Wednesday, May 20, 2009

Another Swainson's

And what a beauty, too! This is an adult dark morph Swainson's Hawk, seen today on and off for 45 minutes from the hawk platform. For a buteo, this is about as dark as dark morph gets: other buteos that have dark morphs (such as roughleg and redtail) always have lighter flight feathers, but all Swainson's Hawks - light, intermediate and dark morphs - have dark flight feathers. The fact that the body feathers and the underwing coverts are dark too make this a dark morph Swainson's Hawk. Unusual for a Swainson's, and unfortunately not well visible in my photos, are the tawny, heavily barred undertail coverts of today's bird. Only a relatively small percentage of Swainson's Hawks are dark morphs, and of those only a few have such heavily barred, tawny undertail coverts. Oh, this is one sharp-dressed raptor; here's a view of the upperside.

As most birders know, the Swainson's Hawk is a western bird. Within its range, it is quite common. Dark morphs are found only in the western half of that western range, roughly west of a line that runs from central Saskatchewan southward through eastern Montana, eastern Wyoming, eastern Colorado, to extreme eastern New Mexico. California has the highest percentage of darker birds (Wheeler 2003).

At Whitefish Point, the species is practically annual. In fact, it was seen in all but two of the last 21 years of hawk counting at Whitefish. Today's individual was the second this spring, and two is the average number for this species at Whitefish Point.

Here is the Swainson's Hawk on the right with a juvenile Rough-legged Hawk a little further back. Observe the long 'hand' of the Swainson's Hawk - that, and the dark flight feathers, are good field marks for this species.

It was a pleasant - and pleasantly warm - hawk watching day, with many folks of all ages stopping by on the platform. They were treated to a nice variety of raptors for this time of year, with 12 Turkey Vultures, 4 Bald Eagles, 9 Northern Harriers, 66 Sharp-shinned Hawks, 1 Cooper's Hawk, 26 Broad-winged Hawks, 9 Red-tailed Hawks, 4 Rough-legged Hawks, 2 Golden Eagles, 4 American Kestrels, 1 Merlin and 1 Peregrine Falcon.

The buteo count today is likely an undercount, as a larger kettle of about 80-100 birds was briefly visible only through the spotting scope. These birds were literally dots in the scope, and I didn't even try to identify them in the haze and the heat shimmer. They were probably a mix of today's species, presumably consisting of broadwings, redtails, Turkey Vultures, harriers and some eagles.

Wheeler, B.K. (2003) Raptors of Western North America, Princeton University Press, Princeton NJ.

1 comment:

  1. must have been a great day for viewing!!
    once again, *thanx* for the identifying tips-always a pleasure to log in each morning and see they are still flying strong! Truly a thrill to be there last week to see a Peregrine!! [my first in the US!!]
    Kathi in Brimley