Back in 2008 I first noticed a bird call in Dunn Woods that I had not heard in the wild before. (On the All About Birds link I provided in the previous sentence, it was the “begging call of chicks” that I first heard.) I wandered about a bit, and then saw a hawk like bird fly from one tree to another, where the calling had come from. I realized that there was a juvenile calling to one of its parents, who then responded.
I could tell from the size, short wings, long tail, and habit that it was an accipiter, not a buteo. I was standing on an inner path with my eyes fixed on the tree tops when a fellow from Germany asked what I was looking at. As I was telling him I had spotted a hawk, it flew right over our heads. I said I suspected it was an accipiter, but could not tell if it was a sharp-shinned, Cooper’s or even a goshawk. He immediately eliminated the goshawk, they are significantly larger than the other two, and really do not like being near humans.
He then was able to tell from the tail shape that it was a Cooper’s Hawk (Accipiter cooperii), which is rounded at the edges, while the Sharp-shinned hawk’s tail is squared off at the edges. So we know we had Cooper’s hawks in Dunn Woods, so I started looking to see if I could find a nest, and sure enough I found one high in the trees. Of course there a dozens of squirrel nests in woods, and they too are high in the trees too. But it is pretty easy to tell the difference, especially with a pair of binoculars. Squirrel nests are primarily leaves (for insulation) with some sticks for structure, while a hawk nest almost all interwoven sticks, they are distinctively different. I think that as the hawks use their nest only in spring and early summer, they do not need the insulation that the squirrels need to keep warm through the long winter months.
So for the past 8 years I have seen them nest in various parts of Dunn Woods; it seems they change nest locations every few years. On May 25, 2011 a strong storm took out the large sugar maple they had nested in that year. Sadly the two babies in the nest did survive the fall and/or the cool night air. I feared they would not nest again the next year, but thankfully they came back and nested in Dunn Woods again.
They have been in the same nest close to Bryan Hall for the past two years, and I feared they would not come back due to the raptor recordings coming from Bryan Hall in the evenings (to scare away the crows who like the roost by the hundreds in the woods during the winter. The sounds are still there in April, even the though the crows are long gone.
So yesterday I was in the woods when I heard the Cooper’s call coming from the trees, and was soon able to spot a pair flying from tree to tree while talking to each other. Steve Hinnefeld happened by just then and saw them too, and we agreed that they were a couple looking for a new nesting spot, or perhaps just courting. So I will be out every day now at lunch to see if I can spot a new nest before the leaves come out fully. After that, it is really difficult to see their nest until fall. But if you do know where it is, then the thrill is to find an angle (there is usually only one) where you can watch them sitting on the eggs. Incubation is done mostly by the female, and it usually takes 34-36 days for the eggs to hatch. The male brings food to female, and then incubates for a few minutes while female is eating. After hatching, he will bring food to the nest, and she will feed it to the fledglings. After about a month, they get restless and can be seen peeking over the nest (if you are lucky), and soon after begin to fly.
This is an especially interesting time. The juveniles will fly from tree to tree, and make quite a racket calling to their parents to bring them food. Fortunately Dunn Woods is filled with the small mammals and birds that the hawks feed upon, perhaps that is why they come back year after year. Several years ago I was watching a juvenile about 25 feet in a tree, calling for food when I noticed one of the parents about 20 feet above with a morsel of mammal in her talons. All of a sudden she called, and the lunch was dropped in front of the fledgling, but he/she just ignored it and it hit the ground. But I know I had just seen a hunting lesson, hawk style!
I do not have the fancy camera equipment of a true birder, so my pictures are less than useful for identification (and the pleasure of a good photo), but they do remind me of what I have seen and experienced in the woods. So here is a link to Google image search that has hundreds of images of Cooper’s hawks.