ML632751827

Observation details

After following Mark Haller to the nest where he had photographed a light-phase Short-tailed Hawk over the weekend, I observed the nest from the opposite side of the canyon. A dark-form hawk flew in to a tree about 75 meters NE of the nest tree on the same ridge line. The flight profile was similar to that of a Black Vulture, with flat wings, except that the tips of the wings curved upward. The hawk soon flew closer to the nest tree, landing in full view about 30m from the nest. Plumage was entirely brownish black except for the underside of the rectrices. These were pale except for fairly evenly-spaced narrow dark bands and a broader dark subterminal band. I was unable to see the underside of the wings clearly, though did note, as the bird shifted, that there was some amount of pale plumage there. Wingtips approached the tail tip. Legs and cere were bright yellow, and there was some pale gray or white both above and below the cere. The bird was mostly silent, though several times gave a drawn-out cry descending in pitch, especially toward the end of the time it was present. It did not go to the presumed nest. At 10:22, it flew away, to the west. (On closer inspection of my photos, it appears that the hawk broke off a twig from its first perch and carried it to the second. This twig is visible in the bird's bill in the flight photo. That suggests the actual nest -- or a replacement -- is being built at the second location.) Since Short-tailed Hawks are known for having two color morphs, and for pairs to be of different color forms, I presume this was the mate of the bird Mark photographed last weekend. Thanks to Mark Haller for alerting Balcones Canyonlands Preserve staff to this nest, and escorting me to it, so we can divert any preserve activities away and minimize disturbance to it.