Saturday, March 24, 2012


The heavy snow brought a carnival of birds into our feeders.  Starting at 6:57 a.m., with a black-capped chickadee, there was a steady stream of goldfinches, redpolls, red- and white- breasted nuthatches, blue jays, and even a hairy woodpecker. It was fun to watch as the tiny birds flew in and out of caves in the snow-laden branches of the hemlock trees. Sometimes we could see a little flake of snow stuck to a chickadee’s head, or caught in the whiskers around its bill.

Then, in a flash of feathers, they were gone.

The reason for their quick retreat landed on top of the snow pile. Sporting a black bandit-mask on his gray head, this Northern Shrike looked the part of a feathered villain.

Surprisingly, this skilled predator is a songbird. Being songbirds, shrikes lack the sharp talons of raptors like hawks and owls. Being songbirds, shrikes have another weapon. Like the winged Sirens of Greek mythology, shrikes sing sweetly to attract other songbirds. Once prey is lured in, shrikes attack with a solid blow, then finish the job by biting the neck, shaking, or repeated knocks to the skull with their sharp beak. Shrikes often kill more prey than is immediately needed and impale the leftovers on long thorns or barbed wire.  Impaling prey on thorns may seem brutal, but it is just a practical way to compensate for having delicate feet that cannot grip food during dinner.

The stored prey also provides the shrike with food security, and will eventually get eaten when the hunting is poor.  A male shrike with abundant prey impaled throughout his territory has a better chance of attracting mates and fathering successful nests. Breeding takes place north of 50 degrees latitude around the globe.  In winter, shrikes migrate only as far as necessary to find food, which often means they come into Wisconsin!  The visitor at my bird feeder should be one his way back home soon, to begin courtship in this month or next.

In the meantime, I hope he is finding enough to eat!  While I love my chickadees, I am an equal-opportunity bird feeder. Anyway, more than half of a shrike’s diet is small rodents like mice and voles.  Unfortunately, those tasty little critters are safely hiding beneath a foot of snow in the subnivean layer. While foxes and owls have enough mass to break through the crust and dig for tunneling mice, shrikes do not have that ability.  Thus, songbirds are a larger part of their diet now, as well as in early spring when male songbirds are distracted by courtship, and in late summer when fledglings are an easy catch. Insects, frogs, toads, and salamanders round out a shrike’s diet.

The carnival of seed-eating songbirds took their sweet time returning to my feeders. They seemed a little more skittish and a little more vigilant as we all scanned the treetops for another glimpse of our thrilling winter visitor.

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