WEBBED BIRD: CHARACTERISTICS, HABITATS AND SPECIES - BIOLOGY - 2024

The webbed bird is an aquatic species that has the toes of the legs joined together by a membrane. This specialized member allows animals belonging to this group to swim and dive efficiently.

The body of these birds has a size between medium and large. The legs are generally short, with three anterior toes connected partially or totally by the integument.

Ducks. Source: pixabay.com

Its diet is based on insects, worms, small fish, crustaceans or bird eggs. Some of these birds, such as swans and geese, also include certain plants in their diet.

Webbed feet are considered a convergent evolutionary trait, since they are found in several unrelated animal species. This adaptation of the legs is a response of the organism to the need to navigate in the different bodies of water and to move on land.

In webbed birds the legs have a greater surface area, which allows them to push a greater amount of water when they swim; in this way the animal can swim with greater strength and speed. On land, these birds can walk on unstable surfaces without sinking, such as on wetlands and sandy beaches.

characteristics

Wings

Most webbed birds have very well developed wings for flight. These forelimbs carry the large and strong feathers, forming a supporting surface that allows the animal to fly.

Many make very long flights. Such is the case of the geese that live in Mongolia, which migrate to India by crossing the Himalayas. This flight is almost 4500 kilometers.

However, not all webbed flies; an example of this is the penguin. Their wing bones are compressed, making them very dense. In addition, the joints are stiff and prevent their movement independently. In this way, the wing becomes a "fin" that drives this animal's swim.

Supraorbital gland

This gland is located on the sides of the nostrils of penguins and other webbed birds. Its function is to remove excess sodium chloride from the bloodstream, which entered the animal by ingesting its prey in the seas or oceans.

Uropygeal gland

The uropygeal gland is located near the tail and is highly developed in this group of birds. The function of this organ is the secretion of an oil composed of diester wax, which is used for grooming.

In addition, this oil has a water-repellent effect, which makes the dense feathers of the web-footed ones become waterproof.

Legs

The legs of these birds are webbed, since their fingers are joined by a membrane; due to this, the surface of the legs increases.

This is favorable, since in that part of your body body heat is exchanged as a product of the countercurrent flow of blood.

Within this group of birds there are two types of legs. In gulls, ducks, and other animals, the three front toes are joined by an interdigital membrane. This type of leg is known as webbed.

In contrast, in pelicans this integument encompasses the 4 toes of the foot; this type is called totipalmeada.

Locomotion

As the surface area of ​​the leg is greater than that of the rest of the birds, the propulsive drag generated by the animal with each leg strike is also increased. This is known as drag propulsion.

Also, some webbed birds move using lift-based propulsion, in which the legs generate an aerodynamic lift. This occurs due to the speed of the water and the angle of the leg during movement.

The vast majority of webbed birds combine these two modes of locomotion in the water: some of these birds can row to swim, additionally propelling themselves with the movement of their wings.

Although most of the time these animals are in the water, with some frequency they move to land to, among other things, reproduce. In this habitat the webbed feet provide better contact with sandy, soft or slippery surfaces.

Habitats

Webbed birds include a great taxonomic diversity, so their habitat is very varied. Because they are water birds, they tend to live in water for most of their lives.

Some inhabit lakes, canals, lagoons and calm river waters, such as the collared duck (Anas platyrhynchos) and the mallard (Anas sibylatrix).

Others spend a long time in the ocean - such is the case of the Georgian potoyunco (Pelecanoides georgicus) -, in the open sea - such as the penguin - or in the Caribbean Sea, where the Antillean petrel (Pterodroma hasitata) lives.

Although this group of birds spends a lot of time in the water, it also tends to occupy land spaces, especially during the laying and incubation of the eggs, in the breeding season and to get some insects from their diet.

For example, the California gull (Larus californicus) builds its nest on the ground, filling it with feathers and vegetation. It feeds on fish, eggs, or insects that it catches while walking through the area or poking around the docks.

Wetlands

One of the most frequent habitats for web-footed birds is the wetland. It is a flat area with a surface that is temporarily or permanently flooded, creating a hybrid ecosystem between the terrestrial and the aquatic environment.

Wetlands include estuaries, swamps, marshes, pipes, mangroves, swamps, and estuaries. Therefore, they are formed in territories where there is salty, brackish or fresh water.

For those migratory web-footed birds - such as the northern swallow duck (Anas acuta) - this ecosystem is very important. There they can rest and feed, which corresponds to part of the necessary physiological recovery in the face of the immense geographical displacement they carry out.

There are five wetland systems, the ecosystems of which will vary according to their geographical location:

Estuaries

They are formed by the area in which the river flows into the sea. Examples of estuaries are muddy banks, deltas, and salt marshes.

Marine

They are those that are not affected by river flows. Coral reefs and littorals are examples of marine wetlands.

Fluvial

They are the result of the overflowing of the rivers, which flood the lands that surround it. Examples are flooded forests, flood plains, and meandering lakes.

Palustres

They are those ecosystems that have water almost permanently throughout the year, such as papyrus swamps and swamps.

Lacustrine

They are areas permanently covered with water, with a very low circulation of these. Some examples are the lagoons and the lakes of volcano and glaciers craters.

Examples of species

Duck

This aquatic bird belonging to the order Anseriforme can inhabit both salty and fresh waters. It spends much of its life in water, for which it is very well adapted.

Its webbed feet help it swim and keep balanced when on the muddy bank of a river. The outer layer of the plumage is completely waterproof.

Ducks can hydroplaning by lifting part of their body out of the water by paddling with their legs. These movements generate forces that allow to overcome gravity.

Seagull

They are seabirds that are part of the order Charadriformes and are medium to large in size. Their fur is generally gray or white, and they may have some black spots on the head and wings. They have a robust bill and the legs are webbed.

These coastal animals mainly feed on crabs, insects, birds, and small fish.

To capture their prey they fish or attack them from the air. They also "dance" with their paws on the edge of shallow water to hunt the animals found there.

Loon

Loons are excellent divers that swim semi-submerged. They use their legs to swim, thus propelling themselves both on the surface and under the water.

The legs are located on the trunk far back compared to other waterfowl. This characteristic makes this species of the Gaviform order have a clumsy walk on land. Its size is large and it has the three front fingers joined by a membrane.

Pelican

This bird is a species of the order Pelecaniforme. Its strong, webbed feet allow it to swim very well.

The uropygial glands, located behind the head, are frequently rubbed, thus collecting a serous secretion that spreads over the plumage to waterproof it.

References

1. World atlas (2019). Why Do Some Animals Have Webbed Feet ?. Recovered from worldatlas.com.
2. Wikipedia (2018). Webbed foot. Recovered from en.wikipedia.org.
3. Lee Hollingsworth (2008). Is there a scientific term for webbed feet in birds ?. Recovered from rspb.org.uk.
4. Segovia-Castillo, A., E. Torres-Burgos, A. Echeverría-García, J. Sosa-Escalante and LJ Morales-Arjona. 2007. Priority Species and Habitat of the State of Yucatan, Mexico: Migratory Aquatic Birds. Secretariat of Ecology, Government of the State of Yucatán. Academy. Recovered from academia.edu.
5. Michael Checkett (2019). Webbd wonders. Duks unlimited. Recovered from ducks.org.