I'm just playing tricks, but you treat me like an actor

"Look, the fish-catching cormorant has caught another big fish." Ecological conservationists at Miyun Reservoir observed the first batch of migratory birds returning this year, the cormorants, on the bird island inside the reservoir. It is understood that as of April 15 this year, Miyun Reservoir has welcomed back more than 2,000 migratory birds such as cormorants and herons.

Cormorants are the "雎偶" in the poem "雎偶,在河之洲". They are a kind of water bird that helps fishermen catch fish, so they are affectionately called "鱼鹰" by fishermen. Although they are called 鱼鹰, they are not eagles or raptors, but birds of the family Cormorant of the order Boobies, which are naturally good at underwater operations. The wise working people fully utilized and exerted this characteristic and domesticated cormorants to work for them.

Cormorant fishing in Baiyangdian has become a performance item. Photo: My Neighbor Totoro

If you are in the Jiangnan water town, you may have the opportunity to see cormorants and fishermen fishing together. One episode of the documentary "A Bite of China" also introduces the scene of cormorants fishing on Jianhu Lake: the fishermen rowed the boat carrying the cormorants to the middle of the water and signaled them to go into the water to work. The cormorants turned over and jumped into the water one by one, with very light movements. It won't be long before they appear with big fish in their mouths. Sometimes, if they encounter a school of fish that is difficult to deal with, they will attack it in groups.

Of course, some people may ask, why don't they just swallow the fish, but obediently deliver the fish to the fishermen? The answer lies in their necks. Fishermen usually use some plant stems to weave a collar around the neck of the cormorant to prevent it from swallowing the big fish with its retractable throat sac. Of course, after they complete the task, the fishermen will give them some small fish as a reward.

With the emergence of more and more fishing tools, this traditional fishing model has become less and less common. Some places have slowly transformed it into a commercial model. Many tourists come here and spend money to watch the cormorant fishing show.

Cormorants were originally classified into the order Pelecaniformes, belonging to the family Phalacrocorax. According to the latest World Bird List of the IOC (International Ornithologists Union), the family Phalacrocorax, which once belonged to the order Pelecaniformes, has been made into an independent order, with cormorants as the next family.

The most intuitive impression of the cormorant family is that they have long necks and black bodies. The common cormorant (Phalacrocorax carbo) is almost entirely black, with a green-purple sheen on its head and neck, a yellow-green beak and chin, and a white face and throat.

Every spring, in order to welcome the grand blind date, they will change into breeding feathers in advance, with their faces painted with "blush", their heads and necks decorated with white silky feathers, and white patches on their flanks. The sub-adult birds are dark brown all over, with dirty white underparts. The upper beak is black, the beak edge and lower beak are grayish white, and the webbed feet are black.

Common cormorant, Image source: GBIF

The webbed feet of cormorants are different from those of birds in the order Anseriformes (swans, geese, and ducks). We usually see ducks standing on land with webbed feet between three toes, and the hind toes are degenerated, shortened, or even raised. Cormorants are similar to pelicans, with all four toes relatively well developed and connected by webbed feet. The webbed feet of Anseriformes are called "full webbed feet", while the webbed feet of cormorants and pelicans are called "full webbed feet".

I don't need to tell you what the cormorants love most. I'm sure you all know it. However, in addition to eating fish, they occasionally prey on crustaceans and amphibians. Each time they dive for fish, they dive for about 28 seconds, with an average diving depth of 5.8 meters.

Cormorants are also known as underwater robbers. In 2012, when photographer Jean Tresfon was photographing the migratory frenzy of sardines and herring in South Africa, he witnessed the powerful fishing skills of boobies. He also recorded the situation where cormorants failed again and again and finally attacked the fish in the mouths of boobies. They successfully made up for their technical shortcomings by stealing (open robbery). However, there are always better ways to deal with it. Cormorants are sometimes robbed of food by some heron birds.

Cormorant fishing, Image source: Wikipedia

The breeding season of cormorants is from April to June. They like to build nests in groups. Cormorants distributed along the coast will choose to build nests on rugged cliffs or small islands, while those inland will look for some trees as nesting sites. The density of nests is relatively high, comparable to that of herons. High tree nests are generally layered and three-dimensional, so that space can be fully and effectively utilized. They are very adaptable and get along well with herons, egrets, night herons and some arboreal ducks. It is often observed that the nesting areas overlap.

Since the acidic feces of cormorants are highly corrosive, most trees where they nest will die in about three years. Common cormorants also have the habit of reusing old nests the following year, laying 3-5 eggs per nest, with an incubation period of 28-31 days. Usually older and more experienced parents will enter the breeding grounds earlier than novices to start nesting and laying eggs, so that they can better occupy favorable nesting positions and increase the success rate of reproduction.

Eggs of the common cormorant, Image source: Wikipedia

In the initial stage, the chicks feed on the undigested liquid regurgitated by the parents. As they grow older, they begin to eat solid food (such as fish) brought back from the throat pouches of the parents. Fifty days after birth, the chicks gradually grow full-fledged, and sexually mature in 3-5 years (occasionally 2 years old), and then fly to the breeding grounds to participate in reproduction. The longest lifespan can reach 18 years. Cormorants can be said to be birds that cannot stand loneliness. They nest in groups in spring and summer and huddle together for warmth in winter. There can be up to hundreds of them.

The common cormorant is a bird with a wide distribution range, with a total of 6 subspecies, distributed in North America, Europe, Russia, Siberia, Africa, the Middle East, Asia, India, Southeast Asia, Australia, New Zealand, etc. There is one subspecies distributed in my country, the Eurasian subspecies sinensis can be seen in many places, the main breeding grounds are in the northeast and Qinghai Lake, migrating through central China, wintering in southern provinces, including Hainan and Taiwan, and some cormorants stay in Maipu, Hong Kong all year round, becoming local resident birds.

The common cormorant has a wide distribution range. Image source: GBIF

Review expert: He Jiale, project officer of WWF Northeast Resident Working Group.

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