Alisa Samuelson is this season’s biologist in the Carden, ON area with the Eastern Loggerhead Shrike Recovery Team. Alisa was the seasonal Carden area biologist in 2017, and returns to WPC after spending a few years travelling across North America working on various other monitoring and recovery teams for endangered bird species.

Happy belated shrike breeding season!  I am happy to be in the Carden Alvar in central Ontario for another season. We are off to a very late start.  Surveys for this endangered songbird ideally begin in April and we just got started the first week of June, but the shrike team is up and running with the 2020 theme proposed by lead biologist, Hazel Wheeler, “Better late than never!” Phase 1 of lifting Covid-19 restrictions in Ontario have allowed for biological research activities to resume with proper safety precautions, and we are all grateful that this breeding season will not be missed entirely.

My fascination with loggerhead shrikes, sparked in Carden in 2017, has grown to a bit of an obsession with this tenacious species. This has resulted in me terrifying a coworker at another field job by slamming on the truck brakes and yelling “SHRIKE!” at my first sighting of the spring, and it also led me to the San Clemente Island naval base in California to work with another endangered subspecies of loggerhead shrike.

The San Clemente Loggerhead Shrike recovery project is similar to WPC’s in many ways, as it also has wild shrike monitoring and conservation breeding and release components with collaboration between zoos, the government, and non-profit organizations; however, these subspecies of loggerhead shrikes are very different. After thinking I was familiar with loggerhead shrikes from working with the eastern subspecies, I was shocked to experience the dramatically different environment that the San Clemente species inhabit.

Two quite different shrike habitats

Surveying for loggerhead shrikes in the Carden Alvar, above, and a slightly different view, below, surveying a shrike nest on the far canyon slope on San Clemente Island.

San Clemente is the southernmost of California’s Channel Islands with an area of less than 150 square km and a maximum elevation of nearly 600m.  The dramatically different climate off the coast of San Diego compared to southern Ontario is one key factor in why these subspecies are so different.

What are the main differences between these subspecies?

Breeding season timing

While breeding season in Ontario begins in May, on San Clemente Island some shrikes begin pairing up in January and the more successful pairs have already had their first brood of chicks leave the nest by the time breeding begins in Ontario.

Migratory habits 

All seven subspecies of loggerhead shrikes can be grouped into one of two broad categories: short-distance migrants (“short” being less than intercontinental long-distance migrants like shorebirds) or year-round residents.  Eastern loggerhead shrikes are migratory, spending their winters in the east-central US and breeding in southern Ontario where there is less competition for food.  San Clemente Loggerhead Shrikes are year-round residents, endemic (found exclusively in one location) to the island.  This key difference results in several variances between these subspecies, the most notable of which are their behavior and the conservation impacts of these migratory strategies.

Can you spot the shrike?

It is important to have an eagle eye when you are out surveying for shrike. Can you see the loggerhead shrike hunting on the rocks of this canyon on San Clemente Island?

Comment on WPC’s social media if you are interested in reading more about the differences between shrike subspecies. My greatest challenge in writing about loggerhead shrikes is stopping before I write a giant manuscript! In fact, this challenge is so insurmountable that I have begun a PhD at Queen’s University researching the role of genetics in migratory urge of loggerhead shrike, so you will likely continue to see intermittent updates from me for several years to come. Thank you for reading and your interest in endangered species conservation.

Alisa Samuelson