Saturday, June 25

Subarctic Secrets

For nine weeks this summer, I am lucky to have the amazing opportunity to return to work in Churchill, Manitoba, on the western shores of the Hudson Bay. Churchill is situated at the convergence of multiple biomes, with the boreal forest to the south, the low arctic tundra to the north, and Hudson Bay’s inland coastline to the north and east. This subarctic transition zone is characterized by vast, flat swathes of dry, lichen-encrusted tundra, sedge bogs pockmarked with round, shallow ponds, and seemingly endless boreal forest. At about 58 degrees North, the region represents some of the southern-most habitat of its kind, making it an ideal place for arctic research. Our team is here for the same project as last summer: studying breeding and migratory ecology of Hudsonian Godwits for Cornell Ph.D. student, Nathan Senner’s project.

Countless birds come here to rear young and every fiber in their body, every codon in their genome, is devoted entirely to fledging their young. Their nests are their best-kept secrets, and in order to obtain any information, we need to uncover them. This will be the last of five field seasons with the Churchill population, so our main priority is recapturing birds from previous seasons that have been carrying data loggers.

Female Godwit, well-hidden while incubating.

These are tiny light sensors attached to plastic flags on the birds’ legs, which, after being calibrated, deployed on a bird, and recaptured a year later, can tell us that bird's latitude and longitude at any given time, based on the times of sunrise and sunset recorded by the device. From this, we have been able to map the birds’ astounding (and previously unknown) migrations, which take them from the subarctic to Tierra del Fuego (the southern tip of South America) and the Chilean coast in a matter of days. These birds often fly up to 6,000 miles in a single, non-stop flight, sometimes tripling their body weight before setting off for their distant destinations. The recapturing of birds on the breeding grounds to retrieve this data, however, is where things get dicey (see a post from last year for more detail:

Retrieved data logger!

Male Hudsonain Godwit, carrying a data logger.

So far this season, we’ve seen devastatingly high depredation rates in our godwit nests, and are now down to 3 active nests, of 14 originally found, including re-nests of some pairs. One of the concerns is that the delayed snow melt this season, coupled with high water levels in the fen, resulted in godwits choosing the highest (and consequently most exposed) mounds on which to nest. All but a very few of the nests this year have been placed in grass clumps at the tops of high mounds, instead of under the short, tangled branches of a Dwarf Birch on the lower mounds (which was the case for nearly 100% of the nests last year). From above, these nests are much easier to spot, and the birds subsequently have to deal with a broader range of predators. In addition to foxes and sharp-eyed Northern Harriers, the godwits are jumping off their nests to mob Jaegers and Ravens, revealing their eggs to these predators as well. Last year, it was rare to see a godwit leave its nest for anything other than a low-flying, eyes-prying Harrier.

Aside from the near-constant nest-searching, we’ve continued to spend time finding Whimbrel nests and banding and flagging them, as part of the Arctic Shorebird Demography Network’s intensive, pan-nearctic shorebird survey. One of the most amazing things about spending sixty some days in the field in Churchill is having the opportunity to intimately observe the breeding biology of dozens of northern species, many of which are only transient visitors any further south. On Sundays (our day off), I’ve been getting up at 3:00AM to catch the subarctic sunrise at the fen, aiming to capture video of many of the breeders at their nests (details and footage to come soon). These early mornings are truly incomparable. The sun rises very gradually, taking several minutes to fully clear the horizon as it follows a long and low trajectory to finally set just before 11:00. Before leaving to film in the fen one Sunday morning, I watched as this tempered dawn bled across the sky towards the full moon, still sitting against a cobalt twilight in the west, and felt a bit estranged from the familiar confines of a passing day.

Arctic Tern

American Golden-plover

And now, as the days wear on without new nests, and the many wet socks corrode any surface on which they momentarily reside, Sunday couldn’t come sooner. But the longing certainly isn’t for a want of excitement, as we had our fair share yesterday afternoon. The first polar bear this season meandered down Twin Lakes Road, which neatly bisects the fen where we work most days, from north to south. As we approached the road at the end of a long morning, minds numbed from endless nest-searching and eyes drooping, mesmerized by boots sloshing through bog, Hannah looked up to see a bulky mass of white fur lumbering towards the car.

We were split into two pairs, and another team of three (working with Dunlin) was to our south when Hannah radioed to alert us of the bear’s presence. We all began to regroup and make our way south towards our car, but so did the bear, continuing along the road. Just as most of us were nearing the second vehicle, however, another truck started down the road, unaware of the bear, which had just laid down in the willows on the shoulder. The bear was then spooked onto the road, and began running towards our car, and so began the foot race. Soon, five of us were at the car, with the bear still hurrying towards us, while Hope and Hannah were still a few hundred meters out on the fen, paralleling the bear as they quickly moved south towards the vehicle. But the bear wasn’t slowing, and once it got fairly close, Hannah and I, from the south and east, respectively, both fired cracker shells to send the bear in a safe direction. Unnervingly, the bear paid no heed to the loud bangs that detonated nearby, and continued trotting in our direction, along the road. I chambered a lead slug and fired a warning shot to the upper left of the bear, which was far louder than the previous cracker shells, and thankfully sent the bear on its way to the west.

We all regrouped safely, with hearts pounding for the next several minutes. It was certainly one of the most exhilarating moments of my life, and in retrospect, a very good experience to have. After spending nearly three months here now, both this summer and last, we never had any sort of dicey encounter away from our vehicles, and while you know that a bear could show up at any time, in any place, its hard to stay truly vigilant all the time; yesterday certainly served as a very real wake-up call. The situation was one I’ve played over in my head countless times while working in Churchill, but I feel much more prepared in the field now, having actually seen such a situation pan out. And in retrospect, it was comforting to see that this bear, like most, was not in the least bit interested in us, but was simply spooked by a passing vehicle, making for an unpredictable situation. All is well, and we’ll be sure to keep things that way in the coming weeks.

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