A studio for bird study

Tag: study

Fork-tailed Storm Petrel (Oceanodrama furcata) Foraging on Tidal Flats: Part 2

by Bryce W. Robinson

 

I captured too many images from my recent experience with Fork-tailed Storm Petrels (Oceanodrama furcata) along the Bristol Bay coast of the Alaska Peninsula. Given that our observations warrant a full report in a journal, I’ll maintain some brevity for now. However, I think it is helpful in the interim to share supplementary video and images that set the stage for the publication. The rest will come out with the article sometime in the coming year.

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Stuart Fetty walks towards a resting Fork-tailed Storm Petrel as the tide rises.

We had a few days where the birds lent themselves to close proximity photography. They were all around us, and didn’t seem to understand or comprehend the concept of a terrestrial predator. In one instance, we walked as close as a meter or so to a bird sitting on the water with no response. Whether this was an ill or a healthy bird resting, I can’t be sure. We do however have some indication that these birds were healthy, but these are details that will be discussed in publication.

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Fork-tailed Storm Petrel kiting in an onshore wind. Note the fish carcass in the foreground, an attractant for the birds to this location.

The past six months have been full of unique encounters with bird life in Alaska, and have produced a nice list of potential publications that I’ll be working on throughout the winter. I’ve taken a lot of satisfaction in working in a place where the birdlife is still relatively understudied, a place where paying attention, taking good notes, and diligent photography all support the opportunity to add to our basal knowledge of natural history of the less understood species of North America.

Fork-tailed Storm Petrel (Oceanodrama furcata) Foraging on Tidal Flats: Part 1

by Bryce W. Robinson

Video 1. Dan Ruthrauff photographs passing Fork-tailed Storm Petrel as the tide comes in. Bristol Bay coast, Alaska. September 2016.

Over my time on the Bristol Bay coast near the village of Egegik on the Alaska Peninsula, I was privy to one of the most incredible experiences I’ve ever had with birdlife. The experience is captured in video 1, which shows Dan Ruthrauff kneeling on tidal flats at low tide photographing passing Fork-tailed Storm Petrels at close range. I’d never heard of anything like this for any pelagic bird. It turned out to be a regular occurrence, but still appears quite novel so far as we understand Fork-tailed Storm Petrel foraging behaviors.

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Photo 1. Fork-tailed Storm Petrel arcing down amidst a dynamic soar in high winds. This photo was taken from the shoreline at high tide. Bristol Bay coast, Alaska. September 2016.

Typical experiences with Fork-tailed Storm Petrels are like the image above: A dynamic soaring Hydrobatid at relatively close range. It’s very exciting, but nothing like walking through tidal flats surrounded by the birds.

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Photo 2. Fork-tailed Storm Petrel at rest on the water. I was standing in ankle deep water when this photo was taken. Bristol Bay coast, Alaska. September 2016

Other more typical experiences can provide observations such as the above photo, where calm water and resting birds near a boat might provide great views. Photo 2 is a bird that I stood near in ankle deep water. This bird was taking a moment to rest from foraging and seemed non-plussed by me. I’ve never heard of anything like it.

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Photo 3. Fork-tailed Storm Petrel (Oceanodrama furcata) dabbing on water. I was lying on my belly when this photo was taken. Bristol Bay coast, Alaska. September 2016

The experiences continued for the entire two weeks I was on the Bristol Bay coast. After reading through the literature, the behavior seems undocumented and may warrant publication as a note. I’m excited to organize, avail myself of the literature, and share this experience with a crowd more knowledgeable and literate than myself. For me, experiences like these make field ornithology one of the best things about life.

Red Knot (Calidris canutus roselaari) Fieldwork in Western Alaska

by Bryce W. Robinson

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Adult Red Knot (Calidris canutus roselaari) captured on the breeding grounds in western Alaska.

On 1 July I travelled to Nome, Alaska to work on roselaari Red Knot research. I’ve spent the last month working on the project, and I’ve learned a great deal. The U.S. Fish & Wildlife Service has been conducting research on breeding Red Knots for the last seven years on ridge lines outside of Nome. They’ve focused on reproductive monitoring, marking and resighting birds, and determining the timing of arrival and departure on their breeding grounds. The effort has also provided collaboration with folks studying this population on their migratory and wintering grounds. You can read more about the connectivity study here.

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Red Knot research field station. Seward Peninsula, Alaska

I feel fortunate to have joined the work, especially considering that the collaborative study effort on this circumpolar breeding species is growing. This year a researcher from the Royal Netherlands Institute for Sea Research (NIOZ) joined the USFWS study effort in Alaska. Jan van Gils Ph.D., whose work was recently featured as the cover article in Science Magazine, joined Jim Johnson and Lucas DeCicco and the USFWS crew to investigate the potential impacts that trophic mismatch may pose on the breeding roselaari Red Knot. It was excellent spending time with Jan, as we discussed many ideas concerning climate change impacts on Red Knots and Arctic life alike.

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Jan van Gils et al. 2016 as featured on the cover of Science Magazine.

Alaska’s Red Knot population breeds on higher elevation rocky tundra. Many ridge lines on the Seward Peninsula are important breeding grounds for Red Knots. With climate change comes impacts to prey populations that the Red Knot needs for successful breeding.

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Red Knot breeding grounds in western Alaska. The low rocky ridge lines surrounding the river valleys are the preferred breeding habitat of the roselaari Red Knot.

There is then the potential that the tight timing of arrival and breeding of these birds may no longer coincide with the peak abundance of prey populations, something that has already been shown in many species that breed in the Arctic. Thus, understanding fully the timing of their breeding on the ridge is essential for understanding future climate change impacts.

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Pinpoint GPS unit attached to an adult Red Knot.

To better understand the latter portion of the timing of Red Knot breeding on the Alaskan ridges, Jim and Luke began deploying pinpoint GPS dataloggers on adults to determine when they depart the breeding grounds, the time they spend on migratory stop over sites, and the length of migration, . This year we deployed units that have already started returning data on migratory locations and duration. It will be exciting to see how the birds differ, or don’t.

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Luke checks out the placement of the pinpoint GPS unit on this adult roselaari Red Knot.

I had an excellent month on the peninsula. Apart from learning a great deal about these birds and their breeding ecology, I gained more exposure to excellent bird life in one of my favorite ecosystems. At the end of the season Luke and I shifted our focus to the coastal areas to attempt trapping of staging Juvenile Red Knots for more pinpoint deployment. I’ll highlight the rewards from the effort in my next post. In the end the Red Knot work was the cessation of an excellent summer of Alaskan bird study.

The season was successful thanks to a great field crew apart from Jim, Luke, and myself: Nick Hajdukovich who handled the lead for the first part of the season before Lucas joined in the field, Sarah Godin, Bethany, and Charlie and Linnaea Wright. 

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