Broad-winged Hawk (Buteo platypterus) alert! In that last few decades, the mystery of Broad-winged Hawk migration has been slowly unraveling on southern Vancouver Island. Every fall, the species is now recorded in small numbers (usually <10 individuals) primarily from hawk watch efforts at Rocky Point Bird Observatory and Beechey Head.
I had an unfortunately brief but exciting encounter with a juvenile Broad-winged Hawk at Mount Tolmie on Friday (September 21, 2012) afternoon. I had never seen a juvenile Broad-winged Hawk on southern Vancouver Island and I'm not sure if that's because I primarily hone in on the more obvious pattern of adults or if they're genuinely less frequent here. I always enjoy actually identifying something rather than complacently accepting it as the obvious choice by range. As a result, I decided to go through the identification of this bird as a juvenile Broad-winged Hawk and not a Red-shouldered Hawk (B. lineatus). Before a well-documented record of an adult Red-shouldered Hawk over Rocky Point in 2009, the species was considered hypothetical based on a handful of sightings with insufficient details. Obviously I had a vested interest in trying to make it a Red-shouldered, but seeing a juvenile Broad-winged would be quite exciting as well.
I managed a couple photos which I mildly adjusted due to compensate for the extremely backlit conditions. When I first saw the bird, it had its wings swept back and was moving rapidly past me. It was much smaller (approximately two-thirds the size) than the Red-tailed Hawk (B. jamaicensis) just ahead of it, so my immediate reaction was Broad-winged Hawk. I thought I was never going to be able to say for sure because I lost sight of it in seconds, but I jogged up to upper viewpoint of Mount Tolmie on the off chance that it would find a thermal to rise up on and start circling again. And that's what happened. With a better look at the bird, I still suspected it was a Broad-winged Hawk but felt like I was in slightly over my head because it was a juvenile. I noted the pointed wings which seemed reminiscent of my previous encounters with adults, and that proved to be a helpful feature. Here are a couple cropped shots of the bird in question. I know the lighting is still bad, but I didn't want to make it too unnatural and possibly distort the actual appearance.
Aside from the wing shape and pale wing crescents, I was having trouble finding obvious differences between Broad-wingeds and Red-shouldered Hawks. I then realized most of the references I was looking over referred to the lineatus subspecies from the east and I should have been comparing to the western subspecies elegans. The bird documented in 2009 belonged to the latter and it is expected more will show up with their slow-but-continual northward expansion. Western juveniles have stronger barring on their flight feathers and are heavily marked with rufous-brown on the underwing coverts not unlike an adult, as indicated by a helpful information sheet from Princeton Press found here. As a result, if my bird was a Red-shouldered Hawk it would show some rusty tones on the underside of the wings. The individual I saw definitely did not possess any rusty tones under the wings. There has been one record of an eastern Red-shouldered in California, however, so it was good that I noted the pointed wings and lack of crescent-shaped panels near the wing tips just to eliminate this unlikely scenario, as well.
This exercise has been very enlightening for me and I think I will be that much more ready if a Red-shouldered Hawk decides to cross my path. Hopefully you gained something from this breakdown analysis as well. If you want to see more photos to compare some juvenile hawks, check this juvenile hawks in flight entry on the Stokes Birding Blog. Now get out and enjoy the hawk migration while you can!