I once witnessed a running battle between a very large woodpecker and a very small hawk.
Usually, when you see one bird attacking another, it falls into one of three categories: Predation, harassment, or intra-species competition. In predation, rarely witnessed, the predator attacks its prey with overwhelming superiority of strength and "weaponry," and the event is over in seconds. Harassment, which I've seen hundreds of times, can last for many minutes, even more than an hour, but nobody really gets hurt. Smaller birds, usually a number of them, rush near a larger bird, maybe sometimes getting in a peck or two, until they drive the larger bird out of their territory. Songbirds harass crows and ravens, songbirds, crows, jays, and ravens harass hawks, owls, and eagles. It happens all the time. Intra-species competition rarely becomes physical, but when it does, you'll see two male birds scuffling over a female for just a second or two, and then it's over.
But this fight was different. The two birds involved were rather evenly matched, as in intra-species competition, but they were of different species, and the fight lasted for several minutes.
The woodpecker, a pileated woodpecker (Dryocopus pileatus), is the largest woodpecker in the world, at least until there is unequivocal proof that either the ivory billed woodpecker (Campephilus principalis) or the imperial woodpecker (C. imperialis) is not extinct.
The hawk, which was either a Cooper's hawk (Accipiter cooperii) or a sharp-shinned hawk (A. striatus), is among the smallest of hawks.
I'm not entirely sure which kind of hawk it was, mostly because its tail feathers were so bedraggled from the fight. These two birds are quite similar in plumage, and there is overlap in their sizes, as a large female sharp-shinned hawk can be larger than a small male Cooper's hawk. One way to tell them apart is the relative length and width of their wings in level flight, which I never saw in this battle. Another way is the relative length of central and marginal tail feathers, which, as I said, were so bedraggled I couldn't tell. Still, I'm leaning toward this being a Cooper's hawk. It was significantly smaller than the woodpecker, but not really tiny as a sharp-shinned hawk.
So, I was taking a Saturday afternoon walk in Mine Falls Park. As I reached the northern shore of the Mill Pond, among a stand of old pines, there was a flurry of rustling wings and odd squawking in the treetops. A large ball of feathers erupted from the forest and headed out over the pond. When they reached about a hundred feet from the forest and about thirty feet above the water, they stopped and fought while trying to hover.
The woodpecker stood vertically, reaching out with its powerful claws to tear at the hawk. The hawk was also vertical, fending off the woodpecker's claws with its own talons and trying to jab at the woodpecker's breast with his hooked beak.
As they fought, they fell about ten feet closer to the water. Then they broke off, the woodpecker retreating southward to the shore opposite me, while the hawk flew off to the west.
I couldn't tell who had won.
I also couldn't quite figure out why they were fighting in the first place.
Cooper's hawks feed on songbirds, and will attack a bird nearly as big as themselves, but to attack such a powerful bird as a woodpecker, and one twice the size of the hawk itself, is suicide! No, the hawk was not attacking the woodpecker as prey.
A pileated woodpecker might harass a hawk that it perceived as a threat, though I've never seen any woodpecker harassing any hawk other than this odd event. Woodpeckers are powerful birds, but their weight and their short, rounded wings rob them of aerial agility. And why would the woodpecker perceive this diminutive hawk as a threat, anyway?
My best guess is that this whole thing began with nest predation, but that's still not a complete answer. The hawk might try to take the woodpecker's chicks if the nest was unattended. It is equally likely that the woodpecker might try to take the eggs or chicks of another bird, and an unattended Cooper's hawk nest looks just the same as the nest of a crow or a jay.
Yes, I figure one of these birds was raiding the other's nest, and the other was defending its chicks or eggs. But I'm not at all sure who was the raider and who the defender.
Just about the time I arrived at this conclusion, the fight was on again!
I didn't see where they came from but they were out over the pond again, flying on their sides, belly to belly, exchanging jabs with their feet. They were approaching the northern shore of the pond obliquely, and disappeared over the trees to the east of me.
Less than a minute later, they were back, flying over my head and out into the pond just like the first time I had seen them. This time, they hovered even longer and nearly fell into the water. When they broke off, the woodpecker came toward me and disappeared into the pine forest north of the pond, toward where I knew a pair of pileated woodpeckers were nesting. The hawk flew into the hardwood forest on the southern shore of the pond.
And so ended the most peculiar bird-fight I had ever seen, or would see until the next week. But that's another story.