Ornithologi

A studio for bird study

Tag: juvenile

Differentiating Adult and Juvenile Gyrfalcon (Falco rusticolus)

by Bryce W. Robinson

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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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White Wagtail Breeding in Teller, Alaska

by Bryce W. Robinson

 

Working again in Nome this summer, although for a relatively short time, provided me with the opportunity to attempt to see some of the birds of the region that I had missed in previous years. One such bird was the White Wagtail (Motacilla alba). Before traveling to Nome, my friend Luke had informed me that he had already seen the species in a lagoon near the Red Knot camp, so my chances were promising.

Red Knot work was in full swing when I reached Nome, which limited the chance to try for the wagtails. In the meantime came a report of a White Wagtail AND a Common Ringed Plover (Charadrius hiaticula) in Teller some 40 miles from our camp. On 5 July, a day of rain and weather, we took advantage of the inability to work with Knots and headed to Teller to try for both birds.

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An alarm calling adult White Wagtail (Motacilla alba) in Teller, Alaska.

When we reached Teller we began the search, more focused on the plover than the wagtail as the bird was a lifer for most in the group and the wagtail was not. After 20 minutes of fruitless plover searching Luke spotted our other target, a wagtail at the north end of the village. Luke and I both set out to photograph and film the bird and soon realized it was carrying food. Another adult appeared, also with food, and our minds tipped to the possibility that these birds bred in the area. Jim (head of the Red Knot project) watched the food carrying adult and followed it back to an electricity box on the side of a nearby building. The bird entered the utility box, and exited without the food. We quickly backed the truck up below the box to gain access and check for nestlings. Sure enough a grass nest sat in the corner of the box containing small nestlings.

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Electricity box containing a White Wagtail (Motacilla alba) nest. Teller, Alaska.

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White Wagtail (Motacilla alba) nest. Teller, Alaska.

After quickly documenting the nesting situation we left and let the adults return to provisioning the young. At the end of the day we left Teller with an excellent experience with White Wagtail, but unfortunately no Common Ringed Plover. Such is birding.

A few weeks later on 22 July, Luke and I returned to Teller on another poor weather day to check on the success of the brood. We soon found multiple juvenile wagtails chasing the adults, begging for food. Luke mentioned that White Wagtail had bred in Teller in years past, but I was left feeling like I had just struck oil – My first White Wagtails, breeding at that!

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Juvenile White Wagtail (Motacilla alba). Teller, Alaska.

The experienced left me excited. I’ve found that the best way to deal with the hangover excitement of a great birding experience is to illustrate, so after the initial sighting of the adults in early July I took advantage of the next day of weather and painted a White Wagtail on the inset of my Nome 2016 sketch journal.

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White Wagtail (Motacilla alba) in the inset of a 2016 field season sketch book for birds of the Seward Peninsula, Alaska. 

Seeing a bird species for the first time, and one that is quite uncommon in North America at that, is the best of birding. Especially if it feels like its been a long time coming. To see the bird and gain a first hand account of its breeding habits, well that is something else. It has a context, and context is what makes my experiences fruitful. I love life histories of birds, especially regarding breeding. I consider this experience to be the example of the what I seek when I step out the door aimed at observing birdlife.

July 2016 in Nome, Alaska had some magic, or something. But it seems that it was a continuation of a theme that started in early May. I bet that if you were to ask anyone that traveled to Nome, AK in the summer of 2016 they would agree. It was special summer, and I can’t wait to hear reports of what the fall brings in the region.

Female Juvenile Northern Harrier- Circus cyaneus

by Bryce W. Robinson

Female Juvenile Northern Harrier- Circus cyaneus. 11x15" watercolor on paper.

In honor of the delicate beauty of everything female, I painted the Northern Harrier. Although common, I find myself enamored and entranced with every view of this bird. The young females seem especially vivacious, with the teetering wander to hunt for prey and the dainty image while perching to preen. My goal with the female juvenile harrier was to capture the youth and liveliness in  character, portraying femininity common to all creatures, yet remaining true to the birds identity and wild nature. Perhaps a lofty goal, but worthy of the effort nonetheless.

Adult harriers are sexually dimorphic, but differences can also be seen in juvenile birds as well. Typically, a juvenile Northern Harrier is a cinnamon brown with a beautiful reddish breast. The difference between the male and female is seen in eye color. It becomes a challenge to sex juveniles in the field, as you often see harriers on the wing, and hardly perched. When the chance arises that you find a tolerant youngster, take note of the eye color and any other differences that stand out. I remember a day while photographing harriers with Jerry Liguori, when we were taking shots of what we thought to be an adult female. After reviewing the photos and seeing a few key details, namely eye color, Jerry recognized that the bird was in fact a young male. These particulars can add more fun and excitement to the challenge of raptor ID.

This painting was created while listening the musician Lisa Hannigan. I suggest coupling the visual with a like artist. It is sure to enhance the experience. Enjoy.

White-crowned Sparrow- An Identification Difficulty

by Bryce W. Robinson

As a raptor enthusiast, I know the challenge juvenile and immature birds can present when grasping for identification. Sparrows are a vastly diverse group, with multiple similar looking species. This coupled with the variation of juvenile and immature plumage has presented quite the challenge in learning field identification for these birds. I am currently on location in south central Utah conducting winter raptor surveys, and have seen a fair number of sparrow species in this high desert landscape. I was able to catch this photograph that displays an immature bird that may stump the beginning birder.

This is an immature White-crowned Sparrow ( Zonotrichia leucophrys). For identification, note the buff cheek. Also, note the prominent wing bars and overall fresh appearance to the bird. I believe the White-crowned Sparrow has a complex alternate molt strategy, so this bird has gone through a pre-formative molt transitioning from juvenal plumage into this immature “first winter” formative plumage. In spring it will transition into breeding or alternate plumage when it undergoes a pre-alternate molt.

As I am currently conducting winter surveys for raptors, I have gathered quite a few wonderful pictures and stories I am excited to share. I am working on learning aging of Golden Eagles, and will soon share some photos of a few birds, and my ideas as to their age. I saw a Harlan’s Hawk today, and will return to the area tomorrow with hopes of photographing the striking creature. With luck, I will have something to share.

Till then, enjoy life.

B William