A Bounty of Summer Buteos

by Bryce W. Robinson

“Intermediate” morph Swainson’s Hawk- Buteo swainsoni.

Yesterday I ventured out to find some raptors with Jerry. We found found an area covered with “summering” Buteos, in densities unprecedented in my young and limited experience with the raptor world. I am enthralled with the ecology of wintering birds of prey, primarily for the interspecies interactions that occur in high density hunting grounds. Yesterday, I found the same densities and something of the same diversity. I have never seen so many Swainson’s Hawks and Ferruginous Hawks in one area. I was very delighted to observe numerous interactions between each species. Surprisingly, the bully seemed to be the Swainson’s Hawks. The Ferruginous didn’t seem to mind the Swainson’s, but a few times I observed Red-tailed Hawks being bullied by the summer migrants.

One particular incident made my day, and provided me with a glimpse of something I’ve never seen, and actually was unaware existed. A Swainson’s hawk and Red-tailed Hawk soared together rather high in the noon sky. The Swainson’s began buzzing the Red-tailed Hawk, resulting in some dramatic arial displays as they twisted to push the other away. Finally the climax of the interaction came when the two birds latched talons and began tumbling through the air. After multiple rolls, the birds broke, sending the Red-tailed Hawk fleeing from the scene. I have seen tumbling between Red-tailed Hawks as they engage in talon clasping to reinforce pair bonds, but never as an aggressive territorial interaction between two different species. The birds were some distance away, so the photos I came away with are not ideal, but interesting nonetheless.

Red-tailed Hawk (top) and Swainson’s Hawk (bottom) engaged in an aggressive tumbling interaction.

Birds blanketed the valley. Every other telephone pole supported a perching buteo, and the irrigation lines were covered with ravens and buteos as well. On one particular raven-less wheel line I counted eleven birds, comprised evenly of Swainson’s and Ferruginous Hawks. Not only was there interspecies diversity, but within each species, variation in plumage was present as well. I love dark morph Ferruginous Hawks, and a few flew around. These birds were leery of our intrusion, so I was unable to get any good photographs. I did photograph a very interesting adult Ferruginous. I assume it to be something like a rufous morph, perhaps in the midst of body molt, however its present state gave it a tiger like appearance. This is by far the most spectacular Ferruginous I have found to date.

“Tiger” Ferruginous Hawk- Buteo regalis

“Tiger” Ferruginous Hawk- Buteo regalis

I’m a plumage enthusiast when it comes to buteos, so this day was all that I could hope for. The diversity in Swainson’s Hawks was a treat. These birds vary immensely. I found the typical light morph birds, rufous birds, dark birds, and even some that exhibit mottling, perhaps intergrades between the morphs or showing body molt. I remember one particular bird near the end of the day that was nearly black, but it had extensive mottling not unlike a dark Harlan’s. Regrettably, I failed in my attempts to photograph this bird.

Intermediate Swainson’s Hawk- Buteo swainsoni

Light morph Swainson’s Hawk- Buteo swainsoni

It was surprising to find an area so devoid, relatively, of Red-tailed Hawks. There were few hanging about, most likely due to the attention they received from the gangs of Swainson’s Hawks. Still, we found a few birds and were able to come away with some photos.

Light morph Western Red-tailed Hawk- Buteo jamaicensis calurus

Juvenile light morph Western Red-tailed Hawk- Buteo jamaicensis calurus

The above birds was found sitting in a tree with a nest, and another young bird. Given their behavior, Jerry thought this bird to be very young, which is surprising given that most birds fledge early in the year. A late nest is peculiar, but it is highly probable that these birds have only recently taken to the air.

I have a few qualms about the photos I have shared. Although they are the best I have taken thus far, I failed to capture the catch light in most images, and for whatever reason many of the wings are blurred. I resolve to figure out how these problems can be corrected, but I feel great about my successes thus far. My homelessness and beatnik birding lifestyle continues for little longer, but in the small amount of time much will be chronicled. Let the good times soar.