A studio for bird study

Tag: ornithology

Field Notes on Nesting Golden-crowned Sparrow

by Bryce W. Robinson

GCSP

Figure 1. Female Golden-crowned Sparrow – Zonotrichia atricapilla.

One of the perks of conducting research on Gyrfalcon’s in western Alaska is the time in the field to experience and study Alaska’s unique and diverse avifauna. I had never found the nest of a Golden-crowned Sparrow (Zonotrichia atricapilla) (Figure 1 & 3) until recently. The nest was at the base of a small willow shrub on a sparsely vegetated hillside dominated by lichen covered tundra. It was constructed of grass, was situated on the ground, and contained five eggs (Figure 2.). The egg color was a greenish blue with reddish brown splotching evenly spaced, but densely concentrated on the broad end of the asymmetrical elliptic egg (Figure 2).

GCSP_nest

Figure 2. Golden-crowned Sparrow nest. Note the Musk Ox guard hair in the bowl of the nest.

One thing I missed in the hurried attempt to photograph the nest and leave quickly was the hair in the bowl. It appears that the sparrow used the coarse guard hair of Musk Ox to line the nest bowl. Nests display the architectural and creative genius of birds. I am fascinated to see materials such as Musk Ox hair used in a nest, particularly in only one section such as the bowl. The area where I found the nest was covered with the fine wool from a Musk Ox, termed Qiviut. Why the bird did not use this fine wool, and chose coarse guard hair is enough to wonder upon.

GCSP

Figure 2. Female Golden-crowned Sparrow – Zonotrichia atricapilla.

While I was investigating the nest, the female remained close. I was impressed by her vigilance. She was anxious to continue incubating her clutch. I took her vigilance as a signal that my presence needed to be short, so I recorded the information I needed and quickly retreated. It’s an invaluable opportunity to be in such a place, where many unique and understudied birds are nesting all around. Truly, I’m in a field lab ripe for study, and I can’t take that for granted.

Notes on Gyrfalcon Molt

by Bryce W. Robinson

Adult Male Gyrfalcon - Falco rusticolus

Photo 1. Adult Male Gyrfalcon – Falco rusticolus

I like to pay attention to molt in birds. There are many aspects of a birds life history that can be reflected by their strategy for feather replacement. A great example is something I’ve been watching with the nesting Gyrfalcons I’ve been working with lately.

Last summer, I noticed something about the molt between male and female Gyrfalcons. While I was entering nests to install cameras in the early nesting period (mostly during incubation), I noticed that males were behind females in their molt progression. Following my initial observation, I started paying closer attention to each bird. I continue to take notes on this, and wanted to share the molt of a pair from a nest I visited recently.

Adult Female Gyrfalcon - Falco rusticolus

Photo 2. Adult Female Gyrfalcon – Falco rusticolus

You can see that the male (photo 1) has just dropped his fifth primary. Falcons generally begin their primary molt at P 4&5 and progress in two directions. The female (photo 2) has dropped her third, fourth, fifth, and sixth primaries. You can see P 4&5 are growing in already.

This illustrates a few simple things in the life of a Gyrfalcon. One, that energetics govern the ability to molt. Two, that male and female Gyrfalcons have different energetic roles and energy budgets during incubation and early brood rearing. They have different roles in the process. These are illustrated by the fact that they differ in the progression of their molt.

Later, the rates even out as both adults need to provision for their growing brood. I hope to get photos of this pair on my next visit to the nest in a few weeks.

Short-eared Owl Wing-clap Flight Display

by Bryce W. Robinson

Breeding flight displays in birds are a blend of the bizarre and the fantastic, a show of a birds talent and specialty in communicating it’s unique ability to portray fitness. The Short-eared Owl is no exception, as a low consistent hoot softly settles on the sky, while the bird flies with deep, moth-like wingbeats. Then, as if in suspense, the bird begins to clap its primaries in rapid motion, falling from the sky. After multiple claps and an appreciable loss of altitude the bird spreads its wings and continues its deep wing beats as before. The wing-clap is displayed in seeming desperation, as if the bird is throwing all caution to the wind to produce the most excellent round of claps for onlooking (or listening) females, and intruding males.

I rarely post videos back to back, but I’m making an exception this time because in the same evening I was privy to both Long-billed Curlew and Short-eared Owl flight displays. Both were “on my list” of behaviors to capture on video, and my excitement for capturing both in one evening is too difficult to quell. So I share…

This bird flew tirelessly. For near an hour, the owl flew in the sky performing wing clap after wing clap, all the while letting out a low consistent hooting barely audible to my ears. What a scene, and such a scene that I encourage anyone in the area of breeding Short-eared Owls to search out the chance to observe this behavior in real time. It’s bizarre, but it is at the top of the list for must see in behavior birding, and for good reason.

In the future I’ll be refining my camera skills and upgrading my lens, all in hopes of getting a more clear documentation of this behavior. For better video quality, click through the video link and watch on Vimeo in HD.

Long-billed Curlew Flight Display

by Bryce W. Robinson

The Long-billed Curlew has a bizarre courtship flight display, not unlike many other members of the family Scolopacidae. The male flies tirelessly in broad undulating circles, broadcasting a mournful whine into the sagebrush strewn hills. Having always been enamored by the spectacle, I made it a goal and was extremely pleased to capture the display on video.

If you haven’t heard of the Intermountain Bird Observatory’s Long-billed Curlew Project, I’d like to use the above video to make an introduction. Long-billed Curlews are facing threats in the west, on multiple levels. For many years now the impacts of landscape change have added stress to nesting curlews. Habitat loss from development, degradation from grazing, ATV recreation, etc. are all causing added stress to the birds ability to reproduce. On top of that, IBO has found that there is an issue with folks shooting curlews. What reasons there could be for shooting a curlew escape me, but it is an issue nonetheless and one that IBO attempts to overcome through education and outreach.

On top of these issues, these birds are facing threats off their breeding grounds as well. Contaminants on the wintering grounds add yet another stress to these birds. IBO has deployed satellite telemetry units on a handful of birds to fully understand their year round distribution and where particular populations may face threats.

Stephanie Coates, an all-star of bird biology, recently started her pursuit of a master’s degree in biology at Boise State University. She is working with IBO on their curlew project, and has started a website to chronicle her work and the work of the field crew. Follow along and check out live viewing of curlew movements via satellite imagery, great photos from the field crews, and more.

Visit curlewcrew.com