One of the characteristics of birds is, without a doubt, the shape of their legs. And it is that, among all the anatomical adaptations that birds have, the configuration of their fingers and the shape of their legs will depend on the type of life they lead Thanks to All these specializations, birds have been very successful at an evolutionary level and have allowed them to colonize various habitats, often to places where other animals cannot reach. Likewise, the different trophic guilds (that is, species that occupy the same trophic level and share the same resources) use these anatomical adaptations to have access to food, as well as to move, and at this point the disposition of fingers and legs are a key component.
If you want to know more about the types of bird legs and their characteristics and structure, continue reading this article on our site and we'll tell you everything.
Characteristics and structure of the legs of birds
As we mentioned, the body of birds has various adaptations that allow them to have so much breadth in their lifestyles. In this sense, the legs play a very important role.
The hind limbs are made up of the femur, which is relatively short in most birds. The part of the leg that is visible, that is, the one that does not have feathers, is composed of fused metatarsal bones (homologous with the human foot), forming the tibiotarsus, which is the longest part of the leg. Other bones follow and have also fused to form the tarsometatarsus, where the toes join. Birds have the peculiarity of walking on the tips of their feet due to the configuration of their fingers, so it can be said that they are digitigrade.
Most of them have four fingers, but in some it can be three, the first finger being the hallux. The ostrich (Struthio camelus) is the only living bird that has only two fingers, those that have only three are generally some other ratites such as the rhea, the emu, the kiwis and some shorebirds such as the plovers (order Charadriiformes), among others.
As happens with the legs, the shape of the beaks of birds varies depending on the habits and feeding of each species. If you want to know more, you can consult this other article on our site about Types of bird beaks.
Types of bird legs
The legs of birds can be classified into 5 types, also depending on the type of bird, as we will see later. Depending on the number and arrangement of the fingers, they are counted from the outside and the hallux is taken as the first finger. Within each type, there are highly variable configurations among the different orders and families of birds, each possessing a particular toe arrangement or other distinguishable feature. In addition, the nails or claws in which the toes of the legs end are often reflecting the habits of a bird Next, we will explain the different configurations of the toes and types of feet found in birds.
Anisodactyl Legs
This is the typical configuration of a bird's foot, with four toes in total where the hallux (first toe) faces back and the other three point forward. This arrangement is common in passerines (birds such as blackbirds, tits, sparrows, among others), in pigeons (Columbiformes), hawks (Falconiformes) among many other birds. They have a strong hallux that allows them to perch on branches comfortably.
As a curious fact, you can also consult this other article about Birds that sing at night.
Zygodactyl legs
In this case, they have two fingers forward and two backwards Generally, the fourth finger together with the hallux are the ones that point backward. This foot shape is found in cuckoos (Cuculiformes), woodpeckers (Piciformes), and parrots (Psittaciformes), among others. It is also common in owls (Strigiformes), although it can vary within the group. Species that are climbers, such as woodpeckers, often have curved clawsthat help them to hold on to the irregularities of the tree bark without impairing their ability to perch.
Heterodactyl legs
This setting is rarer. They also have two fingers pointing backwards and two pointing forwards, but in this case the back fingers are the second and the first. This arrangement is present in trogons (Trogoniformes) and also allows them to perch on the branches of trees, where they spend a lot of time perching.
Syndactyle legs
The birds that with this configuration have the middle fingers connected, that is, the third and fourth fingers. This arrangement is similar to anisodactyly, except for the fusion of the fingers, it is typical of kingfishers, bee-eaters, rollers and related (Coraciiformes). Fusion of the three front toes, from the second to the fourth, can also occur, as in the giant kingfisher (Ceryle alcyon). This type of leg allows them to perch on flat surfaces as well as cylindrical ones
Pamprodactyla legs
In this case, the four toes point forward, as in swifts (Apodiformes), including the first toe (the hallux). This arrangement is only present in these birds and is used to hang from branches or structures, since they cannot perch or walk because their legs are very short.
You may also be interested in this other article on Types of swallows - Characteristics and feeding.
Types of legs in birds: other classifications
Other classifications also include the degree of development of interdigital webs that the feet of birds may have.
Anisodactyl legs slapped
In the case of aquatic species, such as ducks, geese, seagulls, among others, they have the three front fingers with digital membranes, that is, they have palmate anisodactyl legs with different degrees of development.
Patas totipalmadas
In other cases, such as pelicans (Pelecaniformes), all toes of the foot are joined by a complete interdigital membrane. These are called totipalmate feet.
Patas semipalmadas or brevipalmadas
Other birds, such as shorebirds, have semipalmate or brevipalmate feet, where the three front toes are partially joined at their bases by a membrane. The interdigital membranes give it, like an oar, greater strength to move during swimming, and the degree of development of the membranes will depend on how dependent each species is on water.
Lobed or scalloped legs
On the other hand, some semi-aquatic birds, such as coots and coots (Gruiformes), have lobed or scalloped feet. They feature a wavy or scalloped membrane that surrounds each finger and they maintain their individuality. This type of leg allows propulsion for swimming and greater balance and gripping surface when moving through flooded terrain.
Lobed or lobed legs
Species such as grebes or macaes (Podicipediformes) have lobed or lobed feet where each toe has an individual membrane with a smooth edge.
On the other hand, other features can also characterize the feet of birds. For example, species with more terrestrial habits have long rear claws with which they avoid sinking into mud, sand or other soft surfaces. And in the case of the jacanas (Charadriiformes), they are characterized by their anisodactyl legs with very long fingers and nails that allow them to move and walk on the surface of aquatic vegetation in shallow bodies of water.
Species such as herons (order Ciconiiformes) have the nail on the third finger as a “comb”, that is, the jagged edges, which is called pectinate claw, like other species such as the barn owl (Tyto alba), also has this type of claw, which in this case is used to groom and maintain the feathers.
