Shrikes? Yikes!

Loggerhead Shrike_JacksonLakeSP-CO_LAH_2024How would you like to be stalked, captured, then shaken so hard that your neck breaks—and then impaled onto a spike and left to age like a side of beef before finally being torn apart and eaten? That sounds like material suitable for a Halloween thriller. Yet, that’s your likely fate if you’re a mouse or lizard unlucky enough to catch the eye of a shrike. Shrikes are ferocious predators. It’s a good thing for us that they’re only about as big as an American Robin.

Northern Shrike_RMANWR-CO_LAH_8429There are 31 species of shrike worldwide. Two live in North America—the Loggerhead Shrike, Lanius ludovicianus, (above), which is present in Colorado year round, and the Northern Shrike, L. borealis, (left), which breeds in the far north and only shows up in the U.S. during the winter. The Northern Shrike’s range is circumpolar; it’s also found in Siberia. Until split off as a separate species in 2017, Northern Shrikes were considered a subspecies of the Great Grey Shrike (L. excubitor).

(Telling these shrikes apart can be a challenge. Check out my post from 2016 to learn how I go about it. )

While they may occupy different ranges, Northern and Loggerhead Shrikes are quite similar in other ways. Both carry the common name Butcherbird, in honor of their gruesome habit of impaling their dead prey on thorns, barbed wire, or other handy hooks. In fact, their genus, Lanius, is Latin for butcher. “Shrike” apparently derives the Old English scrīc, referring to their shrieking call.

There’s a reason for their grisly behavior. Like many raptors, shrikes will happily munch on anything they can catch—small lizards and snakes, turtles, frogs and toads, rodents, insects, roadkill, or even other songbirds. Most raptors have strong, clawed talons they use in capturing and eating their prey; shrikes, being perching birds, only have dainty little feet. So while a shrike is capable of catching and killing an animal as big as itself, the bird’s toes lack the strength to dismember it. By fastening the dead body to a stationary spike, the shrike can use its sharp beak to pull off bite-sized pieces, in much the same way that we stab a roast with a fork to stabilize it before carving off slices.

Brachystola magna_Plains Lubber Grasshopper_HomesteadRanchPark-CO_LAH_6974Impaling their prey serves another purpose as well. Loggerhead Shrikes, which spend their summers across much of the U.S., south-central Canada, and Mexico, eat large numbers of insects such as grasshoppers. But not all grasshoppers are safe to eat. Lubbers, such as the Plains Lubber shown here, are able to retain toxins present in the plants they consume; their bright colors warn predators to stay away or be poisoned.

Happily for the shrikes, however, the toxic chemicals degrade after a few days of storage. By saving the dead grasshoppers for later consumption, the shrikes are able to dine with no ill effects. (It’s unclear whether they eat the entire grasshopper, or first discard  the thorax where most toxins are concentrated.) Shrikes are also able to eat other poisonous prey, such as Monarch Butterflies and Eastern Narrow-mouthed Toads, by treating them in the same way.

Loggerhead Shrike_ElPasoCounty-CO_LAH_9418-001With their disquieting dietary habits, shrikes get a bad rap, but they have their sensitive side, too. When it comes to love, the males woo their mates. While he’s unlikely to show up with flowers, he will dance for the female, put on an aerial performance, feed her, and sing to her, hoping to gain her approval. Once they’ve agreed on a nesting site, he helps gather grasses and twigs, although she does the actual construction. Then he defends their home against intruders. In return, she’s faithful (for the most part), although once the young fledge, some females will then raise a second brood with a different partner.

How are our shrike species doing? Because they nest in the arctic, Northern Shrike populations are largely unstudied. Loggerhead Shrikes are more accessible, and we have better information on their status. Sadly, while they are currently fairly common, Loggerhead Shrike numbers are plummeting. Cornell’s All About Birds website explains,

Between 1966 and 2015, the species declined by almost 3% per year, resulting in a cumulative decline of 76%, according to the North American Breeding Bird Survey. … Loggerhead Shrikes have been listed as endangered, threatened, or of special concern in several states and Canada, and have been proposed for federal listing (the subspecies that nests on San Clemente Island, California, is listed as endangered).

While many possibilities have been suggested, no one really knows why the birds are at risk. More research is required to pinpoint the cause of the decline in time for the species to recover.

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