September 13, 2018
The Common Black Hawk in the photo accompanying this week’s column is one messy looking bird.  Most raptor flight photographers, including this one, are drawn to their subjects by sleek lines and crisp patterns.  Common Black Hawk may well be my favorite Arizona raptor because, in fact, the species is NOT common north of the border, and because the broad wings and short tail combined with the coal black plumage, grayish bloom, and single white tail band do give this unique Southwestern hawk a sleek, crisp appearance, especially overhead.

There is a reason, though, why I was delighted to capture this image of this ratty, disheveled bird.  There is nothing about the plumage that indicates to me that it is a juvenile coming into adulthood.  This is an adult bird in heavy molt, and aside from Bald Eagles which go through so many molts before reaching full maturity, I cannot recall having taken photos of any other raptors in molt.

There’s a reason for that, too, of course.  I am typically out looking for raptor shots at two times during the year—winter when we have an influx of hawks from the north, and late spring/early summer when our resident raptors are establishing territory and feeding young.  During these seasons on a bird’s calendar there would never be molt going on, but this shot was taken a couple weeks ago along a waterway where I was looking for odonates and was taken totally by surprise when the hawk flushed.

The most stressful and dangerous activity in any bird’s life is migration, and that would be true even for short range migrants such as Common Black Hawk.  That is why birds do not molt on migration, but either before or after that fraught adventure.  It is assumed that molting flight feathers makes birds, which are after all evolved to survive by flight, more vulnerable to predation and aerial accidents.  Thus, molting birds are typically secretive and solitary.

We know adult Common Black Hawks migrate south before the juveniles which are often seen through September and into October.  Apparently adults, at least this one, molt before they leave, though this species has not been much studied and I could find nothing in a perusal of the literature to corroborate this.  In retrospect I found only two previous records of my own for adult Black Hawks later than the end of July, and one of those was a November sighting near Tucson of a bird that obviously didn’t get the message to get out of Dodge before winter.

The Black Hawk in the photo is missing several primaries, the secondaries which usually give this species its distinctive, broad winged flight profile appear uniformly new and uncharacteristically short, and the tail rectrices seem to have begun growing in at disparate times.  Primaries provide thrust, secondaries give lift, rectrices aid braking and steering.  Inadvertently I flushed this individual several times, probably because in its present state of molt it was reluctant to fly very far or was having difficulty doing so.

Next time you see an Arizona raptor out of season, late summer but before migration, be sure to notice its age and the state of its flight feathers.  Chances are the observation may provide a rare glimpse “behind the curtain” into the life history and survival strategy of a fascinating and beloved avian family.