Swallows are the people's "barometer": if they fly low, it will rain. The omen is 100% correct. The explanation of this fact is quite simple: swallows follow their food - small flying insects.
In fact, swallows do not always fly low, but only before the rain, in cloudy weather. The well-known folk omen - "swallows fly over the ground - towards the rain" - is always confirmed in practice. And in good, sunny weather, swallows flicker high in the sky. They practically live in the air, rarely landing on the ground. They prefer to sit on wires, from where it is easier for them to take off. They even drink swallows on the fly, take sips of water, flying over the reservoir. The fact is that swallows are insectivorous birds, and they feed exclusively on flying insects. In clear weather, streams of warm air rising from the ground lift up all kinds of midges, flies, mosquitoes, gadflies and other winged insects. There they are caught by swallows, feeding themselves and feeding their chicks. Before the rain, the humidity of the air rises, microscopic droplets of moisture condense on the wings of insects, due to which the wings become heavy and it becomes difficult for insects to rise high from the ground. They have to fly very low above the surface of the earth or water, and after them (for their food) swallows also descend. People do not see small insects like midges and mosquitoes, but swallows are clearly visible; This is how the popular omen arose: swallows need a lot of insects to feed themselves, to make up for their own energy losses, and even feed the chicks. Swallows descend to the nest hundreds of times a day, bringing not one, but several insects in their beak. It is understandable why swallows are forced to follow insects: midges high in the air and swallows high, midges low and swallows above the ground. Swallows' nests are located in places from where birds can easily fly into the air: in cliffs, steep slopes of ravines or under the roofs of houses. Feeding on flying midges, swallows, of course, cannot winter with us and in early autumn they fly to the south, to Africa and South Asia.
