I finally saw the loon I had always dreamed of, but...

Not long ago, I heard that a red-throated loon had come to Dishui Lake in Shanghai. I had never seen a loon before, as they live on the sea all year round and are not easy to see in China, so I excitedly went to look for it with my friends.

But when I arrived at the destination, I didn't feel the joy of "adding new species" (adding new bird species to my bird watching record) at all. The loon was easy to find - it was lying on the shore on its side, with black oil stains on the left side of its body , which formed a sharp contrast with its white abdomen and was very eye-catching. After entering the water, it tried to use its beak to comb the contaminated feathers, but it couldn't clean the oil stains.

Red-throated loons (Gavia stellata) resting on the shore and in the water, with oil stains on their left flanks that are very eye-catching | Liriodendron chinense

Two days later, I went out to sea on a boat in Rizhao, Shandong, and found two more black-throated loons near an island reef. They were also stained with oil . I didn't expect that even though they were dozens of kilometers away from the coast, they suffered the same misfortune as the red-throated loon.

Black-throated loon (Gavia arctica) on the reef, with the black oil stain on its abdomen vaguely visible in the red circle | Liriodendron chinense

What shocked me even more was that just after I left Shanghai, another black-throated loon appeared in Century Park in Pudong New Area, with black oil stains covering its neck and abdomen. Only three days after it was found, the black-throated loon died.

After hearing and witnessing these tragedies, I realized how fragile the loons I had once longed to see were.

Loons, fragile sea creatures

Why do these loons get contaminated by oil? What dangers does oil contamination bring to them? This starts with the living habits and body structure of loons.

Loons are a type of seabird, named for their ability to dive. They breed in northern Eurasia and North America in the summer and fly south to overwinter in the winter. There are a total of five species of loons in the world, four of which spend the winter in coastal areas of China .

Loons are a general term for birds in the genus Loon, family Loon, order Loons. The picture shows the breeding plumage (left) and non-breeding plumage (right) of the common loon (Gavia immer)｜Wikimedia Commons

The loon has a body structure designed for life at sea : a sharp beak for fishing, webbed feet for swimming and diving, and legs that are located at the back of the body to generate strong power when diving. Partially solid bones are more conducive to loons hunting in deep waters. They can dive more than 60 meters underwater and stay underwater for several minutes.

Loons are good at diving to catch food | Matthew Studebaker

But precisely because they live at sea all year round and dive to hunt frequently, loons are easily contaminated by oil floating on the sea surface , which can put their lives in danger.

Birds use feathers to keep warm and waterproof, but oil pollution can damage the feather structure , exposing sensitive skin to air and seawater, causing hypothermia. In severe cases, it can even cause diving birds to lose the ability to fly or float on the water.

Moreover, out of instinct, loons will comb and peck at contaminated feathers , in the process ingesting a variety of toxic substances in the oil, such as benzene and polycyclic aromatic hydrocarbons, which can lead to poisoning symptoms such as visceral failure.

A loon covered in oil | Cape Cod Times

Therefore, once a loon is exposed to oil, it is very dangerous. In the 2010 Gulf of Mexico oil spill, researchers estimated the mortality rate of common loons: even a trace amount of oil would bring a mortality rate of 0% to 60%; if it is a mild oil pollution, the mortality rate is more than 80% .

In addition to marine oil pollution, the survival of loons faces many threats, including habitat loss, acid rain pollution, etc. Lead poisoning is also one of the causes of abnormal death of loons - they swallow small stones at the bottom of the water to help digestion, but they may accidentally eat lead sinkers used for fishing and be poisoned.

X-ray showing a lead weight inside a dead loon | Reference [8]

Oil pollution, a nightmare for seabirds

Not only loons, but other species of seabirds are also vulnerable to oil spills at sea.

Oil pollution not only damages the feather structure of seabirds, but also passes it on to hatching eggs or chicks through adult birds, reducing the reproductive success rate of the entire population. Oil pollution contains a variety of volatile toxic components, which may cause lung diseases if inhaled by seabirds.

A greasy Scoter (Melanitta perspicillata) | Wikimedia Commons

Where does the oil pollution at sea come from? Except for a small amount of crude oil that seeps out of deep-sea strata, the vast majority of oil spills at sea are related to human activities , including sewage discharge, tanker travel, oil spills, coastal facility construction, etc.

Among various human activities, large-scale oil spills from large tankers or drilling platforms can be particularly devastating to local seabirds.

In 1989, the Exxon Valdez oil tanker ran aground in the Gulf of Alaska, leaking more than 11 million gallons of crude oil. Rescuers found more than 30,000 oil-stained seabird carcasses on the beach, and it is roughly estimated that more than 250,000 seabirds died .

Seabirds killed by oil in the Gulf of Alaska oil spill | Wikimedia Commons

In 2010, a blowout occurred on the Deepwater Horizon drilling platform in the Gulf of Mexico. A large amount of crude oil gushed into the ocean from the well, covering more than 2,500 square kilometers of sea surface with oil.

Scientific models estimate that the number of seabirds killed by the oil spill is as high as 700,000 , and the population of many seabirds such as laughing gulls in the Gulf of Mexico has dropped by more than 30%.

Ships fight fires during 2010 Gulf of Mexico oil spill | USCoast Guard

Oil-covered pelicans found after Gulf of Mexico oil spill | Science

Sadly, in an industrial society that is extremely dependent on fossil fuels and petroleum products, marine oil pollution is almost inevitable . From the small divers dying in the park covered with oil to the large-scale deaths of marine life due to oil spills, they are all victims of economic development.

How to rescue natural creatures affected by marine pollution as much as possible and how to minimize the damage to the natural environment caused by oil spills at sea are ecological issues that need to be considered urgently.

★

Let’s go back to the story at the beginning.

A few days after I returned from the sea, another group of companions came to the island. They did not see the two black-throated loons stained with oil that I missed - after all, the home of loons is the sky and the sea, and they may have already flown to other seas.

The good news is that they didn't find any oily loons. In the photos they sent, a black-throated loon was floating on the waves, with the feathers on the lower half of its body as pure white as snow .

Another black-throated diver on the same reef | Coke

I hope that one day in the future, the loons that come to this sea area to overwinter will be able to swim freely on the sea like this one.

References

[1] “Oil-soaked black-throated loon found dead in Shanghai Century Park! Its helpless appearance is “heartbreaking”. Why do similar incidents occur so frequently?” Xinmin Evening News

[2]Winkler, DW, SM Billerman, and IJ Lovette (2020). Loons (Gaviidae), version 1.0. In Birds of the World (SM Billerman, BK Keeney, PG Rodewald, and TS Schulenberg, Editors). Cornell Lab of Ornithology, Ithaca, NY, USA.

[3] https://loon.org/

[4]https://response.restoration.noaa.gov/about/media/why-are-seabirds-so-vulnerable-oil-spills.html

[5]https://www.birdrescue.org/our-work/research-and-innovation/how-oil-affects-birds/

[6]https://www.nationallooncenter.org/about-loons/

[7]https://edis.ifas.ufl.edu/publication/uw330

[8]https://vtecostudies.org/blog/first-documented-lead-poisoned-loon-collected-on-lake-winnipesaukee/

[9]Biology of marine birds[M]. CRC press, 2001.

[10]https://www.science.org/content/article/seabird-losses-deepwater-horizon-oil-spill-estimated-hundreds-thousands

Author: Liriodendron chinense

Editor: Mai Mai

Cover image source: Cape Cod Times

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