Ornithologi

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Tag: calurus

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.

 

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From the Field Journal- Golden Eagles at the Goshutes

by Bryce W. Robinson

Two full weeks have passed at the Goshutes, and already I have accumulated many incredible stories. Life on the mountain is as close to heaven as I can get at the moment, I am sure. I’ve decided to chronicle my time here in a field journal. I will share my experiences from the journal by posting particularly interesting accounts. What follows is an entry I made last week, after observing one of the most spectacular wildlife events I have ever witnessed.

August 21st, 2012

Early August has been fairly bird-less as far as migration goes. Although birds haven’t been moving through, a great host of local raptors are keeping me entertained. I have many stories and experiences to tell of a whiny young Goshawk, pestering Sharp-shinned Hawks, bold and curious buteos, and countless others. For now, I’d like to tell of an experience I had today on my observation post. Jerry and Deneb were helping me with the count, as my co-counter Steve had yet to arrive on the mountain. Jerry and Deneb are old friends of seasons past here at the Goshutes. It was rather enjoyable to listen to their banter as they interacted as old friends often do. Jerry helped pass the time, taking it upon himself to teach me the tricks and tips he has accumulated from some thirty years of experience counting migrating raptors. Needless to say the lack of birds was made up for with teaching, chatter and humor. 

About mid-day, the three of us, steeped in some conversation of trivial matters of the world, were rocked as an intense sound of friction filled the air. Looking above towards the source of the sound, we saw two large air masters pass directly overhead. In fact, what we observed were two large adult Golden Eagles engaged in a dramatic and deliberate stoop, heading directly east with conviction. Excited and in awe, we watched the birds descent. By sight and sound, the large Aquila birds resembled two fighter jets in arial pursuit. Near the bottom of the canyon, the two birds abandoned their stoop, spreading wings, slicing the air with legs hanging, a posture of aggression. As we watched, we realized their intention. Picking up a third bird, we saw the eagles close on a soaring buteo, an adult Red-tailed Hawk.

The unsuspecting buteo realized the danger just in time. It began evasive maneuvers to avoid the slashing talons of the eagles. The menacing eagles made pass after pass at the fleeing buteo. I was astonished at the sight of their cooperative offensive. Such slow soaring raptors had turned on their agile abilities, and it became apparent that these birds are masters of the wind and sky. The dog fight continued, and the skilled buteo somehow remained untouched by the merciless eagles. Finally, finding a bubbling thermal, the Red-tailed Hawk lifted swiftly in the air. The heavy eagles slowly pursued, but were unable to match the rising speed of the fleeing buteo. I was in awe at the violence I had witnessed. Such raw experiences rip away the feeling of fluffy beauty nature often promotes. The natural world is wild, harsh, and unforgiving. This time the hawk had evaded the eagles, and peace returned to the air. 

As we stood recounting the natural marvel we had just witnessed, our reflection was rocked by the majestic image laid out before us. To the east, against the expansive backdrop of the salt flats of western Utah, another Red-tailed Hawk joined the soaring victim of the eagles. Separated by hundreds of feet, two buteos above, two eagles below, raptors alike soared in unison, circling in the calm afternoon air. Taken aback, I again and for the hundredth time that week, voiced my feelings for the place. Full of magic and natural wonder, even before the migration has truly begun, the Goshutes has captured my heart, and I am truly at peace in this place. There is no where I would rather be, as I sit on a mountain top, feeling as close to heaven as is possible.

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.

 

 

 

 

 

 

A New Stride in My Study of Raptors Through the Lens

by Bryce W. Robinson

Swainson’s Hawk- Buteo swainsoni

And finally it has happened. An update from the Beatnik Birder, and a new development making a lengthy stride in fulfilling his study. After too long, I have upgraded my camera equipment. My lapse in posting of late is attributed to many happenings in my life. I have been birding, or out working with owls, but I have not had the time, drive, or energy to share my experiences. I have felt the void this has caused, and I am confident that the lull has passed.

The new drive comes from my new camera, the Canon 7D. Coupled with the camera, I purchased a 300mm f/4.0 telephoto lens and a 1.4x teleconverter. I’ve taken the camera out a few times already, and am working to learn all that I can as quickly as possible. I figure the amount of time I invest will be directly related to my success. I must now go to work. The camera will not only create loads of fun and play, but will become and invaluable tool for the research I’d like to accomplish on the world of birds.

I knew as soon as the camera came that I had a subject I was extremely interested in capturing. A few weeks ago, Mitch Tall and I went west along I-80 to see what we might find. We came upon a large number of Swainson’s Hawks hunting the pastures to the north of the highway. I was very surprised at the number of birds present in such a small area. Among the light, dark, and juvenile Swainson’s was also a young Ferruginous Hawk. This bird was the first Ferruginous I had ever seen in the Salt Lake Valley. I was pleasantly surprised, to say the least.

Now armed with my new equipment, I thought it fruitful to return to the spot in hopes of finding the same number of birds as before. The night before I had found a group of eight Swainson’s on a thirty acre plot near my parents. A trend perhaps, and future investigation will add to my ideas about migrant grouping in hunting grounds for raptors. I was certain I would come away with some great shots if the birds were again hunting the fields along the interstate.

When Mitch and I made it to the area where the group had been, we were a bit disappointed to find only a few birds perched and in the air, scattered much farther than before. Two young Red-tailed Hawks circled above, but had risen on thermals a bit too high to get a spectacular photo. Still reviewing the shots I did come away with, I was tickled and impressed with my new gear.

Juvenile Light Morph Western Red-tailed Hawk- Buteo jamaicensis calurus

I was lucky enough to find a few members of my target species. Most of the birds were circling far from the road, far out of range of my camera. Finally we had luck, coming upon a perched Swainson’s Hawk only two hundred meters or so from the road. Far enough to feel comfortable with our intrusion, but close enough for some worthwhile photography.

Swainson’s Hawk- Buteo swainsoni

After watching the bird for some time, and taking many many photos, we were fortunate enough to watch as the bird lit off pole #36. I missed the chance at photographing the bird as it left the post, but I did catch him gliding feet above the ground.

Topside of gliding Swainson’s Hawk, showing some apparent body and flight feather molt.

After seeing the bird fly, and land on a post farther down the road, I could tell that this bird was molting. From the photo of the bird pulling up just before landing on the post, you can see that P1-5 are fresh new feathers, and many of the outer retrices are actively growing in. Also, from the mottled look of the scapulars and upper wing coverts, it is apparent that the bird is undergoing a body molt as well. I reviewed some photos of the bird as it flew, and I a under the impression that this bird is molting into its first adult plumage. I love this stuff. I haven’t sent any of these to Jerry Liguori for conformation or review, but I’ll be sure to. After which, I will correct any mistakes I made, or even elaborate on what can be told from this bird.

Swainson’s Hawk- Buteo swainsoni. Note the remige and retrix molt, as well as the body molt of the upper wing coverts. The darker wing feathers, P1-5 are newly grown feathers, as well as the central retrices.

My main fascination with Buteos is the diversity in their plumage. Using my camera for a recording tool, I’d like to add to the work of Jerry Liguori in documenting the vast varieties that present themselves in these winged predators. My images at the moment are not near the quality they could be. I want to correct that. I know they won’t reach the Ron Dudley quality, but I will do my best.

Here is to the future of my study. Finally my photography will progress. Let’s hope the birds cooperate.

Juvenile Swainson’s Hawk- Buteo Swainsoni