Seasonal migration is a phenomenon during which birds travel long distances every year. In this case, flights often occur over deserts. Where, then, do they take water flying over the Sahara? And do they even stop in the middle of the desert?
Causes of Bird Migration
Depending on the lifestyle, birds are divided into several types:
- Nomadic - regularly change their habitat in search of food.
- Sedentary - occupy a certain territory and do not leave its borders.
- Migratory - annually sent to warmer climes in winter, and then returned.
The main reason for migration is not so much the cold as the lack of food in the winter. As soon as the cold sets in, food becomes very scarce or it disappears altogether. The birds have to pack in flocks and go to warmer climes. There they can avoid cold and hunger. This mainly applies to birds for which insects, small rodents, and other animals are the source of food.
Birds are able to notice the approach of winter before humans. They pick up changes in atmospheric pressure and other signals. For this reason, preparations for migration begin in advance. If the summer drags on and the autumn is still warm, the birds linger "at home" for a longer period. But if the cold snap comes abruptly, they immediately fly away to the south.
Where exactly do the birds go?
They prefer warm edges that look as much as ordinary nesting sites. Thus, they do not have to change the diet much. For example, forest birds move to forests, and steppes inhabit the steppes. Migrations are not always long. Some species await the winter in Iceland. Although it is quite cold here, the presence of many hot springs allows the birds to be located nearby. There are almost no snow sources around, therefore, you can easily find food.
What makes birds come back?
The question arises - what makes birds come back if they feel great in warm places? The fact is that so many birds gather at wintering sites that the amount of food is rapidly declining. In any case, the new offspring of food is definitely not enough. If we assume that the birds still remain in the south, several new offspring appear, then soon they will not have enough space for nesting.
Birds return to their native lands in spring. Weather conditions greatly affect the duration of the flight. If the spring is late and you have to fly at a low temperature, the birds are very late. For example, a rook can fly 40 km per hour, but in cold weather it will take the whole day at the same distance.
Interesting fact: many birds route through Africa. Among them are swallows, swans, storks, etc. In particular, storks usually fly over the Sahara. At the same time, they fly from Europe to South Africa, and the total route is about 13,000 km.These birds are included in the list of record holders for flight ranges.
The subtleties of flight
Migration routes are completely different. Not always birds can freely find food during a long flight or a place to quench their thirst. The situation with food is a bit simpler. The fact is that, shortly before migration, the bird begins to eat intensely and gain weight. If you have to fly not too long, the mass gain is 15-25%. With a long and difficult flight, the weight of the bird can increase by 2 times.
As for flights through the Sahara, it was previously believed that they did not make stops in the desert at all. It takes about 40 hours for birds to fly around it completely. However, scientists conducted a number of studies and found that most birds fly only at night. In the afternoon, they prefer to relax. In the middle of the desert there are very few oases where you can quench your thirst. Therefore, birds have to do without water for some time. It turns out that they do not drink anywhere while flying through the Sahara.
The closest place where birds can rest and quench their thirst is Juje National Park, located in Senegal. It is considered the first source of water for birds that crossed the Sahara. The park is visited annually by many tourists. Also, several viewing platforms have been built here so that tourists can watch the birds.
Most often, birds migrate in packs, as it is safer and more convenient. They also choose a clear night as a starting point. It is noteworthy that, for example, quail fly exclusively at night.Other species of birds can fly regardless of day or night (ducks, geese, etc.).
Interesting fact: The flight speed of birds is quite high. Small birds can accelerate to 30 km / h, and larger ones - up to 80 km / h. Some individuals develop speeds of about 300 km / h.
Flight height of migratory birds
The optimum flight height for migratory birds is 1-1.5 km above sea level. It provides them with the ability to move at high speed. The fact is that at this altitude, air flows are characterized by a lower level of resistance. However, birds are able to significantly change the height, then dropping to 100 m, then rising up to thousands of meters, if necessary.
Scientists regularly observe migratory migrations of birds and note the stability of their routes. Surprisingly, birds never go astray. Chicks can choose other places for wintering, but later also move along the route. As a guide, they use natural phenomena: the sun, moon, magnetic field, landscape, stars, etc. However, it was not possible to understand how the birds manage to follow one route so precisely. It is assumed that they are able to memorize the area, and then reproduce previously acquired knowledge.
Birds choose different places for wintering. It all depends on their species, habitat, habitual food and other factors. Most often, storks and other large species cross the Sahara. Before, it was believed that birds did not make stops in the desert, but most of them fly only at night, and during the day have a rest. There are no sources of water in the Sahara.Quench the thirst of birds can only in the nearest park Juj (Senegal).
