Harris’ Hawks — Hail, Hail, The Gang’s (Almost) All Here

You may enlarge any image in this blog by clicking on it.  Click again for a full screen image.

The image in today’s post will win no awards for nature photography, but I think that it isn’t a bad bit of photojournalism.

A few days ago I was driving down a rural road.  Off in the distance I saw a utility pole with a series of strange looking vertical projections on the cross beams.  It looked weird, this pole, and I wondered what sort of electrical equipment had been installed on it.  Furthermore, I was disconcerted because I’d passed the identical pole a few hours previously, coming from the other direction, and the projections hadn’t been there then.

The mystery cleared up as I drew closer to the pole.  Those projections weren’t pieces of electrical equipment, they were large birds — Harris’ Hawks to be exact.  There were four of them on that pole and two more on the next pole down the road.

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Harris’ Hawks are an icon of the Sonoran Desert.  People come from all over the world just to see these raptors, and with good reason.  They are the only birds of prey in North America that live and hunt communally.  Harris’ Hawks are a species that originated in Latin America.  They’ve extended their range northward and now can be found in southern Arizona and southwest Texas.  But nowhere else — not in Texas or in Latin America — do these birds live communally.  They do so only in Arizona, and their reasons for doing so remain a subject of interest for ornithologists.

Here, they live in family groups.  They often hunt as a group, surrounding and mobbing prey, like jackrabbits.  Each family is dominated by a matriarch — a female — who calls the shots.  She’s the boss.  Her immediate subordinate is an alpha male with whom she mates.  Offspring are integrated into the family except that females, as they mature, are sent off, hopefully to start families of their own.

I think that the matriarch in this family is the second bird from the right.  Harris’ Hawk females are much larger than males, up to 40 percent larger.  That’s a common feature with most raptors.  It’s something called “reverse sexual dimorphism” with females invariably being larger than males.  The second bird from the right is clearly much larger than the two birds to either side of her.  The bird on the left appears to be as large or nearly as large as the one that I believe is the matriarch but that may have a bit to do with the angle at which I was standing when I made the photo.  After observing these birds for a minute or so, they all flew, except that the “matriarch” remained behind, watched me balefully for a few seconds, and vocalized, before leaving.  I interpret that — perhaps incorrectly — as another sign of dominance.

There are probably a few dozen Harris’ Hawk families living in and around Tucson.  These hawks urbanize easily, adapting well to local situations.  I’ve seen groups of these birds roosting alongside urban streets and in shopping mall parking lots.

Image made with a Canon 5Diii, 100-400 f4-5.6 ISII zoom lens, aperture priority setting, ISO 640, f8 @ 1/2500.

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