SWIFT

SWIFT

The swift had an amazing adaptation. It has an aerial way of life. It feed, mates and even seeps on its wings. Therefore migrates half way round the world to follow the warm weather.

The young one sits on the edge of their nest. The urge to fly prepares them also for its first flight. Their adult birds keep flying past them and slightly touch them with their wings. The fledglings can’t resist the temptation anymore and launches itself into space. At first it looks as it almost falls to the ground but then it new wings start to beat and it lift up. They will keep on practising for a few days to harden their muscles and then it will join the others for the great migration to South Africa for the winter.  Once they start on that flight it will not stop until it will come back to the nest as an adult. By the time they returned, which is four years, they covered thousands of kilometres without stopping

This lifestyle of swift is incredible and one off because it feeds on small insects spider which drift in the air around the globe. Millions of aphids, midges and other flies, ants, termites and beetles, plus spiders suspended on strand of gossamer, disperse every summer on air currents which carry them to great heights.

The aerial plankton is a great supply and the swift are taken advantage of it. The swift has evolved a great adaptation and it is believed not other birds have these abilities.

EVOLUTION 

The swift adapted itself to use these great food supplies. It vacuums its prey constantly with the mouth open. The mouth is bigger than its peak. It also has a throat pouch which could hold up to a 1,000 insects and it sues it when it feeds its young. Its long, slender, curved wing are ideal for gliding or turning quickly when it sees insects being carried close by on air currents. The wings are not useful for taking off. Therefore the swift drops itself from a high perch and as it drops down and starts flubbing it wings to get air born. Most probably due to this handicap the swift does not land very often.

MIGRATION

As the young bird flies south it catches constantly insect this is a high protein food. This will replace the energy it has spent. The swift beats its wings rapidly and then glides for a moment giving its muscles the chance to rest. As night falls it does not come down to find a good place to rest. In stead it flies higher and higher to find the air current to glides and most properly sleep during the night.

Since it depends on the constant supply of insects the young bird has to time its migration well. As a matter of fact it lives always in summer time as it flies south. Only a few birds would fly north before they are two or three years old.  Also most of the birds will mate not before they are four yeas old. Swifts are pairing for life.

BREEDING

Now even swift have not chance other than coming down to build a nest. They do mate in the air and then find a suitable nesting place. They usually chose a site under the eaves where there is a gap. They either fly straight into the gap like posting a letter or clamber up the walls into the dark hole. Inside they make a nest of straw, grass, leaves or feathers. They lay two eggs and both parents incubate the nest taking it in shifts of two hours.

RARING THE YOUNG

It is mostly very hot under the sun-baked roof and the adults plus chicks are panting to keep cool. They also play host to a louse fly which is very big. Just to give an idea and comparing it to human scale it would measure 10cm. There are mostly six of them on a swift.  Each louse fly takes 150ml blood each week. In spite of the great loss of blood the swift doesn’t seem to suffer any ill effects.

A bigger danger is when the weather drops in temperature and there are no insects to feed the parents as well as the chicks. Thunderstorms are less problematic because the bird flies around them. Sometimes it has to make a round trip of 80 km. The moment the rain stopped they reappear at the nest with throat pouches full of insects. During a normal day they adult bird brings ten food balls to the nest. Each food ball contains 300 insects and it adds up to 3,000 insects every day.

The chicks will leave the nest after only six weeks. The estimate is that by that time the family have eaten 250,000 insects.

START TO FLY

The young swift has no second chance if it gets the first attempt wrong. It passes from total darkness into bright sunshine. It has to drop and than start flying. If it doesn’t get its timing right it will hit the ground and with short legs has not other chance to take off. It will either starve to death or a predator will have a meal. However, this occurs very seldom since they seems be brilliant flyers. A swift can live for at least ten year or more and will have covered millions of kilometres by time it comes to rest finally.