I want to talk about monitoring for a period of departure of swifts in Moscow.
For observations in his district (Krylatskoye) in the west of Moscow, near the border of Moscow, I noted the disappearance of species of black swift 31 July 2015. This is quite consistent with my expectations. A couple of days earlier, I also noted the disappearance of swifts in the center of Moscow on Suschevsky shaft.
However, on 4 August, we went with her son for a walk in a Moscow park, not far from Krylatskoye. Late in the evening, when we returned home, I suddenly heard the distinctive screech. I looked up and froze. Over the roofs of a huge flock of swifts wound. Such a large number of swifts in the Moscow sky, I had not seen before, I saw a flock is the only time in Kazan, the vernal arrival of swifts.
This map shows two red field - is the point at which the same dates July 29-31, swifts were observed. At the bottom of the card - a green area. At this point, 4 August marked Strizhin pack. Both red spots at the same time no swifts.
So it looks Strizhin flock in the sky in this photo all the black specks in the sky - it's swifts.
It turns out that at the same time in the same city, three observers could tell a fundamentally different data. The observer from the Krylatskoye departure is said to swifts. The observer from the Suschevsky shaft would confirm these data. A supervisor from the area of Fili be informed about large flocks of swifts.
But that's not the most interesting. Until now, it was a fairly remote areas. From Krylatskoye Fili Park more than 5 km from the Praça Fili Suschevsky shaft to more than 8 km, and from the Krylatskoye up Suschevsky shaft - more than 12 km. However, discovering August 4 swifts back in Moscow, I decided to continue to observe particularly near the park Fili, to find out when the birds fly away. August 5, I arrived at the station Bagrationovskaya where it would be possible to reach the park. Near the metro sky was empty and quiet, so I was beginning to imagine what form I will send to the project. Meanwhile, as soon as I go just a few houses, I heard and saw Strizhin screeching birds. It turns out that in Moscow's dense building I was in the range of 200-300 meters can not see birds.
This confirms the importance of the mass of observations of natural phenomena, the timing of departure for birds or flowering plants. It is necessary for the viewer in every yard, if we rely on accurate results!
July 30, I watched a group of black swifts departure is in the Kostroma region in Bui (railway area). This happened at sunset, the weather was clear and calm. Swifts even down to the houses, as it was before, and grouped under the high clouds.
July 31 early in the morning there was no swifts.
On August 1, he appeared in the sky above the houses, another group that makes flyby territory. It houses down again and could not hear their customary "screech". They just circled.
What do they write in different sources about the departure of swifts?
Do Swifts autumn departure date is closely dependent on what duration in a given year was their nesting period and in what time frame it has begun. And since both depend on summer weather conditions, we can say that the timing of the autumn departure of swifts depend on the summer weather, especially on the weather in late May - early June, but not on the nature of the fall. The best summer weather, the earlier nesting swifts, the shorter the cycle of life and the nesting occurs before they fall departure. Interestingly, Swift nests farther north, the later it flies - in the south earlier than in the north. In Switzerland, for example, swifts fly off earlier than in Southern Finland.
Different groups (individuals) Swifts fly off is not usually in the same time and it is always necessary to keep in mind when establishing the date of departure of the autumn. According to observations in England, young swifts fly away as soon as they leave the nest, and the old can stay for a few days. If the weather in July was bad, the parents linger a little longer. Birds whose clutch failed, before the birds fly off successfully hatched chicks. Immature (output of the previous year), do not start nesting swifts usually fly off later slot.