Date: 4/29/18 5:10 pm From: Charles Hundertmark <chundertmark8...> Subject: [cobirds] Swainson's Hawk - Red-tailed Hawk drama at Waneka Lake, Boulder Co
After watching the White-faced Ibis flock at Greenlee Preserve this evening, I was delighted to spot my first-of-the-year Swainson’s Hawk. I first saw a single bird perched in a cottonwood near the spot where a pair has nested in previous years. It was being mobbed by Blue Jays and eventually flew. It was joined shortly by a second Swainson's Hawk in what I judged to be a territorial/courtship flight.
After a few minutes of high flying, the pair came lower toward the cottonwoods around the lake and were joined by a third bird. The third bird flew ahead of them and perched high in a cottonwood. One of the Swainson's flew into a cottonwood some distance away, while the second flew low over the lake along the tree line in a leg hanging display that took him up to a perch perhaps 20 meters from the Red-tail and at the same level. The more distant Swainson's then flew in close to the this bird.
The two Swainson's perched close together for several minutes being watched by the Red-tail. Perhaps in response to jays that began mobbing it, the Red-tail uttered two calls. At the second call, one of the Swainson's flew directly at the Red-tail striking the bird in a talons extended attack. The birds tumbled together through the branches halfway to the ground until the Red-tail flew off.
I have known for some time that Swainson’s, because of their greater agility, are dominant over Red-tails, but this was the first time I’ve witnessed such a dramatic demonstration.