The Nature Writers of Texas

The best nature writing from the newspaper, magazine, blog and book authors of the Lone Star State . . .

Sunday, September 26, 2004

Loggerhead Shrikes are Fascinating Songbirds
by Ro Wauer

This black-and-white songbird is unique in several ways. It is one of the few true songbirds that acts more like a raptor than a songbird. That is because it captures its prey with its strong, hooked bill, and instead of eating it on site, it will often impale its prey on a sharp point and eat it there. As a songbird, a shrike does not possess the strong feet of a raptor to tear apart its prey, so it impales its catch instead. In fact, loggerheads are know for impaling several individual catches on barbed wire, yucca leaves, or other sharp objects, like decorating a Christmas tree. Researchers claim that female shrikes are more attracted to males that have numerous "scalps," proof of their hunting ability. During the breeding season, male shrikes with the greater number of impaled prey are the most successful breeders.

Small prey is often swallowed whole, and their feathers and bones are later regurgitated, but larger prey are carried to favorite sites and impaled where they can be eaten at their leisure. Shrikes actually store food for later use in this way. But lots of other birds store food, whether it is an acorn woodpecker that stores acorns in crevices or acorn-sized holes drilling in snags or utility poles, jays that hide their extra food in crevices, or various other birds that hide food in grass or bury it in the ground. The American kestrel is a good example of one that caches food in grass clumps. The Clark's nutcracker stores its extra food supply in the ground. Researchers tell us that approximately 75 percent of a kestrel's cache are found later and utilized. The Clark's nutcracker, a large bird of the Western mountains, hides its extra food in the ground, often in several locations. How do they remember where that food is hidden? When researchers move adjacent rocks and shrubs around, the birds become confused and cannot find their cache.

As many as 72 species of shrikes are known worldwide, but only two occur in North America, the northern shrike of the boreal forests and the loggerhead shrike of the central and southern states. All are small to medium-sized birds, 7 to 10 inches long, with large, broad heads and stout bills that are strongly hooked and notched at the tip. The notched bill is very similar to that of falcons, unlike other songbirds. It includes a toothlike structure on the cutting edge of the upper mandible that corresponds to a notch on the lower mandible. These "teeth" are important in the shrike's killing ability. It is able to kill prey with a series of sharp bites with its strong hooked bill, which can sever neck vertebrates of its prey.

Prey can range from tiny insects to birds larger that a shrike, such a mockingbirds and jays. Small mammals, lizards, and small snakes, as well as a wide variety of invertebrates are also taken. Prey not swallowed immediately are impaled on favorite perches. Most are impaled with the head up and body hanging down. This method of impaling has given the loggerhead shrike the name "butcher bird."

Although a few loggerheads are full time residents in South Texas, many more are present during the winter months when more northern birds move into our area. Already the "winter Texan" shrikes are arriving. And their harsh trill or rattle call can be heard at almost any open area, even in vacant lots inside the city. They are easily identified by their stocky, short-necked appearance, short wings, and black-and-white colors: black wings, tail, and mask; gray back; and white underparts and wing patch evident in flight. Its black mask makes it look like a little avian bandit. And it flies in a straight line with fast on-and-off wing beats.

For those readers interesting in watching one of our most fascinating songbirds, you can easily locate one by visiting an open field. If you spent time observing their behavior, knowing where a favorite perch might be, you also are likely to find impaled prey.


At 2:03 AM, Anonymous Opal said...

It cannot succeed as a matter of fact, that's what I suppose.


Post a Comment

<< Home