Apr/10

20

Planes, (Seismic) Trains, and Snow Machines

Megan is doing polar bear field research in Alaska’s North Slope. Read her previous post, Field Note: Like a Heat Wave.

A researcher in the artifical polar bear den

I spent the morning setting up sensitive microphones in the relative warmth of a “polar bear” den, which we dug ourselves. The floor of the den was about 2 meters (6.5 feet) below the surface of the snow. After I relayed the cable to a crew-member, I took a moment and sat on the floor of the den. I admired the construction of the den and the quiet, protected environment that we had created.

A microphone is placed in the artificial den.

For a few minutes, I tried to imagine what it was like to be a female polar bear with my newborn cubs. This isolated den was so quiet! How would it feel to suddenly hear a loud noise through these thick walls? Or, how would a bear respond as she heard the slow approach of a large vehicle? Would she leave? Would she panic? Would she try to quiet her cubs so as not to attract the loud noise closer? The questions I asked myself while sitting in the snow den mirrored the overarching goal of our collaborative research program with Polar Bears International: How does noise from human activities impact denning polar bears?

Megan stays as warm as possible!

Female polar bears that roam the sea ice of the Southern Beaufort Sea during the spring, summer, and fall, den in large proportion along the coastal plain of Alaska’s North Slope. Maternal denning takes place over the winter, and once females enter their dens, they don’t emerge until the spring, when their cubs are mobile and more able to cope with the harsh conditions of life in the Arctic.

Large stores of petroleum also attract industry to the same coastal plain region of Alaska. The logistics of Arctic oil extraction and facilities operation dictate that most activity occurs in the winter as well; when ice roads can be constructed and a thick layer of snow covers the fragile Arctic tundra, facilitating the movement of people and supplies.

This overlap of industry and denning bears has the potential to cause biologically significant impacts that may disrupt successful rearing of polar bear neonates in the den. That said, the protective ice and snow of the polar bear’s den, and strictly enforced federal regulations that require the establishment of buffer zones around known polar bear dens, offer some degree of protection to polar bears during this sensitive period of their life cycle. However, climate change may leave females less able to cope with noise disturbances, as they may not have enough energy stored to respond to noise AND provide cubs with all the nutrition and care they need. And so our current research is focused on measuring the noise received in polar bear dens by passing trucks, fixed-wing airplanes, helicopters, snow machines, and more. (As we have moved through the planning process and logistics needed to orchestrate this parade of vehicles, I often think of my 2-year-old daughter and her obsession with trucks and other vehicles.)

Industry exploration, support, and people-transport in the Arctic requires this spectacular range of vehicles, and each emits its own characteristic noise signature; even people walking through the crisp-dry snow on a quiet day have a distinctive and fairly loud noise signature. Once the set-up of our dens is complete, we will run each type of vehicle on measured transects by, and over, our den-site. The microphones we’ve installed will record the noise that is received in these dens as the vehicles pass. Down the road, we will integrate these noise profiles with the data we’ve collected on polar bear hearing. Together, these data should make it easier for us to understand what it is like to be a polar bear in a maternal den and how she may respond when a plane, helicopter, or snow machine passes by.

Megan Owen is a conservation program specialist for the San Diego Zoo’s Institute for Conservation Research.

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