Ornithologi

A studio for bird study

Tag: birds of prey

Published in the Journal of Raptor Research: Dietary Plasticity in a Specialist Predator, the Gyrfalcon (Falco rusticolus): New Insights into Diet During Brood Rearing

by Bryce W. Robinson

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I’m privileged to once again see a painting of mine don the cover of the Raptor Research Foundation’s quarterly publication, the Journal of Raptor Research. This time, however, is more special since the painting of a Gyrfalcon carrying its prey, an Arctic ground squirrel, corresponds to the feature article authored by myself and Travis Booms, Marc Bechard, and David L. Anderson.

Our publication titled “Dietary Plasticity in a Specialist Predator, the Gyrfalcon (Falco rusticolus): New Insights into Diet During Brood Rearing” details patterns we documented through implementation of nest cameras in 20 Gyrfalcon nests in 2014 and 2015. The largest camera study of nesting Gyrfalcons provided us with many new insights into the biology of this species, some of which we have already published, some that we have not. In this publication, we document a previously undescribed shift in prey use throughout the nestling period, from a diet of mostly Ptarmigan early in the season, to squirrel in the late season. This shift to squirrel is an important consideration on many levels. It highlights the nuances to Gyrfalcon prey use in Alaska, and the potential importance of squirrels in the later season for juvenile success and development. The apparent importance of squirrels also has implications for understanding ecosystem changes and how shifts in prey landscapes may impact Gyrfalcon reproduction. The stage is set to explore further.

Below are a few photos that describe the work that went into producing this publication. These highlight a some of the >750,000 nest camera images we collected from which the diet was quantified, as well as photos of the field work, and the people that made this effort possible. 

You can read our paper in the Journal of Raptor Research here:

https://bioone.org/journals/journal-of-raptor-research/volume-53/issue-2/JRR-15-58/Dietary-Plasticity-in-a-Specialist-Predator-the-Gyrfalcon-Falco-rusticolus/10.3356/JRR-15-58.full

Gyrfalcon nest 1

A female Gyrfalcon feeds nestlings. Image copyright Bryce W. Robinson/The Peregrine Fund.

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A female Gyrfalcon feeds her newly hatched nestling, alongside hatching eggs. Image copyright Bryce W. Robinson/The Peregrine Fund.

Female Gyrfalcon feeds nestlings Arctic ground squirrel

Female Gyrfalcon delivers an Arctic ground squirrel to nestlings. Image copyright Bryce W. Robinson/The Peregrine Fund.

Gyrfalcon nest 2

A female Gyrfalcon stands alongside c. 14 day old nestlings. Image copyright Bryce W. Robinson/ The Peregrine Fund.

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Parental care photo 1. A female (left) broods newly hatched young, reluctant to leave the nest at the male’s (right) arrival. Every Gyrfalcon would occasionally look at the camera, as seen here, but were otherwise unaffected by its presence. Image copyright Bryce W. Robinson/The Peregrine Fund.

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Parental care photo 2. In some cases, males were keen to participate in brooding and feeding young, as is shown here. In even fewer cases, the females were tolerant of this behavior. Image copyright Bryce W. Robinson/The Peregrine Fund.

Bryce and Gyrfalcon nest camera

Bryce W. Robinson sights in a nest camera at a Gyrfalcon nest. Image by Caitlin M. Davis.

Bryce rappelling into Gyrfalcon nest

Bryce W. Robinson rappelling into a Gyrfalcon nest in western Alaska. Image by Neil Paprocki.

Special thanks to the following people that made the field work happen

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John Earthman and Tinsel

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Neil Paprocki

Ellen in Gyrfalcon nest with nestling

Ellen Whittle holding a Gyrfalcon nestling in 2015.

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Mark Jeter and Ellen Whittle against an Alaskan landscape in 2015.

Special thanks to the institutions that made this work possible: Boise State University, Alaska Department of Fish and Game, and The Peregrine Fund

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Illustrating the Harpy Eagle

by Bryce W. Robinson

Untitled-3-01.jpgOver the past few years I’ve had the opportunity to illustrate the Harpy Eagle (Harpia harpyja), with the cover art for the Raptor Research Foundation‘s Journal of Raptor Research, and private commission work. Recently, I’ve focused again on the Harpy for a large and exciting project I’ve started with The Peregrine Fund (Stay tuned for details), and I’ll soon be returning to the species for Costa Rica focused work that I’ve also undertaken. I hope you enjoy the products of these upcoming endeavors as much as I’ll enjoy creating them.

Prints highlighting some of these Harpy Eagle images can be found in the shop.

Fall Migration Poster Series: Light Morph Adult Buteos

by Bryce W. Robinson

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Image copyright Ornithologi – Bryce W. Robinson

Share, use, and enjoy this infographic. Fall migration is starting!

A poster of the above image is available in the shop. Here you can also get a limited edition print of the original artwork used to create this infographic as well.

An Illustration of Some Members of the Genus Buteo

by Bryce W. Robinson

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18×24″ Gouache on watercolor paper. From top left: Rough-legged Hawk (Buteo lagopus), Swainson’s Hawk (Buteo swainsoni), Broad-winged Hawk (Buteo platypterus), Red-tailed Hawk (Buteo jamaicensis), Red-shouldered Hawk (Buteo lineatus), and Ferruginous Hawk (Buteo regalis). Purchase limited edition prints here.

I’ve been illustrating raptors in flight for some years now, which really took off when I met Jerry Liguori. Jerry took me under his wing, so to speak, and filled my head with everything he himself has learned over his many years studying the identification of raptors, particularly in flight. His tutelage accelerated my skills and knowledge in raptor identification, and I can confidently say that without his selfless teaching, my illustrations wouldn’t be the same.

I’m currently focused on tuning in my raptors in flight. I am about to start some large illustration projects focused on these taxa, so I am working to develop my technique and process as well perfecting relative shape and sizes. It’s a challenge, because illustrating each correctly involves so much more than the obvious differences in plumage. What makes each unique are shape, proportion, and posture. I’ve found posture to be the most challenging aspect to capture, since this seemingly simple factor has so much power over whether the bird looks real or not. Furthermore, in flight postures and shapes are influenced by the direction and motion of a bird in that moment in time. For instance, a bird soaring has a unique shape but because of the position of the viewer, that shape may be different for each wing because of the birds posture and how wind or resistance bends the outer primaries. To understand and master this effect is going to take repeated sketching and exploration.

Purchase an 18×24″ limited edition archival print (30 available) of this illustration in the shop. Your support helps me continue to refine my illustration, so thank you ahead of time! Also, be sure to add Jerry Liguori’s unique guidebooks to your library. Jerry has taken raptor identification to the next level, and his guidebooks are a wealth of information for mastering in-flight identification. You can find his books here: Jerry Liguori’s Hawk’s From Every Angle and Hawks at a Distance