What is a Bird?
Birds are animals that are adapted to life in the air and on land.
. All animals (including humans) need to move from place to place in search
of food and water, to escape enemiesand to find shelter.
. All animals need food and water to provide energy and for growth.
. All animals produce waste.
. All animals need a mate to produce young which are then looked after
(althoughsome species of bird give more care to their young than others).
. Birds are the only animals that have feathers.
. Most birds, but not all, can fly.
. Most build nests in which they lay eggs.
. Many can swim as well as fly and walk.
. Birds are found all over the world, in every kind of habitat.
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How are birds adapted to where they live?
Almost every environment has living things adapted to live in it. In all these environments, many different life forms have developed, each one a response to the challenges of that environment. Any feature which has evolved to equip a plant or animal to live more successfully in its particular environment is called adaption.
Adaptations may be any aspects of a creature’s life – feeding, breathing, moving, breeding and escaping from predators. They can involve both structure and behaviour.
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What is a bird of prey?
Any bird which eats other animals, even the robin feeding on worms and insects, is a predator. However, the term, “bird of prey” is normally used to describe two groups – the vultures, eagles, hawks and falcons, which hunt by day, and the owls, which mainly hunt by night.
These groups are not closely related, but have evolved in parallel to show the same basic characteristics of hooked bills for tearing prey and strong talons for killing, grasping and carrying prey. Otherwise they vary enormously in size, agility, food and behaviour.
How many species?
In the world there are 421 species of birds of prey, 133 of them owls. In Britain, we have only 20 species, 6 of which are owls. Some of these are very rare.
Our smallest bird of prey is the little owl (similar size to thrushes) and the largest is the golden eagle. It has a wingspan of more then 2 metres. There is often a variation in size between the sexes – females are usually larger than males.
What do they eat?
Some birds of prey, such as eagles, kites and harriers, take a wide variety of food, but others are specialists. The honey buzzard feeds particularly on honeycombs and wasp larvae, the osprey on fish and the hobby mainly on insects.
How do they hunt?
Hunting methods are variable. Kestrels hover in search of mice or insects, but owls, kites and harriers fly slowly to and fro over the ground watching for movement, or in some cases, carrion. Sparrowhawks and goshawks dash between the trees looking for birds. The peregrine falcon dives, or stoops, can reach 200 kilometres per hour. This contrasts with the barn owl, which flaps in a leisurely manner, often moving at little more than walking pace, as it searches for voles in meadows.
Click to view a movie clip of a female Hen Harrier returning from the hunt with prey. The movie clip may take a few seconds to download.
What are their special features?
Many birds of prey are specially adapted for particular methods of catching and eating their food, eg
. Ospreys – sharp talons and prickly pads on their feet for gripping slippery fish
. Sparrowhawk – short, rounded wings for manoeuvrability in wooded areas
. Falcons – long, pointed wings for greater streamlining and a higher turn of speed over open country
. Honey buzzard – stiffened feathers on its forehead as a protection against wasp and bee stings
Birds of prey do not digest the bones, fur, feathers, scales or wingcases of their prey. This material is ejected by the bird through the mouth in the form of a pellet. By collecting and analysing pellets it is possible to identify the bird’s food and by collecting pellets regularly from the same area, seasonal variations may be discovered. This is done best when the pellet has been soaked in warm water and gently pulled apart using straightening-out paper clips or tweezers. Hard parts can be brushed clean with a small paintbrush and dried on blotting paper.
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Adaptations of predators
A predator is a hunter of live animals. The creatures that it feeds on are its prey.
Most groups of animals contain predators – well known mammals like lions, foxes and weasels; fishes like sharks; and of course, many birds. Few birds are purely vegetarian. Most common birds at some time will take live animal food. For birds like robins, thrushes and blue tits, prey includes earthworms, snails and caterpillars, respectively. Kingfishers and herons both catch fish but may take other water life, like dragonfly nymphs and frogs.
The most obvious bird predators are the ones actually called birds of prey. These form a distinct group that includes owls, eagles, hawks and falcons. Each predator has particular adaptations, features equipping it for its special way of life. In the case of a predator these adaptations will equip it to detect, hunt, capture and consume its particular prey.
Which of these birds do you think are designed for:
1. swift flight, catching other birds in the air?
2. very slow flight, manoeuvrability and pouncing?
3. catching other birds in the air and manoeuvrability and surprise?
4. slow soaring on upcurrent of air in mountains?
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Adaptations of birds of prey
Birds of prey have large eyes which can magnify over eight times actual size. This is important because their prey pay be distant, very small and well camouflaged.
They have binocular vision-both eyes face forward so that they can focus on the same subject. This three dimensional or stereoscopic sight allows them to judge distances.
Their prey may be moving and they need to judge their strike as accurately as possible.
In the case of owls, their extra-large eyes allow vision in very dim light. They then have to rely on their equally acute hearing.
The flight of birds of prey shows a range of adaptations that enable them to pursue prey effectively. Different wing and tail shapes allow for speed or slow flight, agility, slow soaring or hovering.
Click to view a movie clip of a female Hen Harrier preening and cleaning her talons. The movie clip may take a few seconds to download.
Feet are adapted to seize, grip and crush the prey. The claws, or talons, are long, strong, curved and sharp.
Birds do not have teeth, so they cannot take bites out of things as we do. Many swallow their food whole. On occasions, so do birds of prey. But often, the prey is too large. Curved and hooked beaks can tear off pieces of the prey while it is held in the talons. The pieces are either swallowed or used to feed young.