Running around, running around! Why are these birds repeatedly testing the edge of danger?

In 2016, Pixar Animation Studios released an animated short film "The Snipe", and many people were charmed by the cute little bird in the animation.

The Snipe | Pixar

Some Chinese sources translate this bird as "Sandpiper", which is incorrect. The film's English name "Piper" is an abbreviation of "Sandpiper", which is a general name for birds in the Scolopacidae family, while the true identity of the protagonist of the animation is a three-toed sandpiper (Calidris alba).

The most adorable thing about this bird is its surfing ability - it runs back and forth on the beach with the ebb and flow of the tide. (Click on the video to see three-toed sandpipers surfing together~~)

Sanderlings running back and forth on the beach | Fisher Afu, licensed material

So why do sandpipers run around chasing the waves and "testing the edge of the waves"?

Running around on the beach

This is actually the unique foraging behavior of the three-toed sandpiper. They want to seize the precious opportunity when the waves recede to eat a quick meal.

The English name of the three-toed sandpiper is "Sanderling", which means "little sand" because people often see it on the beach. When the waves recede, some benthic organisms on the beach will emerge. At this time, the three-toed sandpiper rushes over with small steps to find food on the wet beach; and when the waves hit, they turn back in the opposite direction, and so on. In North America, the three-toed sandpiper likes to feed on a type of animal called "mouse crab", but this type of animal is not common in my country.

Rat Cicada Crab | jkirkhart35, CC-by-sa-2.0

Some populations of sandpipers in the South Pacific have an efficient feeding strategy. In order to eat more during the short period of low tide, they will quickly swallow smaller shells; while slightly larger ones will eat the exposed hatchet feet or water inlets of shellfish. Maybe the meat eaten can grow back - sandpipers cut shells like leeks.

Sanderling: Testing the Edge | Andrew Weitzel, CC-by-sa-2.0

We call the area between the average low tide line and the average high tide line of the ocean the intertidal zone (that is, between the lowest and highest tides), which is an area with extremely rich benthic organisms. When the tide rises, the intertidal zone is flooded by seawater, and the three-toed sandpiper will retreat to the higher supratidal zone. For the sandpiper, this area is called the "high tide habitat", in which the three-toed sandpiper will also feed on some near-water insects. In the breeding grounds of the Arctic tundra, the three-toed sandpiper mainly feeds on insects and plants here.

In the animated short film, the three-toed sander's nest is a pit dug out on the beach, but in fact, the typical three-toed sander's nest is usually located in the gravel and moss area on the tundra, and the nest is padded with moss, lichens, dead grass and leaves.

Sanderling with chicks | © Jeroen Reneerkens

Dr. Jeroen Reneerkens, who studies sandpipers, told me clearly: You will never find sandpipers' nests on the sand by the sea, their nests are far away from the sea! This setting in the short film may be to better construct a story. After all, art comes from life but is higher than life.

What does a “snipe” look like?

Snipe is the abbreviation of the woodcock family. The idiom "the snipe and the clam fight" is well-known to everyone, so the word "snipe" is not unfamiliar to Chinese people, but in many people's minds, there is probably no specific image of snipe. This is a type of small wading bird. The smallest is about the size of a sparrow, and the largest is larger than a pigeon. Snipes have long legs and beaks, which are suitable for activities near the water. They mostly look for food in the water or on mudflats, but snipes have different shapes, feeding depths and food types. There is another type of bird that is a relative of the snipe, generally with a shorter beak, called "shorebirds", and the two are collectively called "shorebirds".

The Black-winged Stilt (Himantopus himantopus) has a very impressive leg length | Charles J. Sharp / Wikimedia Commons

The three-toed sandpiper belongs to the genus Calidris. As the name suggests, it is a bird that likes to live on the seashore. Sandpipers are migratory birds, and many species have migration routes that span more than half the globe. Although sandpipers also rely on other habitats for mid-migration supplies, the intertidal zone carries the largest number and variety of sandpipers, making it the most important refueling station for sandpipers.

A group of small balls | Michel Langeveld, CC-by-sa-4.0

Members of the sandpiper family also have different shapes. The largest, the great sandpiper (C. tenuirostris), is 28 cm long, while the small sandpiper (C. minuta) is only about 13 cm. The critically endangered species, the spoon-billed sandpiper (C. pygmaea), has a spoon-shaped mouth. In fact, it is also a member of the sandpiper family.

The three-toed sandpiper is an outlier among the sandpipers. Most birds have four toes, but the fourth toe of the three-toed sandpiper has completely degenerated and disappeared. However, as a water bird, it does not need the fourth toe to grasp with the other three toes. The fourth toe of other sandpipers is also very small, probably because an overdeveloped fourth toe will affect the fast running on the beach.

The fourth toe of the three-toed sandpiper has degenerated | Xing Xiaotian

The Wandering Sanderling

The three-toed sandpiper is one of the most widely distributed shorebirds in the world. Except for Antarctica, its footprints are almost everywhere in the coastal areas of all continents, and a few individuals also appear in inland areas. In my country, the three-toed sandpiper is mainly a migratory bird, migrating through the eastern coast of my country in spring and autumn, and a small number of individuals will winter in the coastal areas of southern China. Individuals that migrate through my country breed in the Arctic tundra and mainly winter in Southeast Asia and Oceania. The farthest migration distance can reach 100,000 kilometers, which is close to the distance from the North Pole to the South Pole.

The non-breeding feathers and young birds of the three-toed sandpiper are gray and white, while the breeding feathers have red upper parts. In spring, individuals in breeding feathers of varying degrees can be seen simultaneously in the eastern coastal areas of my country.

The amount of red feathers in three-toed sandpipers at different stages of breeding plumage varies greatly | Xing Xiaotian

A few weeks after the birth of the three-toed sandpiper chicks, they will embark on a journey of thousands of kilometers. The short summer in the breeding grounds is about to pass, and here will usher in a long period of ice and severe cold. Starting from August every year, three-toed sandpiper chicks can be seen in the eastern coastal areas of my country.

Unfortunately, in my country, the coastal wetlands that the three-toed sandpiper and other migratory shorebirds rely heavily on happen to be the most densely populated areas with the most frequent economic activities. The intertidal and supratidal zones are facing continued development and occupation, especially the high tide habitats, which have been largely reclaimed or used for other purposes.

After the loss of their original high-tide habitat, oystercatchers can only squeeze on the earthen embankments of breeding ponds to survive high tide | Xing Xiaotian

In order to complete long-distance migration, these shorebirds must replenish food and get rest in time. The loss of resting places makes it more difficult for them to reach their destination safely. Many shorebird species in the East Asian-Australasian Flyway are facing a decline in numbers, and some species are even at risk of extinction.

It is sad to think that perhaps in the near future, these little creatures that travel thousands of miles every year will be far away from us. Of course, there are still many things that can be done now. It is necessary for us to promptly discover some of the most important areas for migratory plovers and sandpipers, carry out effective protection, and artificially construct some high-peak habitats in some areas so that plovers can fully stop and replenish. In this way, we will have a chance to delay the process of these plovers moving away from us, and other waterbirds in the East Asian-Australasian Flyway will also benefit from this.

References

Castro, Macarena, et al. "Diet selection of Sanderlings (Calidris alba) in Isla Guamblin national park in the Chilean fjords." Ornitologia Neotropical 20.2 (2009): 247-253.

Author: Xing Xiaotian BirdSeeker

Editor: pee pee shrimp

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