Juvenile And Adult Cooper’s Hawks

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About ten days ago I featured a post about a Cooper’s Hawk that I’d seen in a rural area.  Today’s post is about Cooper’s Hawks in a more familiar setting — within the urban sprawl of Tucson.

Sweetwater Wetlands is an extremely popular hangout for these raptors.  I often will encounter three or four of them in an hour’s walk at that location, particularly in early morning or late afternoon.  The other morning I was walking the wetlands’ perimeter when I saw a Cooper’s Hawk sitting atop a post.  This bird was quite young, judging from its plumage, almost certainly a juvenile that had fledged this past summer.

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Very young Cooper’s Hawks, like this bird, are distinguished by their chestnut-colored plumage and by their pale yellow eyes.  In older birds the dark plumage on their backs, the tops of their heads, their outer wings, and tails, turns gray, and their eyes become a very distinctive burnt orange or ruby red.

This youngster ignored me.  I stood barely 20 feet from it and it acted as if I didn’t exist.  Instead, it stared intently at something to its left.  I took a few photographs of it and then shifted my gaze in order to discover what the young bird was staring at.

It was an adult Cooper’s Hawk perched about 15-20 feet away.  The older bird was in the process of finishing eating something, perhaps a small bird.  It was staring back at the youngster.

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The older bird was pretty big for a Cooper’s Hawk and had a very broad breast.  She was much larger than the young bird.  The size differential suggests that the adult bird is a female and the youngster is a male.  Female Cooper’s Hawks tend to be larger, often much larger, than males.  The relatively small size of the young bird is not a sign of youth because young Cooper’s Hawks attain near-adult size within 30 days or so of hatching.  Rather, the smaller size suggests male gender in this bird.

What is the relationship between these two birds?  Possibly, they are unrelated.  It may have been a coincidence that they were perching close to each other and the young hawk may have been interested in the adult’s meal simply because it was hungry.  Also possible, however, is that the adult bird is the youngster’s mother.  However, that doesn’t mean that a parent-child relationship continues between these two: adult Cooper’s Hawks stop feeding their offspring about 30 days or so after they fledge.  This young bird would most likely have fledged in July or August at the absolute latest and so, it is way past the time when Mom cared at all about the welfare of her child.    If the adult is the mother bird, the youngster’s longing gaze in her direction is just wishful thinking on its part.  For better or worse, the young hawk is on its own at this time and must struggle to find its own food.

And, a struggle it is.  The attrition rate among young raptors — including Cooper’s Hawks — is very high during their first year.  About 70 percent die, either from starvation, predation, or accident. Young hawks must learn how to capture prey through trial and error.  Those who fail to learn starve.

Images made with a Canon 5Diii, 100-400mm ISII zoom lens+1.4x telextender, aperture priority setting.  The first image shot at ISO 500, f8 @ 1/640.  The second, at ISO 1250, f8 @ 1/800.

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