February 1, 2019 Calgary Zoo

Tails from the Field: Giving Burrowing Owls in Alberta a Boost

Written by Alyssa Friesen, Conservation Linkage Associate

From the rise, the prairie stretches out to meet the darkening sky. Barbed wire fences and power lines intersect the plains. Graham Dixon-MacCallum, Conservation Research Associate, holds the receiver’s antennae steady in the wind, waiting for a signal from the satellite transmitter. The signals arrive minutes apart. We slowly hone in on the location of the transmitter, using the strength and direction of the signal as a guide.

Weighing only 6 grams, these miniscule transmitters are helping researchers at the Calgary Zoo track the migration routes of burrowing owls. Each year, these tiny grassland birds make an incredible trek as they migrate from Canada to Mexico and the southern United States. Many owls don’t return from this journey, but their fate is unclear.

The Calgary Zoo, together with Environment and Climate Change Canada, Canadian Wildlife Service and Alberta Environment and Parks, is piloting an innovative project to give the endangered burrowing owl population a boost. We are using a conservation tool called head-starting which involves caring for young owls in captivity and releasing them when they have a better chance of succeeding in the wild.

Burrowing owls usually lay about nine eggs, some of which hatch days apart. In the wild, the youngest owlets in a nest don’t often survive. To give these owls a head-start, we collect them in the summer and care for them at the Calgary Zoo over the winter. They are released the following spring, wearing satellite transmitter backpacks that record their location every couple of days. Collecting this movement data allows researchers to map migration routes and understand the challenges burrowing owls face as they travel to their winter territories.

As the sun sets, we stop by the truck to refuel on chocolate milk and pick up our headlamps. Powered with a small solar panel, the satellite transmitter only emits signals for 10 hours before it needs to recharge. Knowing that we only have a short window of time to find the transmitter, we decide to continue searching in the dark. We suspect that we won’t find a burrowing owl – the activity sensor hasn’t recorded movement in a few days, but we need to find the transmitter to be sure.

The signal begins to get stronger. We slow down to search for signs of a burrowing owl. Our headlamps cast shadows and every blade of grass looks like the antennae of a transmitter. Graham notices a pile of feathers among the grasses. Close by, we find the transmitter, a silver bird band and more feathers. The shafts of the feathers are splintered, which tells us that a mammal, likely a badger or coyote, probably caught this burrowing owl.

“Predation is pretty common this time of year in wild populations,” says Graham. “Burrowing owls are starting to fly further from their burrows as they prepare for migration. This is just one of the challenges our head-started owls will face in the wild.”

Severe weather, decreased prey availability, lack of burrow habitat and vehicle collisions are potential threats that have been identified for burrowing owls. Transmitter data that we collect from our head-started owls will help us understand how these potential threats affect them and how we can better aid in the survival of this endangered species.

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