still plays biggest role on cougar numbers
Wildlife advocate Gary Schroyen captured this picture of a one-year-old cougar in the Sooke Hills using a homemade trip camera. Schroyen presents Animal Signs: The Essence of Animal Communication on Nov. 30. (Gary Schroyen)

Nature always has a way of coming into balance.

For a time, deer and cougars roamed Vancouver Island in relatively dense populations. Cougar populations are closely interconnected with their prey, as deer provide a vital source of food for the carnivores.

Up until the late 1970s, deer populations on Vancouver Island were spiking, but began to decline through the ‘90s, around the same time wolves began to recolonize the land.

Provincial large carnivore specialist Garth Mowat speculates this factor could have also impacted cougar density on the Island, as they had less to eat, and wolves will tend to eat some cougar cubs. Mowat highlighted that the Sunshine Coast, a similar habitat to the Island, is home to both wolves and cougars, and has never seen the highs in deer populations that the Island saw in the 1980s.

“We have nowhere near as good of data on cougars here, as compared to somewhere like Yellowstone, but I think it is fair to say that as wolves recovered on Vancouver Island there was some competition with cougars,” said Mowat. “The trend in cougar numbers is down to something like a third of what it was before. My guess is that it’s a competitive effect with wolves.”

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Mowat said as more wolves started appearing and deer populations declined, more cougars found themselves with inadequate food and were getting into conflicts with people. Since the 1990s, deer density has not recovered compared to where it was.

“Now populations may have balanced off. I haven’t heard about cougars attacking people on Vancouver Island for years,” said Mowat. “The attacks in the ‘80s and ‘90s could have been more food driven on the cougars’ part.”

Cougars need a territory of about 10 square kilometres, and during breeding season a male’s territory may increase two or three times in size while they search for a mate.

“They don’t just wander randomly, they are very territorial,” said Mowat. “Adult males will kill or injure young males that wander through searching for their own territory. Females have a home range, but you don’t hear as much about them trying to dissuade other cougars from entering their territory.”

Cougars are a solitairy, nocturnal animal who eat almost any prey they can capture. Most of the Island’s population appear reddish brown in colour and a fully grown male will weigh about 70 kg. Mowat said cougars, as well as other predators, play an important role in an ecosystem, as they limit herbivore foraging on plants and young trees, and control the smaller mammal population.

Mowat noted that the biggest impact on cougar populations overall, however, has been due to human development.

“A parking lot is not a good habitat for virtually any animal,” said Mowat. “We need to think about better ways of living together with cougars, because when there is a conflict with a cougar, it usually ends up being killed.”

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Up until the late 1970’s, deer populations on Vancouver Island were spiking, but began to decline through the 90’s, around the same time wolves began to recolonize the land. Provincial Large Carnivore Specialist Garth Mowat speculates this factor could have impacted cougar density on the Island. (Black Press file photo: Supplied by Conservation Northwest)

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