Lanius ludovicianus migrans
In 2003, Wildlife Preservation Canada was invited by Environment Canada to lead the recovery effort for this critically endangered songbird, which numbers fewer than thirty breeding pairs in a few isolated spots in southern Ontario. WPC developed an effective in situ captive breeding and release program, and within a few years, captive-bred birds were returning from migration and pairing with wild birds to breed. This achievement was a first for a migratory songbird captive-breeding effort and brought international acclaim to the program.
Since 2003, the number of breeding pairs in the wild population has remained relatively consistent from year to year, although we have seen some ups and downs during this time. It is believed that poor winter weather in the southern U.S. has a negative effect on the number of birds returning to breeding grounds in the spring. In response, we are redoubling our efforts to track the specific migratory routes and wintering grounds used by Ontario shrikes. Little is known about their migrating and wintering behaviour, but it appears that the biggest causes of the shrikes’ decline are occurring outside of Canada. With this information in hand we hope to partner with U.S. conservationists to reverse the declines. In the meantime, our captive breeding program remains the species’ only hope for survival.
Named for its disproportionately large, or “logger” head, the eastern loggerhead shrike is a medium-sized grey and white songbird, slightly smaller than a robin with black on the wings and tail and a black raccoon-like “mask” across its eyes. Along with its larger cousin, the northern shrike, they are the only truly predatory songbird, using their hooked bills to dispatch mice, frogs, grasshoppers, beetles and other small prey. Lacking strong talons or claws for grasping their prey, shrikes will impale their dead prey on the thorns of shrubs or barbed wire to help them tear their meal into manageable pieces.
Most eastern loggerhead shrikes winter in the southeastern United States and migrate to Canada in April for the breeding season. Females lay an average four to six eggs, which they incubate while the males bring them food. The eggs hatch 16-18 days after laying, and both parents feed the young. Young shrikes have bright orange, featherless skin and yellow beaks and talons. After about 18 days they are ready to leave the nest, although the young continue to depend on their parents for another three to five weeks as they learn to fly, forage and become independent.
Shrikes prefer flat, open areas of short grassland with scattered trees and shrubs for nesting and hunting. Shrikes can often be found in alvars, unique habitats consisting of shallow soils over limestone bedrock, resulting in naturally short grasslands. Elsewhere, cattle ranching and pastures are important land use types, helping to keep the grass short for foraging.
Distribution and Population Size
Originally the range of the eastern loggerhead shrike extended from Manitoba to New Brunswick and as far south as northeastern Texas, western North Carolina and Maryland. Today, eastern loggerhead shrikes are restricted to several small isolated pockets in Ontario. This includes the Carden and Napanee limestone plains, where breeding pairs are consistently located, and the Smiths Falls plain, the Pembroke and Renfrew areas, Grey and Bruce Counties on the Bruce Peninsula, and Manitoulin Island, where individuals or breeding pairs are occasionally observed. They are no longer present in the Maritimes, and breeding pairs are infrequently found in Manitoba. In 2010, the first breeding pair in 15 years was found in western Quebec. It is believed there are only 100 pairs remaining in North America. In 2013, 24 wild pairs were found in Canada, all of those in Ontario.
Threats to Survival
The causes of the persistent decline in eastern loggerhead shrike populations are poorly understood. The greatest threat to the eastern loggerhead shrike has historically been the loss and fragmentation of the short grassland they depend on. This is due to natural succession and changes in agricultural land use, particularly the conversion of pastures and hayfields to grow crops, which involves removing the hedgerows, shrubs and trees that are essential to the shrike’s lifestyle. Another potentially serious problem is motor vehicles. Shrikes often perch on fences and utility lines near roadways, and sometimes collide with passing cars and trucks. The use of pesticides may also be a factor. Lastly, and perhaps most importantly, conditions or changes to their migration routes and wintering grounds may be having an effect on the number of birds that are able to return to breeding grounds in the spring.
The eastern loggerhead shrike was listed as endangered by the Committee on the Status of Endangered Wildlife in Canada in 1991. A Loggerhead Shrike Recovery Team was formed in 1992, and in 1996 the Team divided into a Western Loggerhead Shrike Recovery Team (for the threatened western subspecies), and an Eastern Loggerhead Shrike Recovery Team (for the endangered eastern subspecies). WPC’s recovery effort consists of:
- Conducting annual surveys and monitoring the population size and breeding success of wild shrikes.
- Banding birds and asking birders and other members of the public to report sightings to determine an accurate population size.
- Breeding birds in captivity to protect the genetic diversity of the species and releasing their young into the wild to boost the wild population.
- Conducting genetic studies to learn more about shrike population dynamics.
- Contacting landowners and helping them protect and enhance shrike habitat.
- Working with agricultural associations, aggregate producers, conservation and naturalist associations and many others to protect and improve shrike habitat.
- Attaching geolocator dataloggers to captive-bred birds released into the wild to determine their migration routes and wintering grounds.
- Liaising with American counterparts to establish a North America-wide recovery effort.
Our efforts are paying off. We are learning more about the threats to the wild population, and thousands of acres of habitat have been restored or improved. The program has also seen a number of successes to date. Since 2006 the number of shrikes hatched in captivity each season has ranged from 77 to well over 100, with the majority of fledglings being released into the wild. In 2008 we had eight of those captive-born birds return to the nesting grounds in Ontario, which is our highest number of returns in a season so far. 2010 was also a particularly exciting year with the return of a four-year-old captive-bred bird, the confirmation of the same captive-bred bird returning to the same territory in consecutive years, and two captive-bred birds pairing and attempting to breed in the wild. In 2012, a six year old captive-born female released in 2006 returned to pair with a wild male – solid evidence that the field breeding and release techniques are working. Most recently, we received confirmation that our hacking efforts were successful when five fledglings hacked in 2012 returned to the breeding grounds in 2013. Hacking is a practice in which captive-born juveniles from one location are transported to release enclosures at another location containing typical shrike habitat; birds are given several weeks to adjust to their new surroundings before being released. Our success with hacking creates the potential to increase the breeding capacity of the captive population as we welcome more partner facilities to the program.
We’re also excited about our geolocator study. These tiny data loggers record sunrise and sunset times which can be turned into geographic position information. This new research promises to reveal where shrikes spend the winter and what routes they take to get there. With that information, we’ll be able to tackle what may be the largest cause of shrike declines. For continuing updates, see our field reports (right) and our blog.
What you can do to help
- Make a contribution today towards WPC’s Eastern Loggerhead Shrike recovery activities.
- If you are a landowner within the traditional breeding areas of the eastern loggerhead shrike (in Manitoba, West St. Paul, the Red River Plain and the Interlakes; in Ontario, the Carden, Napanee and Smith Falls limestone plains, Grey and Bruce Counties, and Manitoulin Island; and in Quebec, the Outaouais), here’s how you can help maintain or improve habitat for shrikes:
- Maintain existing pastureland and expand, if possible.
- Maintain and plant trees and shrubs at the edges of pastures and fields.
- Leave the odd snag (dead tree) standing.
- Let cattle graze.
- Avoid using pesticides on your land.
- Avoid approaching nest trees, breeding birds and their young between April and the end of August.
- Report all sightings of eastern loggerhead shrikes to the recovery program’s toll-free number, 1-800-956-6608, or contact us by email at email@example.com.
Find out more about recent reports of shrike sightings!
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