Contents
What are birds?
Birds are vertebrates with double, complete and closed blood circulation. And they are warm-blooded animals.
These animals are provided with feathers, breathe through lungs and lay eggs, because they are oviparous animals.
The skeleton of birds
Birds have a bony skeleton, consisting of two hind limbs, the legs, to move on the ground or to hold on, and two fore limbs, called wings, transformed for flight.
These vertebrates have a very light skeleton, since many of their bones have air inside instead of bone marrow, these are the pneumatic bones.
The skull of birds houses and protects the brain.
Skin of birds
The skin of birds is made up of an impermeable horny layer of keratin. Thanks to this, these animals minimize water losses.
These animals have their skin covered by feathers. Feathers are formations of the epidermis made of keratin that originated throughout evolution from the scales of reptiles.
Where do birds live?
Birds can live in a wide variety of environments.
We find terrestrial birds such as goldfinches, pigeons or vultures; freshwater birds, like wattled jacanas, mallards or grays herons; saltwater birds, like for example penguins, albatrosses or seagulls or brackish water birds, such as flamingos.
Bird adaptations
Birds are vertebrates fully adapted to flight. For this, these animals have:
- Strong but very light skeleton.
- Forelimbs transformed into flying structures or wings.
- Powerful pectoral muscles to powerfully flap the wings.
- Very efficient breathing apparatus to satisfy oxygen demands.
- Highly developed heart to meet the effort involved in flight….
Bird respiration
All birds breathe through their lungs.
Pulmonary respiration is the only system that these animals have to capture atmospheric oxygen and eliminate carbon dioxide from the blood, the waste product of cellular respiration.
Reproduction of birds
Birds are oviparous animals, because females lay eggs from which, after going through an incubation period, the chicks hatch. Their eggs are protected by a hard, calcareous covering named the carapace.
These vertebrates reproduce by internal fertilization.
What do birds eat?
Birds have very varied diets and we can see herbivorous, carnivorous or omnivorous birds, depending on whether their diet contains foods of animal or vegetable origin or of both types.
But birds have other types of diets, much more specialized, and we find granivorous, insectivorous, frugivorous and even nectarivorous birds, when they eat grains or seeds, fruits and flower nectar, respectively.
The mouth of birds does not have teeth, but is provided with a horny beak. The shape of a bird’s beak depends on its diet.
The digestive system of birds shows special compartments, called crop and gizzard, where these animals store and crush food.
More information on other animals
