A studio for bird study

Tag: buteo

Migration

by Bryce W. Robinson

"Migration" 18x24" acrylic on canvas.

“Migration” 18×24″ acrylic on canvas.

I’d like to thank Mr. Mike Shaw for the generosity he extended me the past fall migration season. He was kind enough to lend me his pair of Zeiss 8×42 binoculars for the entire season. As a young biologist, I cannot afford luxuries like these binoculars. My ability to effectively document the migration to the up most accuracy was directly aided with this pair. For his kindness, I painted a scene of a migrating adult Red-tailed Hawk as I might have seen it through the lens. Thanks again Mike. I hope you enjoy this scene as much as I enjoyed my season.

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An Insight into an Interaction- The Red-tailed Hawk and American Badger

by Bryce W. Robinson

TO VIEW THE SCENE IN ITS ENTIRETY, WATCH VIDEO IN FULL SCREEN

While out conducting Golden Eagle surveys in the west desert, I stumble upon many interesting and peculiar things. Car carcasses are among my favorite, but often I come upon the fauna of the land, and stand privy to their every day lives.

This past week I stopped to look at a distant Red-tailed Hawk sitting atop a greasewood, only a few feet from the ground. This behavior is a bit peculiar for this Buteo. I see many Rough-legged Hawks sitting on bushes in the deserts, but in my experience, Red-tailed Hawks tend to prefer the power poles and rock ledges. The bird sitting low caught my eye, so I investigated.

I am so happy I took the time to look. What I observed is illustrated in the above video. Again, I apologize for the quality. It is the best I could put together with my mediocre digiscoping skills. Still, I was able to capture the scene.

An American Badger- Taxidea taxus, was milling about to the left of the perched bird.  To see a badger is a treat itself, but this experience was even more special. It seemed the hawk was paying a great deal of attention to the badger. Along with the hawk and badger, a raven sat on a pole just to the right of the hawk, scolding the scene. As you can see in the video, the badger seems to be digging, and moving something about. I can only postulate what the three creatures were up to.

I think that the hawk had some success in procuring a meal for itself, only to find its prey victim to some interspecific klepto-parasitism. That is, to say, the hawk was robbed of its kill by the badger. That would have been incredible to catch, but one is only so lucky. I believe the interaction in the video is simply a Red-tailed Hawk watching a badger burry its stolen prey. The presence of the raven adds some confidence to my diagnostic.

Experiences such as this are why field work is such an adventure. I hope this upcoming week brings more adventure, as I travel the desert in search of winged wonders.

by Bryce W. Robinson

Dark Morph Juvenile Red-tailed Hawk- Buteo jamaicensis

The past few months have been full of incredible encounters with the winged world. Recently I found a young Red-tailed Hawk perched atop a fence post along the roadside. I stopped to photograph the bird, as is my custom. I took notice of the dark coloration of the bird, which always excites me. As is possible in winter, I always get excited about dark Red-tailed Hawks and the possibility that they might be Harlan’s. I recently posted about how to distinguish between dark juvenile Westerns and Harlan’s. As I described, it is easy to see that this is a dark Western, not a Harlan’s. Still, I love the chance to see all of the diversity in the species.

What struck me about this particular bird was not anything dealing with plumage. I noticed a large clump of grass in the birds talons. Chuckling, I passed it off as a missed attempt at some prey, coming away with only a healthy talon full of weeds. I didn’t even raise my binoculars to check. Luckily, the photo tells the story. This young bird was successful in obtaining a morning meal.

It tickles me to find myself with a photo of a bird clutching its prey. The story continues, however. The bird lit off of the pole, headed away from the highway to a more secretive feeding spot. I was taken aback as a large tumbleweed flew with the hawk. I couldn’t help but laugh. In the desperate attempt to glean a morning meal, the youthful raptor grabbed more than its target, and couldn’t risk releasing the extras until it began consuming the meal.

I’ve seen some peculiar and comical behavior from young birds in the past. At the beginning of the migration season, I observed a juvenile Red-tailed Hawk grab a pine cone from a tree. It soared about for some time, regularly checking the object in its talons. One can only speculate as to what this bird was doing, but it was quite the sight, to be sure. These special instances display the character that birds possess, only becoming apparent with detailed observation, too often overlooked.

 

Differentiating Immature Dark Western Red-tailed Hawks from Immature Dark Harlan’s- A First-hand Experience

by Bryce W. Robinson

My time at the Goshutes Raptor Migration sight has come to a close. Never have I been witness to the magnitude and diversity that I observed in the three months that I lived on the nine thousand foot island in the sky. I came away with a large collection of spectacular photos far surpassing, in quality and content, anything I have ever gathered. Even more, I came away with a great understanding and appreciation for the phenomenon of the fall raptor migration. Field work is immersive in nature. The opportunity to learn and magnify my study in this situation is truly unmatched.

I find my interest intensely involved in the genus Buteo.  Specifically, I am enamored by the polymorphism present in this group. Of these birds, none matches the diversity and allure of the Red-tailed Hawk. The Harlan’s Hawk is quite possibly my favorite bird at the moment. I was obsessive about analyzing every Red-tailed Hawk that passed. Finally, near the end of October, I began seeing the birds of the great north. The banding station was hard at work, capturing and banding all that they could. Every morning I gave them my good luck speech about the inevitability of catching a Harlan’s on that day. Finally, they came through, trapping a dark juvenile Harlan’s Red-tailed Hawk.

