Do the names Antarctic petrel, Cape petrel, snow petrel and light-mantled albatross sound unfamiliar? That's probably because they are found in Antarctica, where they are known as the "lords" of the sky. They form an indispensable part of the Antarctic ecosystem.

Every morning at eight o'clock, Xu Hongying, a member of the oceanographic team of China's 42nd Antarctic expedition and a doctoral student at the College of Life Sciences at Beijing Normal University, begins her work on the deck of the Xuelong 2, China's research polar icebreaking vessel, holding a long-range zoom camera in her hands and constantly scanning the sea and sky.

Her research project for this expedition is about the operational monitoring of seabirds in the Southern Ocean, which involves observing and recording the species, numbers and geographical coordinates of Antarctic seabirds. This provides valuable basic data and image materials for research on Antarctic bird diversity.

Unlike birdwatching on land, the Xuelong 2 is a mobile oceanographic research platform. The ship is moving, the birds are flying and the sea and observation conditions are constantly changing. For Xu, the bridge and the decks on either side are her laboratory. The wide view allows her to see the sea ahead, the shipping lanes on both sides and the distant sky — one of the best locations on the ship for observing birds.

"The defining feature of birdwatching on the ship is constantly being busy. The ship is sailing and the position of the bird flocks relative to the ship is also changing, so I have to constantly adjust my perspective. At least eight hours of observation a day and walking more than 10,000 steps is the minimum," she said.

Many seabirds in Antarctica belong to the order Procellariiformes, and their similar appearance makes identification difficult, particularly as most of them are not found in the Northern Hemisphere. Before boarding the Xuelong 2, Xu's knowledge of these birds was limited to what she had read in books. Initially, she spent her days observing and comparing her camera shots with those in a book, but after a few weeks, she had become proficient at identifying them herself.

"The wandering albatross is huge, with a wingspan of over three meters. Its wings are long and slender, and it hardly flaps them while flying, soaring for long periods like a glider. The black-browed albatross has a distinct black eyebrow stripe behind its eye, and the snow petrel is entirely white and relatively small, making it particularly conspicuous against the backdrop of the sea," she said, adding that she primarily uses the birds' size, feather colour, beak shape and wing shape for identification.

Effective bird observation involves more than just recording what was seen. Latitude, longitude, observation time, quantity, distance from the observation point and weather are all important data points. After each day's observations, Xu compiles this information into an observation report, which serves as crucial baseline data for Antarctic bird monitoring.

"That flock of Antarctic prions (small petrels) had over 100 birds," said Xu. Birds and mammals occupy the top position in the Antarctic ecosystem's food chain, and their population ecology is closely related to climate and environmental changes in the Southern Ocean. Monitoring these top predators over the long term is crucial for understanding the biodiversity and distribution of Antarctic birds, as well as for assessing the potential impact of human activities and climate change on the region. "What we are doing now is laying the foundation for future research," said Xu.