Shrikes Are Back! Winter Isn’t Far Behind
by Ro Wauer
Several loggerhead shrikes are back on their wintering grounds. These little predators are once again back on fence and utility lines throughout South Texas. Although a few actually remain year-round, the winter population is much greater. The majority of our wintering birds migrate north in spring to nest elsewhere. But now, their harsh trill or rattle calls can be heard at almost any open field.
Shrikes 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.
The loggerhead shrike is most unusual in a number of ways. Unlike most other songbirds, it preys on birds, mammals, lizards, and small snakes, as well as a wide variety of insects. But because it does not possess sharp talons to tear its prey apart, as do the larger raptors (hawks, eagles, falcons, and owls), it must utilize a different technique. Therefore, it has learned to impale its prey on sharp yucca leaves, cactus, and other thorns, barbed wire, and such. It can then feed on the carcass for several days. It is not uncommon to find several prey species impaled on a fence or on a certain spiny shrub. The prey is almost always suspended with its head up and body hanging down. This impaling behavior has given the loggerhead shrike the name “butcher bird.”
Recent studies have shed new light on the shrike’s unusual behavior. On its nesting grounds where impaled prey are most evident, the numerous impaled prey specimens represent the male shrike’s hunting prowess in attracting a female shrike. Males with the larger number of impaled prey are first to attract a mate. Although both sexes impale prey year-round, decorated spiny structures are most common on their nesting grounds.
As many as 72 species of shrikes are known worldwide, but only 2 occur in North America, the northern shrike of the northern boreal forests and the loggerhead shrike of the central and southern states. All of the world’s shrikes are small to medium-sized birds, 7 to 10 inches long, with large, broad heads and stout bills that are strongly hooked and notched near the tip. The notched bill is very similar to that of falcons. 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 bill which can sever neck vertebrate of its prey.
Small birds can be swallowed whole, and their feathers and bones later regurgitated, but larger prey are carried to favorite sites and impaled where they can be eaten at their leisure. Shrikes are fascinating birds, and the number of loggerhead shrikes that over winter in our area offer us a great opportunity to watch a most unusual songbird.