Luck seemed to be on my side that day. I spent the majority of the season bothering the banders for pictures to document the diversity of the species. Earlier, hours before the Harlan’s was trapped, they caught a beautiful dark western bird. I was able to get photos of this bird. The result is my ability to show, with photos, the differences between the immature dark Harlan’s, and the immature dark Western Red-tailed Hawk.

I will first introduce and discuss the dark immature Buteo jamaicensis calurus:

Immature Dark Western Red-tailed Hawk- Buteo jamaicensis calurus

It is rare to find a solid chocolate immature Western. This bird is a nice, almost solid bird, however there is still a somewhat mottled appearance on the breast and wing linings. Dark western birds are a beautiful chocolate brown. On dark birds, the upper-tail coverts appear the same as the color of the scapulars and mantle. They do not have the contrast of the whitish upper-tail coverts that a light morph usually has. Sadly, this photo does not adequately display this feature. Of course most immatures have a heavily banded tail that is not the indicative brick red of adults, and they possess the obvious pale primaries giving the appearance of what is referred to as wing windows. The tail often reflects the color morph of the bird, as seen in this bird, having a color that matches the dark solid brown of the body. It is hard not to get too in-depth discussing color morphs of the Red-tailed Hawk. As this is not a discussion on the particulars of each morph, I will discuss the important features to contrast with those of the Harlan’s.

It is important to note that the features I discuss are not always reflected in identifying these birds. As diverse as the Red-tailed Hawk is, it often lacks or reflects certain traits that may throw ones identification into a confusing headache. As in most bird identification, it is necessary to incorporate many factors into an I.D.

For the dark immature western, first note the solid color of the upper-wing coverts, scapulars, and mantle. Also, the head of this bird lacks any mottling, or white markings. Pay particular attention to the area around the eye. As seen in the front view photo, the remiges are banded. The banding is not in heavy contrast with the general color of the wing. This factor is also present on the tail. One factor in contrast with an immature Harlan’s Hawk are the dark emarginated outer primaries. In most Harlan’s, these primaries are banded. I recently learned from Jerry Liguori that this feature is usually only reflected in immature birds. Adult Harlan’s often have solid outer primaries, much like western birds.

Here is the dark immature Harlan’s Red-tailed Hawk- Buteo jamaicensis harlani:

Immature Dark Harlan’s Red-tailed Hawk- Buteo jamaicensis harlani

Separated by the text from discussing the western, it might seem difficult to truly compare the two. Below I have included some comparison photos that can be referenced following the discussion. For now, pay attention to the factors of each bird exclusively. Getting to know the face image of a bird, rather than the nit-picky particulars of individual characteristics will better aid one in identification.

First, Notice the banding on the emarginated primaries of this bird. It is obvious on the front view of the bird, not so much on the backside. Although still a dark brown, this bird is obviously highly melanistic. Harlan’s are often severely dark, even black. This bird is not as dark as some, but it is obviously darker than the chocolate color of the western. The physiological reasons for this are extremely interesting, but for another discussion.

The most obvious feature of this bird, in conjunction with the dark coloration, is the presence of mottling across the body of the bird. This creates a bird of high contrast, which is a feature that might possibly be the reason for my addiction to the aesthetic of this Alaskan wanderer. The mottling is present on the breast, belly, and wing lining of this bird, however, this feature is not exclusive to the Harlan’s. The area to focus on in relation to mottling is the backside of the bird. Notice the heavy mottling present on the upper-wing coverts, scapulars, and mantle. This feature adds to the other factors that make the bird a Harlan’s. Also, notice the presence of white on the face and crown.

I note in the video below that the tail is heavily banded, and the presence of the contrasting white and dark in the tail is unique. These factors do not necessarily add to the identification of a Harlan’s, but it is interesting to note. The tail of the Harlan’s is quite different from the Western. The bands are thicker, and contrast more with the coloration of the rest of the tail. Take the time to see the bird in the video. I briefly discuss all the factors that make the bird a Harlan’s, but the video is really valuable to present the bird in a comprehensive way.

The following photos illustrate a visual to aid in intellectualizing the differences between the dark immature Harlan’s and Western.

Dark Western(top) and Dark Harlan’s(bottom) bottom-side

Dark Western(top) and Dark Harlan’s(bottom) topside

The experience I had this season left me with some impressions and ideas in relation to the Red-tailed Hawk. Much discussion and disagreement is present in the raptor world in relation to the status of the Harlan’s. I have some insight into the issue, provided by exposure to the number of birds I observed this fall, coupled with conversation, and personal study of the bird.

The plumage diversity present in the species Buteo jamaicensis is vast. I observed that the birds of the desert of southern California appear to have plumage differences from those that I observe in the great basin. Also, across the course of the season I documented through photography, the differences in the birds that traveled past the migration sight. I can say, through personal experience and observation, that there is so much diversity in the species that it becomes difficult to differentiate morphs, and at times, even supposed subspecies. The debate in the bird world in regards to the Harlan’s is whether or not it deserves a status as a separate species. I feel that the debate is arbitrary given the knowledge we have about these northern birds.

I even question the status of subspecies in regards to the Harlan’s. The parameters that factor into substantiating subspecies status are particular, however it is my impression that there is not enough known about the breeding ecology of the Harlan’s Hawk to definitively term it a subspecies. Perhaps the Harlan’s is a color morph, an exemplification of variation in plumage, not as geographically tied as we believe.

It ultimately comes down to my lack of knowledge and really, the lack of the collective knowledge of the raptor community. What needs to be done is a comprehensive study, documenting the movements and breeding ecology of Harlan’s Hawks. Through a well crafted scientific study, we can once and for all discover the knowledge that will lift us past what is now only a discussion in speculation.