A studio for bird study

Tag: photography

September 8, 2014

Falcon Row

by Bryce W. Robinson

Image copyright Caitlin M. Davis

Image copyright Caitlin M. Davis

Caitlin Davis is in eastern Nevada again this fall, trapping migrating raptors at the Goshutes Raptor Migration Site for HawkWatch International. She’s been sending me more of her incredible raptor portraits. I felt compelled to share a composite she put together of this years birds.

The migration is in full swing and they have been catching great birds. Already the Goshutes crew has caught multiple individuals of four of North America’s falcon species: the American Kestrel, the Prairie Falcon, the Peregrine Falcon, and a few early Merlin. Perhaps this year they will get a fifth, the large emblematic falcon of the far north, the Gyrfalcon. I’d love to see that bird in Caitlin Davis portrait style.

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August 8, 2014

Late Summer is for Studying Juveniles

by Bryce W. Robinson

Juvenile Western Sandpiper - Calidris mauri

Juvenile Western Sandpiper – Calidris mauri

Late summer in western Alaska is relatively slow birding compared to the early summer arrival of migrants and vagrants. Still, it holds potential for finding wayward migrants that head the wrong way, or get blown in from a storm. Additionally, even though most adult shorebirds are long gone, hoards of juveniles have taken their place. In some cases, this is the only place to see these juvenal plumages, as many of these birds will make a pre-formative molt prior to reaching their migratory stopover sites or wintering grounds. Juvenile shorebirds can be a challenge, so I’ve taken the opportunity to sift through what I find and make sure I recognize everything.

The bird above and the bird below are both juvenile Western Sandpipers – Calidris mauri, yet they appear quite different in bill length and patterning. I have seen this difference in multiple birds, and at times I’ve wondered if I am simply misidentifying the second bird. I am confident that this is just variation in the species. So, I’m putting these birds up and welcome any comments on their differences. I could be mistaken, it happens often.

Juvenile Western Sandpiper - Calidris mauri

Juvenile Western Sandpiper – Calidris mauri

At the moment it seems that the only shorebirds I see are juvenile Western Sandpipers. The density here on the Seward Peninsula is shocking. On occasion there will be a number of Semipalmated Plovers intermixed in the flocks, and even more uncommon are Baird’s. It seems Least Sandpipers haven’t made it to the coast yet, or are already gone. Time will tell. Rock Sandpipers and Dunlin have started moving through, but I haven’t seen a single Red Knot on the coast. The other day I did find two vagrant juvenile Greater Yellowlegs, a very good bird for western Alaska.

It has been fun searching for variation, all the while considering the timing of each species movements and their strategies for vacating the breeding grounds. Birding in western Alaska in late summer is enlightening, and provides a greater understanding of how these creatures manage themselves year round.

 

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July 28, 2014

Rock Sandpiper – Calidris ptilocnemis, From Curiosity Stems Study

by Bryce W. Robinson

ROSA

Here in western Alaska I’ve been able to spend a bit of time pausing from a focus on Gyrfalcons to watch the Rock Sandpiper – Calidris ptilocnemis on its breeding grounds. My fascination with its appearance, behavior, and vocalizations caused me to look into what is known about their populations and distribution, a factor of bird biology that I’m growing evermore interested in studying. My investigation led me to understand that there occur three separate subspecific populations in Alaska, the nominate ptilocnemis of the Pribilofs, the tschuktschorum of the western mainland, and couesi of the Aleutian archipelago. As I am currently conducting research on the Seward Peninsula, I have been experiencing Calidris ptilocnemis tschuktschorum. 

After some further reading, I learned that the nominate ptilocnemis has the most northern wintering region of any North American shorebird. Remarkably, these birds spend their winters in the Cook Inlet of coastal Alaska. How they manage to find enough food and weather the extreme temperatures and conditions is above my current comprehension, but I was able to find some literature on the subject. Apparently, their is no physiological characteristic or attribute that separates ptilocnemis from other Rock Sandpiper subspecies that would give it the edge to winter so much farther north. The other Rocks could physiologically manage a winter in the north as well, but for whatever reason ptilocnemis is the only ssp. to do so. This seems like a peculiarity, and that is precisely why I am so fascinated by their distribution.

There are other Calidris species that are polytypic, and have separate wintering grounds for each subspecific population. Learning about such cases is extremely enlightening and begs for some contemplation on the matter. Perhaps a polytypic species such as the Rock Sandpiper, or the Red Knot will have an edge on anthropogenic induced changes affecting key migratory sites and their ability to survive the great journey. Perhaps the ability to buffer such disruptions is already built into their distribution at the species level. They are certainly better off than a monotypic species that stops over or winters wholly in a small and localized area. If the lower Pacific Coast of North America becomes a dead zone, then perhaps the subspecies couesi and tschuktschorum will be hard hit, but the nominate ptilocnemis may fair well and maintain a presence for the Rock Sandpiper in North America. As we attempt to be aware of our ever increasing impact, it sure would be nice to know that some birds will be able to wear the disruption, even if it is to a minor degree, so we can then put more energy into those more sensitive.

 

Referenced information:

Gill, Robert E., Pavel S. Tomkovich and Brian J. Mccaffery. 2002. Rock Sandpiper (Calidrisptilocnemis), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online:http://bna.birds.cornell.edu/bna/species/686

Ruthrauff, D. R., A. Dekinga, R.E. Gill, and T. Piersma. 2013. Identical Metabolic Rate and Thermal Conductance in Rock Sandpiper (Calidris ptilocnemis) Subspecies with Contrasting Nonbreeding Life Histories. The Auk 130 (1) pp. 60-68

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July 6, 2014

Alaska Birds are Gathering for Growth

by Bryce W. Robinson

Wilson's Warbler - Cardellina pusilla

In early July, Alaska birds are gathering for growth. I’ve been very focused on Gyrfalcon diet lately, but it too reflects the general trend of the season here. My eyes have been turning to the thickets lately, as the passerine nests have hatched out in large part. In the past week I have rarely found a passerine without a mouthful of assorted small insects.  The feeding frenzy is in full swing as hungry nestlings require massive amounts of food to fuel their rapid growth.

I appreciate the fast change here in the extreme north west of North America. It’s a great dynamic because it forces you to focus on the moment, as everything is fleeting. Soon, the adults will be joined by an abundance of juvenile birds to watch and study. I sure look forward to that!

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