“You can’t catch a wild shrike twice”: CAZA facilities work together to repopulate Canadian migratory songbird
Posted onOctober 3, 2022by|, , ,
Dr. Amy Chabot is the Research & Conservation Program Coordinator for African Lion Safari as well as the co-founder of Canadian Species Initiative (CSI). We recently had a conversation with her about the ongoing repopulation of one of Canada’s most endangered songbirds: the eastern loggerhead shrike.
According to Amy, the conservation needs of many Canadian species are often overlooked. Unlike well-known animals whose populations are vulnerable (rhino or polar bears, for instance), there are numerous Canadian species whose numbers are declining. There is just as big a need for conservation work in our own backyard.
That’s part of what Canadian Species Initiative is about: identifying Canadian species at risk who can benefit from conservation plans with both in-situ and ex-situ parts (as laid out by the International Union for the Conservation of Nature’s One Plan Approach), and creating a concrete plan for how CAZA facilities can assist to ensure species recovery.
The loggerhead shrike is part of our collective Canadian natural heritage, particularly in Ontario. They are believed to have been here a very long time – since after glaciation – and have evolved with alvar habitat around the Great Lakes. In the past, eastern loggerhead shrike resided from Manitoba to New Brunswick. Now, however, there are only 21 breeding pairs, and those are restricted to two isolated pockets in Ontario: the limestone plains of Carden and Napanee.
Amy’s story with loggerhead shrike began over 30 years ago. In 1991, the species was assessed as endangered by the Committee on the Status of Wildlife in Canada (COSEWIC), and by 1997, there were just over a dozen pair in Ontario and Quebec. In 2000, an experimental conservation breeding program was established, which has been managed by Wildlife Preservation Canada since 2003. The ex-situ breeding program is a cornerstone of the species recovery strategy, whereby juveniles bred at CAZA facilities are released back into the wild to boost the population. The eastern loggerhead shrike recovery team, in coordination with other partners, initially captured a colony of 40 nestlings from wild pairs in Ontario.
Since then, 1,300 juvenile shrike have successfully been released in Ontario. Today, up to 36% of shrike spotted in the wild are birds released from the program. Moreover, many of these migratory birds return year after year: “In 2012, for example, a six-year-old female released in 2006 returned to pair with a wild male — solid evidence that the field breeding and release techniques are working” (WPC). This is the first time a migratory songbird has been successfully repopulated.
There is more to the program than just breed and release. While maintaining a healthy population of shrike, participants are also working toward finding the causes of vulnerability and ensuring that the environment is safe and conducive to species repopulation. The ex-situ population has been instrumental to these efforts – unlike wild shrike, that you can only catch once (they’re very smart!), birds at CAZA facilities can be closely monitored. This helps with assessing, for example, the impact of West Nile Virus infection and environmental conditions on migratory behaviour.
Moreover, research has been conducted around habitat stewardship for shrike, who prefer limestone plains that are often found on private land. Wildlife Preservation Canada has worked closely with landowners to protect and enhance shrike habitat on their property, ensuring they have suitable nesting sites and hunting grounds.
The program also continues to track and monitor released birds to gather clues about their migratory patterns. It appears that the cause for the decline of this species is occurring outside of Canada, so a partnership has been formed with U.S. conservation partners in identifying routes and confronting threats during migration.