Posted on behalf of Jane Qiu
Science journalist Jane Qiu is at the Palmer ecological research station on the Antarctic Peninsula, joining researchers investigating how climate change has affected the region in recent decades. Please check back for her dispatches from the bottom of the world.
Jennifer Blum got an email from KRI94 this morning. KRI94 is a nestling male giant petrel and the message was sent from a satellite tag attached to his back. In the past ten days, Blum, an ornithologist of the Polar Oceans Research Group (PORG), a not-for-profit organization in Sheridan, Montana, and her colleagues have been tracking KRI94’s whereabouts from their small tent office at the Palmer ecological research station in western Antarctic Peninsula through signals relayed by satellites.
KRI94 had been on a foraging trip 300 kilometres south of Palmer and, this morning, flew back to his nest on Kristy Cove, one of Blum’s long-term research sites around the station, to release his mate from the incubation duty. As he clocks in, the team springs into action: it’s time to retrieve the tag and track another bird. At giant petrels’ peak breeding season in austral spring, the researchers – fondly known as “the birders” at Palmer – want to know the foraging sites and duration of as many animals as possible.
I follow the birders into an inflatable boat and we sail across the gentle swell of the South Ocean. A short scramble over the rocky coast of Kristy Cove takes us to a patch of elevated ground. A few giant petrels are nestling on mounds of moss, grass and stones, their grey and white feathers blending perfectly into the stony and mossy ground.
Guided by the satellite signal, Blum and her team members, Marc Travers and Kelsey Ducklow, walk straight to the nestling KRI94. With a 20-centimetre antenna sticking out from a 9-centimetre long rectangular device tethered to feathers on his back, the creature seems nonchalant about the visitors. Travers greets him by gently stroking his small but firm body, while Ducklow carefully replaces the egg with a dummy, to avoid damaging the unborn chick when retrieving the tag.
"As long as the bird thinks the egg is there, he will be calm and stick around,” says Blum. KRI94 struggles and flaps his wings slightly as the researchers remove the tag from his back. The entire process is quick and uneventful. When Ducklow puts the egg back to the bird’s underbelly, he shuffles back and forward a few times until getting into a comfortable nestling position.
Once the tag retrieving mission is accomplished, we sail further east to Shortcut Island. The team quickly locates another male giant petrel identified as SHO109. After replacing the egg with a dummy, they fix the tag on a matt of feather on his back with zipties and tape it firmly around them.
The birders deploy five such satellite tags at a time and track about 50 individual birds – randomly selected from over 600 breeding pairs of giant petrels within a radius of three kilometres around Palmer – over the entire breeding season. For the past 20 years, William Fraser, director of PORG, and his team have been banding and tagging the birds to study their foraging and breeding behaviours and to monitor how they respond to a changing environment.
“The population has been increasing around here,” says Blum. In 1975, when Fraser first started the survey in the region, there were only around 270 breeding pairs. Giant petrels are scavengers, feeding on a variety of diet such as krills, squid and decaying animal parts, and can forage over thousands of kilometers, making them less vulnerable to changes in components further down the food chain.
Environmental changes may also be favouring giant petrels’ survival in the Antarctic, says Fraser. The westerly wind that circles the Antarctic continent has increased in strength, lending a helping hand to seabird species, such as the giant petrel, that depend on the availability of wind for soaring and searching the ocean. In addition, the marked decline of sea ice in the western Antarctic Peninsula in recent decades has led to more open water and, in effect, expanded giant petrels’ foraging habitat, says Fraser.
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