Wildlife Preservation Canada first became involved in burrowing owl recovery in Saskatchewan in 1995. Between 1995 and 2002, we established a small conservation breeding colony in the province and experimented with different release methods. This led to the development of a novel “soft-release” technique that showed the greatest success. The method involves putting pairs of young owls from the conservation breeding program into field enclosures and releasing them after they have laid their first clutch of eggs. We also investigated ways to enhance the survival of wild owls, such as providing supplemental food and installing nest boxes that deter predators.
Meanwhile, in British Columbia the Burrowing Owl Recovery Team and Burrowing Owl Conservation Society of B.C. were attempting to reintroduce burrowing owls, which had disappeared from the province in the 1980s. Owls from a conservation breeding program had been released in the province since 1992 using a hard-release technique in which pairs were released directly from artificial burrows. However, birds often left the site soon after release, and migratory returns were extremely low.
In 2005-2006, we funded research in B.C. to compare and evaluate the traditional hard-release technique against the soft-release technique we had developed in Saskatchewan. The two techniques were implemented at the same time and evaluated in terms of number of birds remaining at the site after release, their survival, the number of young produced and the number returning to breeding grounds the following year. Since then we’ve continued to support the Burrowing Owl Conservation Society of BC’s reintroduction program.
Fifty owls returned to B.C. breeding grounds in 2015 — a record for the program — and the species has been downlisted from Extirpated to Endangered. Release efforts in B.C. are also helping to support other burrowing owl populations. A female hatched in the south Okanagan in 2014 was found nesting in Umatilla, Oregon, in 2015 and bred there again in 2016.
The soft-release technique we developed is credited as a key factor in increasing the number of owls returning to breed each year. Releases in Saskatchewan have helped to stabilize the population there, and if the current trend continues in B.C., we will have successfully re-established burrowing owls in this province. Experts recommend using the soft-release technique for burrowing owl reintroductions where they are required elsewhere in North America, and the methods may be more broadly applicable to other species.
Mitchell, A., T. Wellicome, D. Brodie et K. M. Cheng. 2011. Captive-reared burrowing owls show higher site-affinity, survival, and reproductive performance when reintroduced using a soft-release. Conservation Biology 144(5): 1382-1391. doi:10.1016/j.biocon.2010.12.019
Mitchell, A. 2000. The effects of release techniques on the reproductive performance and post-fledging juvenile survival of captive-bred Western Burrowing Owls (Athene cunicularia hypugaea) in the Nicola Valley, British Columbia. (MSc Thesis) Victoria: The University of Victoria, 83 p.
After completing her M.Sc. research on reintroduction techniques for burrowing owls in B.C., Aimee Mitchell continued to work in the program. Today she serves as science director of the Burrowing Owl Conservation Society of BC and is a member of the recovery team for this species.
The Burrowing Owl Conservation Society of BC is a non-profit society run exclusively by volunteers who are committed to returning self-sustaining populations of burrowing owls to B.C. grasslands.
- Leon Judah Blackmore Foundation