Animal globetrotters

Migration of feathered friends

We humans have gained great mileage in developing hi-tec contraptions (devices), not only to travel the world, but also to space and back, in this modern era.

Yet, our mechanically assisted journeys are put to shame when compared with the journeys undertaken by many of those in the animal kingdom. Long before we homo sapiens became accomplished navigators and explorers, many species of animals were highly skilled at it.

They made amazing long-distance journeys through land, sea and air. Scientists continue to be battled by the great journeys made by animals such as the wildebeests across Africa, Arctic terns from North to South Pole and back again, and whales that voyage from pole to equator.

They travel without any road, sea or aerial maps and yet succeed in finding their way to their destinations. How do they make these fantastic journeys which we know as migration? Let's check out how our animal friends navigate their way through to become such great globetrotters.

Some of you may be familiar with the term 'migration'. In case you do not know what it means, we'll educate you first about what migration is exactly.

Migration is the periodic movement of animal populations from their usual environments to another environment far away, and back again to their own environment. True migration involves both an outward journey and a return journey.

A single round trip may take the entire lifetime of an animal, such as the Pacific salmon. Sometimes the animals make the same trip over and over again, especially birds and mammals.

You may have often heard of birds and insects that migrate. Well, it is not only these two species that undertake these great long-distance journeys. Even mammals, fish and other animals do. So, first we'll check out how our feathered friends navigate the skies in today article.

Bird migration like most other animal migrations, may be done for two reasons for breeding and feeding purposes. There are many different avian species that travel vast distances for these purposes and they all use complex systems of navigation. They rely on their innate (inborn) knowledge and also many external clues to keep them on course when they travel.

Scientists who have studied bird migrations over many years are of the view that one important component at work where migration is concerned, is a bird's innate knowledge. They claim that birds seem to have an inherent basic knowledge regarding the Sun's position during daytime and also, the Moon and certain stars, at night.

What they mean is that the birds use the Sun and Moon like compasses. But, how do they manage when the Sun is hidden by clouds? By polarised light, because birds can see this.

The Earth's geomagnetic force may also be used. It is the common view that all these navigational modes (methods) are governed by the bird's own internal biological clock which detects and responds to both daily and seasonal environmental rhythms.

Experience too plays a role in successful navigation. Adult birds depend on the additional data they have acquired during previous flights to change or modify their routes if necessary.

This added data could be olfactory (of smelling) auditory or visual. For example, the scent of the sea or meadows, certain animal related sounds in areas they fly over, or the infrasonic acoustics (sounds) generated by the wind passing over mountains and high-rise buildings, and also waterfalls. Sometimes the echoes of their own calls too may be a guide.

Landmarks play an important role in bird migration. Drastic changes in some of these visual and topographical features that birds use as landmarks during daytime flying could have an impact on their migratory routes.

If your curious as to how young birds who have never migrated prepare for their first migratory flight, let us enlighten you. They first explore their territory to familiarise themselves with landmarks and other local features. Then, on their return journey they can use these signs to recognise their home territory. This familiarization of the territory is known as piloting.

The champion long-distance traveller

Who do you think takes the award as the greatest long-distance traveller in the avian world? The Arctic tern of course. Did you know that the round trip this small seabird makes totals in excess of 40,000 km (24,800 miles)?

Arctic terns breed (as the name indicates) in the Arctic region, sometimes within 720 km (450 miles) of the North Pole. They experience 24 hour daylight there during the summer. But, as winter approaches, the bird commences on its Marathon flight south.

Travelling from pole to pole, it reaches the Antarctic circle in about three months, (depending on the route), just in time for summer. Once again, it experiences 24 hour daylight here. This journey however does not end here.

The bird has to get back home doesn't it? So, as soon as winter approaches, this remarkable bird heads north again! Therefore, the Arctic tern makes the longest migratory journey than any other creature, and also experiences more daylight than any other organism. Following the Summer Sun, it travels the greatest distance between breeding seasons than any other bird in a single year.

Some bird species travel in large flocks while others do so as small flocks. The red-billed quelea, a relative of the finches is the world's most abundant wild bird with a population exceeding 10 billion. These birds migrate in massive flocks, and a single flock could contain millions of birds.

When a flock of this size depends upon a farmland, they destroy the entire crop in days. For this reason, this bird is often called the 'feathered locust'. Snow geese, white storks, albatross, and flamingoes are just a few of the birds that migrate.

Some birds fly into our country too to escape the winter. Perhaps you have seen some of these feathered beauties in the wild or at bird sanctuaries. Find out about these migratory birds. Their journeys will be full of interesting facts.

We too will bring you more interesting information about migrating animals in our future issues.