One of our summer students from last year, Nate, has written a great series on grassland birds for our blog! Nate joined myself (Amanda) on our grassland bird surveys in southwestern Manitoba and has first-hand experience surveying for these interesting birds. So without further ado – watch out for the shrike!
Nicknamed the “butcher bird” the loggerhead shrike (Lanius ludovicianus) is infamous for it’s gruesome feeding habits. the scientific name Lanius Comes from the old Latin word for butcher. Physically, this bird is a far cry from a raptor, so in lieu of sharp talons for killing prey, the shrike bites the nape of the animal and severs the spinal cord, and then impales its prey on anything sharp enough to skewer a meal. Diet ranges from insects and worms to small mammals and other songbirds. Barbed wire is a favourite “impale site”, but hawthorns, rose bushes and even cactus can be used. Impaled prey can also be used to mark territory and can be stored as food caches. The savagery of Shrikes has been documented in ancient folklore as well as modern literature.
Shrikes are categorized as robin sized but slightly larger. There are different species of shrike with the closely related Northern Shrike bearing most similarities. The Loggerhead Shrike is smaller and darker than the Northern Shrike with a shorter and smaller hooked bill. In flight the Loggerhead Shrike is similar to Northern Mockingbird but distinguished by larger head, quicker wing beats and smaller white wing patch. The adult has a broad, thick black mask that goes from behind the eye and continues thinly over top of bill. The song of the Loggerhead Shrike is generally a collection of sharp, precise mechanical two-syllable phrases, each phrase repeated at short intervals. Calls include scolding, grinding, or ringing sounds with a harsh ‘shack-shack’.
Loggerhead Shrikes are found in the Parkland and Grassland regions, where they make use of sagebrush stands, wooded agricultural areas, grazed and tall grass prairies. The Shrike depends on its habitat for impaling its prey. Barbed wire fences and thorn brushes are essential to its choice of habitat. Due to these objects being near grid roads and highways, vehicular collision has been documented for 29% of mortalities according to a fall and winter survey in Virginia; 1989. For example, the San Clemente Loggerhead Shrike is endangered due to loss of Catalina Cherry trees and coastal sage scrub. This vegetation is being replaced with exotics and annual grasslands, eliminating natural habitat for this bird.
The Loggerhead Shrike tends to nest earlier than other songbirds, with some populations establishing territory in late February. Both sexes inspect multiple nest sites before settling down. They often nest in trees with thorns but will move to deciduous trees later in the season. Nests are an open-cup design with twigs, bark, and roots for structure of the nest. Inside, it is lined with soft materials such as moss, feathers, and the fur of mammals. Females lay a clutch of 4-7 grayish, oval eggs and the female Loggerhead Shrike incubates the eggs while the male feeds her. Incubation takes 15-17 days, and hatching occurs over 36 hours. At 20-25 days of age the young will practice impaling by picking up an object with its beak and tapping it on a branch or perch.
The Loggerhead Shrike ranges widely across the central U.S.A and northwards into the Prairie and Parkland regions of Canada. This is where most of the breeding occurs. Populations winter through the southern United States, and south through Mexico. As of May 2014, COSEWIC declared that the Loggerhead Shrike to be threatened for the provinces of Alberta, Saskatchewan, and Manitoba, largely due to the effects of habitat loss and pesticide residues. The main causes of habitat loss are thought to be urbanization of farmlands and conversion to thicker woodlands. These birds are a rare sight in the province with your best bet of finding a Loggerhead Shrike in the southwest grasslands of Manitoba.
-Nathan (Nature Nate) Entz