By Susan Heath
Have you ever heard of a butcherbird? If you haven’t, you might be picturing a murderous bird wielding a bloody ax. If so you’re not off by much. A butcherbird, otherwise known as a Loggerhead Shrike, is a songbird with raptor-like tendencies. They are about the size of a cardinal, but are gray with black wings and tail and have a bandit’s black mask. Their head is large in comparison to their body size which is where the name Loggerhead comes from. Their bill has a sharp hook which aids in feeding on their preferred prey of insects, reptiles, amphibians, and small mammals.
Perhaps the most interesting thing about shrikes is their habit of impaling their prey. Because they catch large prey (relative to their small size) but lack the strong talons of a raptor, impaling their prey on a thorn or barb-wired fence allows them to rip it apart with their bill. Often, they will impale prey and save it for later dining. Shrikes love to hunt from power lines so if you keep an eye out, you might be able to see them there.
Although there are thirty species of shrikes worldwide, the Loggerhead Shrike is the only species that occurs exclusively in North America. The other North American shrike, the Northern Shrike, also occurs in Asia. The Loggerhead Shrike range extends across the entire U.S., south into Mexico and north into Canada. The more northerly birds are migratory while the more southern birds are resident. Here in Texas, we have both residents and migrants during the winter months (November – February).
Although Loggerhead Shrikes are common in Texas, they have exhibited steep population declines throughout most of their range and are now listed as endangered or threatened in many states, especially in the mid-Atlantic and Northeast. They would have become extirpated from Canada if there were not a captive breeding program that keeps the population going there.
The reasons for these declines are not well understood but may be linked to the use of pesticides in agriculture on the breeding grounds. They might also be affected during the nonbreeding season. How well a bird fares during the winter has a big impact on how their next breeding season goes. For example, if a bird struggles to stay well fed during the winter, when they arrive back on their breeding grounds they may not be fit to breed or raise young.
Here in Texas, we don’t know how the migrant shrikes that arrive in late October fit in with the resident shrikes that have permanent territories. Are the migrants pushed off into less desirable habitat? If so, that may be affecting their breeding attempts when they return north.
The Gulf Coast Bird Observatory and the Texas Mid-coast National Wildlife Refuge Complex have initiated a study funded by the National Fish and Wildlife Foundation to investigate the habitat affiliations of resident versus migrant shrikes during winter. We will be tracking shrikes for three winters to map their territories and analyze the habitat within them. Keep an eye out for shrikes with color bands or antennas when you’re checking those power lines! You might see one of our research subjects!
Photo caption: A Butcherbird scans its habitat from a high perch. Photo by Allen Timmer
