Thursday, October 9, 2008

Shrike: a Butcher Bird

Shrikes are predatory songbirds. In North America, the only resident member of the shrike family is the Loggerhead Shrike. It is similar to the slightly larger Northern Shrike, a European/Asian bird (known there as the Great Grey Shrike) which breeds in Canada and Alaska. The Loggerhead breeds in southern Canada and south to Mexico and prefers somewhat open areas and fields with scattered trees and shrubs…especially those with thorns. In the southern range, it is a permanent resident, but northern birds migrate south. The bird has declined in the northeastern parts of its range, due to loss of habitat (it especially enjoyed the hedgerows popular on farms gone-by) and pesticide use. It is critically endangered in Canada, where an experiment of captive breeding and release has been undertaken.

The bird is a smallish (8-9”, a bit smaller than an American Robin) gray, black and white bird that prefers ‘edges’ of habitat; along roads, hedgerows and open fields; especially those dotted with the occasional tree or shrub. It is a predator and looks like one; with a hooked bill used to kill insects, lizards, mice and small birds. It has a strong notch or ‘tooth’ near the tip that helps kill and hold a meal. However, because its feet are small and talons not so strong, this clever bird impales its prey on thorns and barbs to hold the meal while it feeds. Sometimes it may wedge a meal into the fork of a branch so it might rip its prey apart.

It is called ‘Loggerhead’ due to the large size of its head; gray with a black mask which looks some what like a blindfold, beginning narrowly above the bill and extending across the eyes toward the back of its head. Under parts are white; wings are black with white wing-patches. The back is gray and the tail black, with white outer-feathers. Its hooked bill appears heavy and is dark in color. Again, the Northern Shrike is similar, but its mask does not extend across the top if the bill and it is a paler gray, overall; its breast is slightly barred. Unlike the dark bill of the Loggerhead, the Northern shrike’s lower mandible is light-colored and appears heavier. Male and female Shrikes are similar in size and color; younger birds are more drab.

When hunting, the Shrike waits from a perch, watching below until it quickly drops onto prey or pursues it until it is tired; when it quickly hits and stuns the prey, carries it in its bill to a ‘hanging spot’ and impales it on a sharp thorn or barb. Once the prey is dead, the bird tears and consumes small pieces. It is this habit of impaling food that has earned its moniker:
“Butcher Bird”. I understand these opportunistic birds sometimes build a ‘cache’ of food, like other birds of prey…storing available food for later use. The rather gruesome collection of hanging carcasses also contributes to its nickname. I personally watched a Loggerhead Shrike scuffle with a bird of a different species, running it off, and then pull a dead grasshopper off a twig and offer it to a mate. Perhaps, like so many other birds, this is part of the mating ritual.

Another interesting habit: a Shrike hangs poisonous prey, including monarch butterflies and eastern narrow-mouthed toads, for several days which allow poisons to break down.

Research:

Photos on this post from Wikipedia

4 comments:

YC said...

I find the way these birds cache food fascinating. Do you have more images of the birds hanging meat? And highlight them? Neat!

Beverly said...

Nope, I posted all I could find, I think. I didn't take them...as I mentioned, I got the photos from Wikipedia...you could check for more.

I'm like you...I think they're awesome little things. I read they not only impale creatures for storage, they also wedge critters in crooks of branches (or impale them), so they are easier to rip apart. What smart birds, huh?

Thanks for visiting and leaving a comment; I appreciate it.

ehunter said...

I enjoyed that post. I knew about the impaling thing, but I didn't know about hanging food for days to allow poisons to break down, having a cache of hanging "game".

Interesting.

I will say that the first time I learned they impaled their prey I angsted over whether the prey was still alive or not while that happened. Probably sometimes it is.

Still, Loggerheads are neat birds.

Beverly said...

Aren’t they fascinating, ehunter? I just love ‘em!

I would imagine most of the time, the prey is dead. The Shrike’s bill is perfect for severing the spinal cord of most animals it catches. I recently watched a little video clip (doncha love YouTube?) where a Shrike attacked a mouse. I’m pretty sure it dispatched the critter before it hung it. For larger critters like that, I noticed it often just wedges the thing in a small branch. A still-wiggling creature would get away!

Thanks for visiting!!!