Birds

Birds

Birds like mammals are an evolutionary offshoot from the reptiles. They still share a number of reptilian characteristics, such as scales and a lack of true teeth, but they differ from reptiles in particular ways also. Birds make up an extremely successful class of animals known as Aves. Their success can be measured both in numbers of species and the wide range of habitats they have made their home. They can be found anywhere from the equator to the polar regions, from lowlands to mountain tops, on land and on water, underwater, underground, on cliff faces, in caves and in cities. Most species live in woodland or grassland of some kind, but deserts, coastlines and islands are also having to birds, among other places. There are few places where birds are not found at all at some time of the year. For many birds their ability to fly is the secret to their success. It enables them to migrate over the globe to find the best availability of food. In fact, those that can`t fly often migrate to some extent too. The importance of migration is that birds can time their reproduction to suit food abundance and give their offspring a good chance of survival into adulthood.

All birds reproduce by laying eggs, which are usually laid in a nest of some kind. Unlike mammals, female birds are not dis-advantaged by pregnancy and both sexes typically share the workload in terms of incubating the eggs and feeding, protecting and teaching young. Overall this allows for a high rate of reproductive success, so that bird populations can be relatively high. This means that species can afford to lose many individuals to predation, starvation, disease and weather without long- term risk to the species survival. When it comes to food, different birds have adapted to eat most things. There are leaf and grass eaters, fruit caters, seed and nut eaters, nectar eaters, insect eaters, invertebrate eaters, fish eaters, amphibian eaters, reptile eaters, bird eaters and mammal eaters. Then there are those somewhere in between, the scavengers, opportunists and omnivores, happy to consume a variety of foodstuffs, including rotting flesh and refuse discarded by people.