Out for a walk through a farmer’s field, you encounter a grisly scene: a mouse impaled on the thorn of a Hawthorne tree. What you’ve stumbled upon is the larder of a “Butcher Bird”, also known as the Eastern Loggerhead Shrike (Lanius ludovicianus migrans).
The Eastern Loggerhead Shrike is a medium sized songbird, about the size of an American Robin (Turdus migratorius). The name “loggerhead” comes from its disproportionately large, or “logger” head. The bird’s most striking feature is a broad black facial mask which covers and extends above its eyes. Eastern Loggerhead Shrikes are predatory songbirds. Shrikes use their hooked bills to dispatch prey such as insects, mice, frogs, and snakes. Hunting from perches in treetops or on wires, shrikes are known for impaling prey on thorns or barbed wire. Shrikes do not have the strong grasping feet and talons of a raptor, and therefore shrikes need to impale their prey. Once the prey is impaled, shrikes use their beak to tear off bite-size chunks.
Unfortunately, your chances of stumbling across a shrike’s impaled dinner are slim in our province. In 2016, only nineteen pairs existed in the wild in Ontario. Eastern Loggerhead Shrike prefer open short grassland with areas of trees and shrubs for nesting, thorn trees for impaling, and exposed perches for hunting. Cattle ranching can be beneficial to this bird because cows keep the grass short, which makes foraging easier for shrikes. Eastern Loggerhead Shrikes used to live as far west as Manitoba, to New Brunswick in the east, and south to North Carolina, Maryland and northern Texas. While the populations in the southern part of the species’ range remain largely unchanged, the species is now largely extirpated in many parts of the central and northern part of its range. In Canada, the species is found in isolated areas of Manitoba and in Ontario, most notably the Carden and Napanee limestone plains. The species last nested in the Maritimes in 1972 and in Quebec in 1995.
The reasons behind the population decline are not entirely well understood. The loss and fragmentation of their short grassland habitat has always been seen as a threat to this species; however, recent surveys suggest that there is available habitat in both Ontario and Quebec that could support more breeding pairs than currently exist in the wild. Roads and traffic are a threat to this species. Shrikes often perch on fences or wires near roadsides and when they swoop low to pursue prey they run the risk of being struck by vehicles. The use of pesticides may also play a role in their decline. It is suspected that the biggest cause of decline in shrike populations seems to lie either on their migratory routes or on their overwintering grounds. Research is currently being conducted on this factor.
One of the things that is known about this species is that captive breeding efforts play a major role in the maintenance and recovery of this bird in the wild. According to Parks Canada, captive breeding is the process of taking a “limited number of source animals…from large, wild populations and bred in captivity. Offspring are strategically released into wild areas where they will have the greatest conservation value and the optimum chances for success”. In 1997, when only 18 pairs could be found in the wild in Ontario, Environment Canada established a captive population to ensure that the unique genetic material of the Canadian birds would be preserved. This project is now managed by Wildlife Preservation Canada, with main project partners including the Toronto Zoo, African Lion Safari and the Mountsberg Conservation Area. Mountsberg’s shrike breeding facility opened in 2011 with 12 birds moving in for winter housing, and our first breeding season was in spring 2012. Since then, 80 young shrikes have been transferred from our breeding centre to release sites in Carden and Napanne, and from there have been released to supplement the wild population. Some of these birds have since returned to Ontario and are now part of the wild breeding population. As of the 2016 breeding season, approximately 20% of all breeding birds spotted in the wild in Ontario were birds released from the conservation breeding program in previous years. These birds paired successfully with wild mates and contributed significantly to the number of young in the wild population.
At the time of writing, staff at Mountsberg are anxiously awaiting the hatch of the first babies of the season. If all goes well, up to 25 young birds should leave the breeding facility in July and August to bolster the wild population. It is hoped that we will see more shrike snacks on thorns in the future.
 Source: https://www.pc.gc.ca/en/pn-np/ab/banff/decouvrir-discover/faune-wildlife/caribou/captive-captive
Last modified: May 31, 2017