Who says dads aren't careful when taking care of their kids? Look at this!

The common tern (Sterna hirundo), also known as Common Tern in English, is very ordinary in both Chinese and English names.

As a typical wetland bird, the common tern is not common in cities and is unknown to most people. When you see it in the wild, most people will just call it a "seagull". Some people observe more carefully and find that "Hey, why does this 'seagull' have a forked tail like a swallow's tail?" This feature is also the reason why terns are called terns.

Common tern foraging for food | Badjoby / Wikimedia Commons

Despite its common name, the common tern is nature's model husband and super dad.

Model husband

Common terns are monogamous birds. When the male is courting a female, he will give her the fish he has caught as a gift. This is common among gulls. If the female is interested in the male, she will accept the gift.

During the egg-laying period and when the female bird is incubating the eggs, the male bird will provide food to the female bird from time to time, and the male bird will also share some of the incubation work. After the chicks hatch, the female bird will spend more time taking care of the young chicks, and the task of providing food at this time is mainly undertaken by the male bird.

Common tern courting | wikipedia

The busy male bird also needs to eat, so it faces a problem of food distribution. In 1979, a paper published in Ornis Scandinavica pointed out that the food provided by male common terns to female individuals is much larger than the food they eat themselves. In other words, the male bird eats small fish himself and gives the partner large fish with more meat.

Having written this, do you think that male common terns are very "warm-hearted" - just like us humans, couples in love usually save good things for each other?

However, in fact, the behavior of male common terns can be explained from a biological perspective. Giving larger fish to female birds can provide more food in a limited number of flights. This strategy can be seen as an optimal foraging strategy, using the most energy-saving method to achieve the best results. Birds are not stupid at all.

Common tern parents and chicks, photographed in Dongying, Shandong | Hu Yunbiao

Careful Dad

Male birds may be more attentive than female birds in caring for their offspring. A paper published in the ornithological journal IBIS in 1986 pointed out that during the brooding period, male birds will provide fish of different sizes according to the growth status of the chicks - as the chicks continue to grow, the fish provided will become larger and larger. Female birds, on the other hand, are not so "considerate" and will give you whatever you like, big or small.

This may be because the female bird consumes too much energy in the egg-laying and incubation stages. The mother bird is already too busy and no longer has much energy to take care of the offspring as carefully as the father bird.

Common terns incubating eggs, photographed in Dongying, Shandong | Hu Yunbiao

Male common terns are not only careful, but also very hardworking. They feed their offspring much more frequently than female birds. If a female bird dies unexpectedly during the brooding period, the male bird is still able to raise the chicks alone. It is really a great nanny.

Feeding Common Terns | Amanda Boyd / US Fish and Wildlife Service Headquarters

The breeding season is fraught with danger

However, although the common terns have hard-working and caring parents, the chicks and eggs still face many crises.

Common terns are ground nesters. Some of their nests are located directly on the bare ground, covered with gravel or dry plants, and some are located at the roots of dry plants. There are usually three eggs in a nest, each weighing about 20 grams, which is about the same weight as two quail eggs. The color of the eggs is mostly khaki with irregular dark spots, which is similar to the background color of the nest, which has a concealing effect. In addition, common terns often breed in groups, which helps to resist predators.

Common tern nest and eggs | Wikipedia

However, even so, common tern eggs and chicks are still at risk of predation by common herons and larger gulls such as the Herring Gull (Larus argentatus).

In addition to predators, ground-nesting common terns are often affected by natural disasters. When there are storms or floods caused by storms, the eggs and flightless chicks of common terns are often washed away or drowned, resulting in "group annihilation". When I was doing a bird survey in Dongying in the summer of one year, I found that after a half-hour rainstorm, the eggs of birds such as white-fronted terns (S. albifrons) on the ground were washed away by the water flow, and some were washed into the stagnant water and "soaked", which basically declared the failure of reproduction.

An individual with a black upper beak and a red base of the lower beak, photographed in Dongying, Shandong | Hu Yunbiao

Fortunately, from a global perspective, the common tern is not currently facing an existential crisis. According to the IUCN's estimate, its wild population is between 1.6 million and 4.6 million, and its endangered category is Least Concern (LC). As long as there is a suitable habitat and enough food, they will be able to reproduce and grow.

What's ordinary about it?

The common tern belongs to the Laridae family of the order Charadriiformes. It has four subspecies, and three of them are distributed in my country.

The nominate subspecies S. h. hirundo is found in Europe and North America. Its beak is red during the breeding season and its tip is black. | Wikipedia

In the eastern coastal areas of my country, I mostly see the longipennis subspecies with black beaks, while in the central and western regions, the beaks of the terns I see are mostly red. When I was investigating in the field, I saw some common terns with black upper beaks and red bases of the lower beaks. I don't know if there is any hybridization between the subspecies.

S. h. longipennis, distributed from eastern Asia to Australia and New Zealand, has a black beak during the breeding season. Photographed in Binzhou, Shandong | Hu Yunbiao

The common tern breeds in the northern hemisphere and winters in the southern or northern hemisphere's lower latitudes, making it a typical migratory bird. Compared to its relative, the Arctic tern (S. paradisaea), which migrates between the Antarctic and the Arctic every year, the common tern's migration range is indeed somewhat unremarkable.

However, the reason why it is called "common" tern is that it has a very wide distribution range. It is distributed on all continents except Antarctica and is found in various coastal and inland wetlands. By the way, among birds, those with the word "common" in their names are usually the most common and widespread in their group, such as the common cormorant (Phalacrocorax carbo), the common merganser (Mergus merganser), the common kingfisher (Alcedo atthis), the common buzzard (Buteo buteo), the common nightjar (Caprimulgus indicus) and the common shī (Sitta europaea).

Common tern, photographed in Binzhou, Shandong | Hu Yunbiao

As someone who has worked with birds, I often imagine myself as a bird to imagine what their lives would be like.

Every year, the common tern travels back and forth between its wintering grounds and breeding grounds. In its life cycle of more than ten years, it repeats the same journey year after year, which seems a bit monotonous and boring. However, the lives of most of us are also like this. As an ordinary bird, the common tern is just like us ordinary people. It is born ordinary, but still lives and reproduces diligently on the earth, writing its own legend.

Author: Hu Yunbiao

This article comes from the Species Calendar, welcome to forward

If you need to reprint, please contact [email protected]