Adaptations of Birds

A bird is a type of warm–blooded vertebrate. Most evolutionary scientists agree that birds share a common ancestor with dinosaurs and many birdlike creatures (if not fully fledged birds) like Archaeopteryx flew in the skies over 150 million years ago.

All birds, even flightless birds, have feathers. Made out of a protein called keratin, feathers consist of a hollow spine with thousands of “barbs” branching out from either side. Feathers regulate body temperature and are used for flight and display.

All birds have beaks. They use their beaks to feed and clean themselves, move objects, and feed their young. Beak shapes vary across species and have evolved over time to suit the feeding style of the bird.

All birds, even flightless birds like ostriches and emus, have wings. Interestingly, there was a single species of bird that didn’t have wings: the now extinct and flightless giant Moa, which was native to New Zealand. 

All birds lay eggs, just like turtles, fish, and insects do. Scientists suggest that this ability evolved in birds because the mother bird’s ability to fly would be compromised if it needed to carry heavy embryos. 

The majority of bird species use flight as their primary form of moving from one place to another. Each species of bird uses flight to suit their needs. Some birds need to fly long distances each year to migrate, some birds use flight to hunt, and some birds use flight to escape from predators or to forage. Bird species have different shaped wings that have evolved to suit their primary flight purpose. 

Some bird species, such as eagles, take advantage of warm air currents to soar. Their large wings provide a large surface area to catch the warm air, minimizing the need for flapping, which can drain their energy. 

Many small birds use a flight technique called bounding. This involves flapping for a time, then folding their wings into their body. Although keeping the wings folded for a short amount of time decreases altitude, it saves the birds energy overall.

Birds such as crows use a flight technique called flapping. During this type of flight, the wings provide thrust with both the downward stroke (where the majority of the thrust is produced) and the upward stroke.

Birds such as some ospreys, kestrel, and all hummingbirds, hover, meaning they can remain in one place in the air. This method is extremely energy taxing, one of the reasons why hummingbirds spend the majority of their time feeding. 

All birds have beaks. The shape of the beak tells a lot about the feeding behavior of the bird. Charles Darwin studied the shape of 15 different species of finches on the Galapagos Islands and compared each shape with the type of food favored by the birds. These observations led to his groundbreaking theory of evolution.

Nectar–feeding birds such as hummingbirds have evolved long, slender beaks ideal for probing deep into flowers. Many of these birds also have long tongues that they use to reach the sugar–based nectar produced by many flowers.

Some water birds such as flamingos and spoonbills have beaks that filter food from the water. These beaks act like a strainer, removing larger pieces of food such as shrimp or algae from the water. 

Water hunting birds such as kingfishers and gannets have spear–shaped beaks. These beaks are streamlined to minimize splash and maximize diving depth when entering the water. This ensures that the birds can quickly dive in and catch unsuspecting fish. 

Many parrots have large, curved, hook–shaped beaks. These powerful beaks can crack open even the hardest of nuts and seeds. Some species with longer beaks also use them to dig insects out of the ground and eat them.

Birds of prey (also called raptors), such as eagles, hawks, and falcons, also have large, curved, hook–shaped beaks. They use their beaks to pierce and tear off the flesh of the animals that they catch for food.

Like beaks, the shape of a bird’s foot can tell us a lot about the environment in which the bird lives, and in some species, it suggests what type of food the bird eats. Thickly scaled skin covers a bird’s feet and protects it from damage that could occur while walking and perching.

The feet of 2 of the largest birds in the world, the ostrich and the emu, have evolved for speed. These strong feet give the birds a strong push, and the claws can be used as an effective defense strategy. 

Most aquatic birds have evolved webbed feet that are used to maximize surface area as they move through the water. Seen in ducks, seagulls, and swans, each of their 3 front toes is connected with flexible skin.

The feet of an eagle and other similar birds like hawks and falcons are used to grasp and carry prey. Long, sharp claws penetrate the skin of their prey, making it very difficult for the prey to escape.

Penguin feet have a unique heat regulation system. Since they lose a lot of body heat from their feet and flippers, special fine arteries in their bodies restrict blood flow to their feet while standing on ice. 

Perching birds, with 3 toes in front and 1 in back, make up over half of all bird species. Some species like woodpeckers have zygodactyl feet (2 toes facing forwards and 2 toes facing backwards), allowing them to grip trees and peck away safely. 

Animals would like to avoid competition for the same resource if possible and several species of birds have evolved to share the same habitat or food by resource partitioning. A great example of resource partitioning is the sharing of a spruce forest by 5 insectivorous warblers in North America. 

Warblers are small birds that feed on insects. During the 1950s, scientist Robert MacArthur was puzzled to find 5 species of warblers co-existing in the same forest, all presumably hunting for the same finite amount of insects. 

MacArthur observed that 1 species of warbler would only hunt in the very top of a conifer tree. Another species avoided competition by only hunting in the tree’s middle section. All 5 species concentrated on different parts of the tree, ensuring little competitive overlap.

The partitioning behavior extended to nesting and raising young. Young chicks need a large amount of food and MacArthur found that these 5 species nested at different times of the year, avoiding the increased competition for food. 

Without resource partitioning, 1 species would dominate and outcompete all of the other species. Resource partitioning increases the overall biodiversity of an area or region and strengthens the chances of a genus surviving a catastrophic event.

Birds play a pivotal role in the larger ecosystem. Like other species, birds contribute to overall population control through predator/prey relationships and the recycling of nutrients. They assist in the reproduction of plant life as pollinators and seed dispersers. 

Many birds help spread nutrients across habitats. Bird droppings can contain vital plant nutrients, and deposits left by large groups of migratory birds form the basis of how well plants grow for the rest of the season.

Birds such as hummingbirds help plants with pollination. Pollen from flowers is deposited on the bird’s feathers, or on its beak, and is then taken to another flower for fertilization while the bird feeds on the flower’s nectar.

Scavenging birds like vultures keep the ecosystem clear of dead, rotting carcasses. In addition, vultures feed on decaying carcasses that other scavengers cannot handle, and the acidic secretions found in their guts can destroy many very harmful bacteria.

Fruit eating birds swallow fruit with seeds inside. These seeds survive the digestion process and are deposited via the bird droppings to a site away from the parent plant. This process allows plants to spread their genetic information further.