Saturday, April 10, 2010

Northern Shrikes

Just when  I thought I'd safely categorized Shrike--versus Northern Mockingbird--I find that I am in the range of Northern Shrike instead of Loggerhead and they're not the same!  At home in Tucson, we're in the range of Loggerhead Shrike--only--but now that we have crossed the international border to the north, we are in the land of Northern Shrike and my learning has to expand, eh?
On a first glance the two Shrikes are pretty similar--and I may be forgiven for enthusiastically calling "Loggerhead" upon our arrival in BC.  The silence from my driving companion--a veteran birder of thirty-five years--assured me that I had made a mistake.  I looked again (in fact I turned around and stopped the car) and observed the bird more closely, that is I stared at the head.  The head appeared to be rounder than usual and the eye mask was rather limited--projecting only behind the eye and not extending across the forehead.  Also, this bird had a white forehead where the Loggerhead has a black one--a distinctive feature, IF you can see it.
So, it's not much to go on--both Shrikes perch in similar locations and both sound--at least to me--similar, but if you pull over and gaze next time you're in the presence of a Shrike, the chances are you'll get it down to species as long as you're in Arizona or British Columbia, and as long as you're not witnessing the first record of Brown Shrike in BC!

Saturday, April 3, 2010

Shrike, are you mocking me?

When I get a nice, up close look at a Loggerhead Shrike such as this one I simply enjoy the view--and am grateful that I am not a lizard, rodent, get the picture. But when I see said Shrike from a distance, I find it rather easy to be mislead into believing that I am seeing a Northern Mockingbird. Color and pattern are similar--grey with a white wing patch; perch location is similar--tops of trees; and topography is similar--open fields. (Shrikes do appear in urban settings, but far less frequently than Northern Mockingbirds, so I am usually pretty careful before claiming to have seen one in the city).

With experience--and magnification--they really aren't all that similar. Their Gestalt is in fact rather different. While the Northern Mockingbird (and yes, there are southern Mockingbirds--but none are called Southern Mockingbird) is long and slender, the Loggerhead Shrike is long and rather rectangular. In addition, Shrikes in general have large, fat heads while Northern Mockingbirds have rather flatter, smaller ones (all this in comparison to their respective body sizes). The bill shapes, too, continue this distinction as the Shrikes have rather fat, hooked bills while the Northern Mockingbirds have slimmer, thrush-like ones. Lastly, their calls differ: the Loggerhead Shrike has a buzzy one while the Northern Mockingbird sounds more like a 'chack' 'chack'. Most helpful, however, is their song: while the Shrike has a repetitive, buzzy note, the Northern Mockingbird indulges in a wide variety of songs--from mimicking car alarms, to alarm clocks, to mourning can pretty much count on the fact that if you hear a 'weird' song, you're listening to a Northern Mockingbird. Now a real challenge would be an urban Shrike being imitated by a nearby Northern Mockingbird....I'll post that if it ever happens!