For the Birds Radio Program: Northern Shrike
Blustery late autumn days carry to the northland birds from the far north, including one of the most pugnacious and predatory of all songbirds on this planet, the Northern Shrike. The “butcherbird,” which summers in the far north, winters from southern Alaska and central Ontario down through the state and beyond. A few wimp out the season as far south as Texas, but most tough out genuine winter.
The shrike takes spiders and all kinds of insects. Grasshoppers and crickets make up about 24 percent of the diet from spring to fall, and voles are another favorite. But this fierce killer also manages birds larger than itself, such as robins, Blue Jays, and Mourning Doves. The striking black and white pattern seems odd in a bird that would presumably want to sneak up on these wary species.
The word shrike is derived from shriek, from the harsh, discordant contact and alarm calls it makes, but as if to make up for the bold plumage, the shrike is usually silent, especially while actively hunting. The shrike bears the scientific name Lanius excubitor, from Latin for “watchful butcher.” It takes this and its nickname from its practice of impaling prey on barbs or thorns. This obviously allows it to store food against future scarcity, but helps in a second way, too. One of its prey species, the North American lubber grasshopper, produces an acrid toxin. If a young shrike eats one when it kills it, it quickly disgorges it. But if the grasshopper is stored for a few days first, the poison degrades, losing its potency.
Shrikes defend their territory and food stores throughout the year. Even on migration they go ballistic if they spot another shrike. One researcher found that shrikes will attack another shrike as far as half a mile away, with vision keen as a falcon’s. They lack true talons, so their faces are in jeopardy when hunting. Fortunately, their falcon-like beak has a tooth-like tip to the upper mandible and a notch in the lower. One quick bite in the neck with this lethal beak kills most prey instantly, giving the victim a painless death and the shrike insurance against retaliation.
Little birds disappear when a shrike flies to a treetop perch. If the shrike stops to eat a kill, suddenly littler birds reappear to scold it. Hearing chickadees piping tiny avian obscenities at a shrike is always amusing, but the chickadees are no birdbrains—when just a bit of the prey item remains, they disappear, knowing full well that a shrike will resume hunting even on a full stomach. Shrikes lead difficult lives, and if they catch two or even three animals in a single day, it will barely make up for one- and two-day stretches when they manage to catch nothing at all.
Most people are pleased the first time a shrike appears in their yard, at least until they realize it didn’t come for bird seed but for a more literal bird food. Some feeder watchers are philosophical about this, and some manage to keep shrikes visiting while keeping littler birds safe by offering the shrike other entrees. A few adapt to suet, but mice and shrews are far more enticing. I’ve known several people who made the best of a rodent problem by emptying their mousetraps onto a platform feeder for shrikes. One shrike even came to recognize the man who put a dead shrew in his feeder every morning. By the time the shrew supply finally ran out, the man had grown so fond of “his” bird that he started buying mice for it. He was lucky he only had one shrike that winter. One good tern may deserve another, but it’s one, two, three shrikes you’re out.