Ornithologi

A studio for bird study

Tag: gyrfalcon

Differentiating Adult and Juvenile Gyrfalcon (Falco rusticolus)

by Bryce W. Robinson

Gyrfalcon_Plate-01

Given that much of my career has been focused on the world’s largest falcon, the Gyrfalcon, I often get questions about their life history and Identification. A recurring question is the age of individuals that are observed in winter. Most often, folks ask about juvenile vs. adult, so I decided to make available a simple illustration with annotations as a reference for those with these questions.

What I’ve realized is that fleshy parts confuse a lot of people, since an adult should have yellow legs and cere, whereas a juvenile should have blue. However, it takes female birds much longer to change (well into their second year), and the coloration is also influenced by individual quality and hormones. Some adults, particularly females, tend to be quite dull in the winter (compare this with observations of gull legs in winter, e.g. California Gull). Adults that are likely three years or older (given presence of retained feathers in the upper wing, etc.) can have surprisingly dull legs that may appear blue under certain conditions. The key then is to take a step back and focus on the plumage, since in most cases it is quite straight forward.

The illustration above aims to highlight the key points for aging a Gyrfalcon between adult and juvenile. Eventually I’d like to visually describe more micro-aging factors, but for now I think this will be a helpful resource for those more unfamiliar with this species.

Please, feel free to send me feedback and suggestions. Constructive criticism is always welcome.

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Gyrfalcon (Falco rusticolus) Plate

by Bryce W. Robinson

Gyrfalcon_Plate_2017-11-03-online-01

My friend Kenneth, a Gyrfalcon researcher in Norway, is perhaps the most enthusiastically obsessed Gyrfalcon lover I know. I really appreciate his passion for the bird. Next week he is traveling to Salt Lake City for the Raptor Research Foundation’s annual conference. He asked me to paint a Gyrfalcon portrait for him, so I decided to take the opportunity to illustrate some perched birds to populate the plate I’ve been putting together. I going to produce some giclee prints of this plate, but I’m limiting it to 20 prints. If you like this image, and would like to purchase a print, it is available in the shop!

It’s taken me some time to paint birds that I’m pleased with enough to put into plate form. I’m still a bit at odds with these birds, but I think the above image best fits what I’m going for in creating the plate. My next step will be to paint some different postures and explore which best fills the gap in understanding the different positions and appearances that a Gyrfalcon may take on, in varying conditions. Additionally, the plate needs multiple different in flight postures, and some other age and plumage morph descriptions. Progress has been made either way, and I’m excited!

Below is the painting that I did for Kenneth, as it will look to him. I’ll be traveling to Salt Lake City myself, with this painting alongside me. Thanks for the opportunity Kenneth!

GYRF_Perched-online.jpg

 

Gyrfalcons in Flight Print: A Gift for the Falcon Enthusiast

by Bryce W. Robinson

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Gyrfalcons in Flight. From left to right, juvenile gray morph, adult gray morph, and adult white morph. 10×20″ Giclee print comprising three Gouache paintings by Bryce W. Robinson. Purchase this print in the store. $40 + shipping and handling.

If you’re looking for a gift for a falcon or raptor lover, or even for the general bird lover, consider this print available in the ornithologi shop. This print details three Gyrfalcons that I painted while working in Alaska in the summer and fall of 2016.

A Crested Auklet as a Prey Item in an Inland Gyrfalcon Nest as Detailed in Marine Ornithology

by Bryce W. Robinson

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Photo 1. Image of a Crested Auklet that was delivered to a Gyrfalcon nest, located over 100 km from the nearest coastline. Image published in Marine Ornithology 44(2) 229-231.

The fist publication from my Gyrfalcon research is now available online:

http://www.marineornithology.org/PDF/44_2/44_2_229-231.pdf

The account (Robinson and Anderson 2016) published in Marine Ornithology details a strange prey item, an adult Crested Auklet, delivered to one of the Gyrfalcon nests I had placed a camera in during the summer of 2015. All details are in the paper, so be sure to give it a read.

More Gyrfalcon publications to come!

Referenced literature:

ROBINSON, B.W. & ANDERSON, D.L. 2016. Crested Auklet Aethia cristatella as a prey item in an inland Gyrfalcon Falco rusticolus nest. Marine Ornithology 44: 229–231.