Wilder Institute/Calgary Zoo releases 100th burrowing owl

Last week, in a large open field near Suffield, Alta., a team from the Wilder Institute/Calgary Zoo celebrated a conservation victory.

They released their 100th burrowing owl — an endangered species found on the Prairies that the group has worked to protect and rehabilitate for seven years.

After the bird was set free, the team released another 19 owls, bringing their total up to 119.

"It takes a lot of work over many years. And we've learned something new from each additional owl that we release," said Graham Dixon-MacCallum, conservation research population ecologist with the zoo.

"So every one of them counts, which is why 100 is such an exciting milestone."

The zoo began its conservation efforts with burrowing owls — a small, long-legged species — in 2016 using a process called head-starting.

In late summer, they remove the youngest owl from a nest, which is the least likely to survive. It's brought to a facility southeast of Strathmore, Alta., where it receives special care over the winter.

In the wild, the youngest owlets have only about a two to three per cent chance of survival, the zoo says.

"We're releasing them as adults the following spring, so that we help them kind of skip that first winter migration, which is a time of really high mortality," Dixon-MacCallum said.

LISTEN | Dixon-MacCallum explains what it's like to release the owls:

It's unclear how many burrowing owls are currently in the wild in Canada, but their population has been in steady decline for the last four decades, according to a 2017 report from the Committee on the Status of Endangered Wildlife in Canada.

"Burrowing owls were once a common element of the landscape in the Prairies and southern interior of British Columbia," it reads.

"They are now rare throughout their Canadian range."

Endangered species

Although they're called 'burrowing' owls, the birds don't actually dig the burrows themselves. 

Dixon-MacCallum says one of the factors leading to the species' decline is a reduction in the number of animals who dig those holes. More extreme weather during migration, habitat loss and changes to predation also play a role, he said.

"It's a really different Prairie out there than it would have been a century ago or more."

The burrowing owls captured by the zoo are released in breeding pairs each spring. The owls are initially placed into an artificial burrow filled with a supply of mice, which helps them to reacclimatize to their surroundings. 

The hope is for the owls to breed their own owlets the following year. So far, they've had an 80 per cent success rate, with pairs producing five to six more owlets each, Dixon-MacCallum said.

The zoo monitors some of the owls through ankle bracelets. Other adult owls are equipped with tracking devices to help researchers determine how many of the birds are returning after winter migration.

Dixon-MacCallum says it's not clear what would happen if the burrowing owl became extinct, but he believes every species has intrinsic value.

"It's sometimes hard to articulate, I think, but when we talk about a whole species, I think it's hard for me to picture how they don't matter, more so than why they do."