While photographing a vagrant juvenile Green Heron (Butorides virescens anthonyi) along the Boise River in early November, I noticed a behavior I wasn’t aware of for this species. When I would get a bit too close the heron would notice me, stop foraging, and flick it’s tail while it slowly walked away, as if it had a nervous tick.
Tail flicking is a behavior that many species exhibit. A recent study with the Black Phoebe found support for the explanation that tail flicking was a sign of vigilance to predators, a topic I’ve written about here. When the bird flicked its tail, the predator got the cue that the bird was aware of its presence and the predator had lost the advantage of surprise. This seemed to make sense in explaining the behavior of the Green Heron I stalked on the Boise River. Each time it began flicking its tail, I’d let off until it relaxed and continued to forage.
Photo 1. Female Black-capped Chickadee (Poecile atricapilla) with bill deformity.
I recently had the pleasure of spending a few days with my friend Rachel Richardson of USGS trapping birds in the Eagle River Valley of south-central Alaska. We captured a few species such as Black-capped and Boreal Chickadees (Poecile atricapilla and P. hudsonicus, respectively), and Red-breasted Nuthatch (Sitta canadensis). USGS has been trapping in these areas for years with the main focus of monitoring bill deformities, the prevalence of Avian Keratin Disorder, and the prevailing causes of a new found virus, Poecivirus.
The Alaska Science Center of USGS in Anchorage is part of a team of researchers, including the California Academy of Sciences, and the University of California San Francisco that have been investigating the causes of Avian Keratin Disorder for over ten years. Avian Keratin Disorder was first documented in Alaska in the 1990’s by Colleen Handel of USGS who leads the research team at the Alaska Science Center. In an article in Molecular Biology that came out in July 2016 (Zylberberg 2016), the team reports on the discovery of a new virus they termed Poecivirus, which may be responsible for the bill deformities.
Appropriately, the discovery is receiving a good deal of press. Below are a few links to national and international articles that detail the work and the discovery. All are worth a read (or a watch):
Photo 2. Rachel Richardson of the USGS Alaska Science Center holding a female Black-capped Chickadee (Poecile atricapilla) with a bill deformity.
On the day I spent with Rachel in the field trapping birds, we only had one Black-capped Chickadee show up with a deformity. However, the one bird had an interesting story. This female (Photo 1) was first captured in 2015 and had no signs of any deformity. This year she obviously has a developing deformity. Her bill grew 5.1 mm in one year, a 70% increase in length. Whether or not this developing deformity will impact her ability to forage, preen, or even breed and provision young is yet to be determined. There are reports of deformed birds successfully rearing offspring, however it is without question that the deformities present a handicap that will ultimately reduce the individuals fitness.
It is important to track the rates and severity of deformities across the world. Because of this, the Alaska Science Center has developed a submission form for anyone to report their sightings of deformities. Please contribute to this effort and submit details of any sightings of elongated bills, including photos and location along with any other evidence for Avian Keratin Disorder at the following website:
Photo 3. Female Black-capped Chickadee (Poecile atricapilla) with bill deformity.
Below are additional examples of AKD in Chickadees that have been captured as part of the Alaska Science Center’s efforts near Anchorage. These individuals unfortunately have more developed deformities than the chickadee we caught while I was tagging along.
Photo 4. Black-capped Chickadee (Poecile atricapillus) with bill deformity. Photo copyright Rachel M. Richardson.
Photo 5. Black-capped Chickadee (Poecile atricapillus) with bill deformity. Photo copyright Rachel M. Richardson.
Photo 6. Black-capped Chickadee (Poecile atricapilla) with bill deformity. Photo copyright Rachel M. Richardson.
It’s excellent to have a breakthrough and a step forward. However, the problem still remains as well as the daunting task of discovering the correlation between Poecivirus and bill deformities, the causes of both, and what role humanity plays in the prevalence and transmission of either. I’d like to tip my hat to those who have done so much great work on this issue thus far. Keep up the good work.
Referenced Literature
Maxine Zylberberg, Caroline Van Hemert, John P. Dumbacher, Colleen M. Handel, Tarik Tihan and Joseph L. DeRisi. Novel Picornavirus Associated with Avian Keratin Disorder in Alaskan Birds. mBio, July 2016 DOI: 10.1128/mBio.00874-16
The Sharp-tailed Sandpiper (Calidris acuminata) breeds in eastern Siberia and winters in the south Pacific, but a large portion of the juvenile cohort pass through western Alaska on their first fall migration. While I was on the Alaska Peninsula waiting for Bar-tailed Godwits (Limosa lapponica) in September, I got to see a few late moving juvenile Sharp-tailed Sandpipers mixed in with massive Dunlin (Calidris alpina) flocks.
At high tide each day our group would hide in the elymus grass and watch shorebirds come into the high rack line to roost. On one occasion, I noticed the opportunity to photograph a juvenile sharpie, so crept on my belly towards the roosted flock. Once I was close enough to take quality photos, I raised my camera. At the same time the flock took to the air and my chance seemed ruined. I thought it odd though, because the roosting Dunlin are usually tolerant if you are careful and move slowly. I looked around and saw a Bald Eagle passing overhead, which was certainly the reason for the panic. I cursed a bit and looked around to see when the flock might return to roost. As I scanned around, I noticed a lone bird still roosted in the rack line. It was the sharpie, which hadn’t pushed to the air with the Dunlin flock. It’s an interesting note, and something I’ve observed with the few Rock Sandpipers that were associating with the Dunlin flocks as well. On few occasions, the other species opted to stay put despite the flock erupting into flight.
I’d love the opportunity to get to know Sharp-tailed Sandpipers better. Like other birds of the region, the juveniles represent one of the excellent species along the migratory route of the west coast of Alaska that make the place so unique and alluring.
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.
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.
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.
ornithologi.com 