A studio for bird study

Tag: prismacolor

Tail Pumping Behavior in the Black Phoebe

by Bryce W. Robinson

Black Phoebe - Sayornis nigricans. 14 x 17" prismacolor on bristol board. Image copyright Bryce W. Robinson

Black Phoebe – Sayornis nigricans. 14 x 17″ prismacolor on bristol board. Image copyright Bryce W. Robinson

The Black Phoebe – Sayornis nigricans in it’s simple suit of black and white, catches the eye of anyone remotely keen on the goings on of the natural world. This phoebe demands attention, even in a guild of flashy desert denizens. In doing so it provides some quality behavior birding that never disappoints.  

One behavior I have noted while watching the bird forage is the methodic tail flick, not uncommon in the family Tyrannidae, but somehow unique in the Black Phoebe. I’ve wondered about the habit, but never sought to satisfy the wonder until now. The illustration above came about in preparation for the coming San Diego Bird Festival that I will be attending. In practice, I decided to couple the illustration with looking into any insights in the literature regarding the tail pumping habits of the Black Phoebe.

In little time I found a paper (Avellis 2011). The study addressed four hypotheses explaining the behavior, the Balance Hypothesis where the phoebe tail pumps to maintain balance atop unstable perches, the Foraging Enhancement Hypothesis where tail pumping increases foraging success, the Signal to Territorial Intruders Hypothesis where the tail pumping signals conspecifics of the birds fitness and establishment on a territory, and the Signal to Predators Hypothesis where the tail pumps exhibit the birds vigilance amidst predators.

The results of the study indicated the following:

Balance Hypothesis – Not supported

Foraging Enhancement Hypothesis – Not supported

Signal to Territorial Intruders Hypothesis – Not supported

Signal to Predators Hypothesis – Supported

The paper reports that the Black Phoebe increased tail pumping rates significantly when a predator was detected either visually or audibly. The suggested purpose of tail pumping then is to advertise the birds awareness to the predators presence. Tail pumping communicates the phoebe’s health, and that it in turn will be a more difficult prey to capture.

So, when asked why the Black Phoebe pumps its tail, I’ll answer that the behavior is to exhibit the birds vigilance, acting as a deterrent for predators looking for the path of least resistance for procuring food. Another day, another bit of knowledge gained.

Referenced Literature:

Avellis, G. F. 2011. Tail Pumping by the Black Phoebe. The Wilson Journal of Ornithology 123:766-771

The Christmas Bird 2014 – “Pink-sided” Dark-eyed Junco

by Bryce W. Robinson

junco_copy

This year I chose a more common and well known winter bird for my annual year-end illustration The Christmas Bird. I chose a Dark-eyed Junco – Junco hyemalis, more colloquially known as a snowbird. The bird is fitting to represent the season, but I thought I’d make a bit of a twist to satisfy the nerds among us. I illustrated the subspecies mearnsi, the Pink-sided Junco. Those in the Rocky Mountain west are familiar with this bird, as it frequents feeders in mixed flocks with other Junco subspecies. It’s always a treat to see the distinctive pale blue-grey hood with a dark mask. I make sure to pay attention to the subspecies composition of Junco flocks here in western Idaho. We have flocks consisting mainly of “Oregon” Juncos, but occasionally we have “Slate-colored”, “Cassiar”, and the “Pink-sided”.

It is a bit strange to think that we are all at that point in the year once again. I certainly had a great year full of many birding adventures (3.5 months in western Alaska), plenty of satisfying illustrations, and loads of study and learning. I hope that others had an equally satisfying year. Here’s to another year of study and learning. Happy Holidays, and Happy New Year.

Burrowing Owl Illustration

by Bryce W. Robinson

Burrowing Owl - Athen cunicularia. 11 x 17" prismacolor on bristol

Burrowing Owl – Athene cunicularia. 11 x 17″ prismacolor on bristol

When I first began illustrating birds seriously almost three years ago, I spent the majority of my time on owls. For whatever reason, I was fascinated in the way their faces translated onto both canvas and paper. I remember when I realized the power that the eyes have for communicating the spirit of life within a creature. The exercise of illustrating owls taught me the importance of light and detail in the eyes of birds, especially raptors.

In the past I was focused on illustrating the face and busts of birds of prey. I stayed away from illustrating the full body of birds due in part to my fascination with the face, but also because I felt that I couldn’t create a proper and natural bird. Now I’ve started a campaign with myself to overcome my weaknesses and illustrate birds as a whole, either perched or in flight. While the exercise is to properly portray a bird in whole, I’ve made it a priority to take the lessons I learned from illustrating a birds face and invoke the same sense of life and attitude in the full-bodied bird.

Creating images of living creatures has more to it than I’ve ever thought. I see incredible paintings of Gyrfalcons in flight pursuing prey, or a Great Blue Heron stalking something in shallow water, and I can’t help but marvel at the mastery the artist holds over both their medium and their subject. I hope to reach even a fraction of the ability of some artists, but at the same time I’ve realized that perhaps the process is more enlightening and more worthwhile than the product. In the end, I’ll understand birds to a greater degree simply because I have put energy and focus into their details, and attempted to communicate their life and spirit through my own creative ability.

Molting Gyrfalcon in Flight

by Bryce W. Robinson

GYRF_Flight

While in Alaska this past summer conducting research on nesting Gyrfalcons – Falco rusticolus, I made many notes and observations concerning the stage of molt for each adult bird that I encountered. I’d like to share a few things that I noticed. I’m still a young student of ornithology, so none of this is new information, just a few interesting things that I noted and count as important information to retain.

First, I was interested to note the difference in stages of molt between male and female Gyrfalcons during the incubation period. The bird I have illustrated above portrays the stage at which most females molt had reached in early to mid May. Males on the other hand had either not initiated molt yet, or had just started. Needless to say, the general trend was that females were farther ahead of males and in some cases were even more advanced than what I have drawn.

Another interesting thing I noted was that this difference in molt stage by sex changed. Once the female began provisioning for nestlings, the females molt slowed as the males caught up.

I set out to illustrate a Gyrfalcon in flight to show some of my observations on molting Gyrfalcons, however creating the digital image of the illustration did not transfer some of the aspects I had hoped it would. One thing I noted concerning the body molt was that the rump was the first to be replaced. All birds in early summer had nice contrasting rumps consisting of fresh feathers. The mantle and scapulars as well as the upper wing coverts had yet to be replaced.

The Gyrfalcons in May were growing in feathers at their initiation points. In Falcons, this is P4 or 5, S4 and 5, the inner tertials, and in the tail the central deck feathers T1. This beginning stage is important for understanding the difference between hawks and falcons, and is another reason I wanted to illustrate a molting falcon

I love studying molt, and in the largest of the falcons it interests me to a great degree. Molt is costly, energetically. When you consider a large species that lives in a harsh climate such as the Arctic, it is remarkable that they complete an entire molt a year, save perhaps a few underwing coverts. Other large avian predators of the region like the Rough-legged Hawk and Golden Eagle do not do this, a fact that makes my respect for the Gyrfalcon grow evermore.

I enjoyed the exercise of drawing this falcon in flight, and adding the aspect of molt to tell a story. I plan to make this a goal of my illustration, to combine creative imagery with context that communicates ideas and facts about the chosen subject. Of course my ability to do so is still a work in progress itself, but as with learning, the process is ultimately satisfying and something I look forward to for the remainder of my life.