This science studies the seasonal development of wildlife. Russian is considered the beginning of spring phenology in 1721 when Peter I sent a letter to the favorite Menshikov with the order: "When the trees become raskidyvatsya, then tell them to send us the add leaves weekly on klavshi on paper with the signing of the numbers in order to see where the spring was planned earlier." That's it conducted its first study of phenology in Russia.
In Moscow continuous monitoring of the life of nature are conducted since 1880 on the basis of their A detailed calendar where each phenological phenomena are the average date, and the earliest and latest dates marked for the entire observation period. That's why as a reference, we give phenological calendar Moscow.
I must say that the nature of the calendar revealed a strict rule: whenever started in spring — early or late, the sequence of events in each year and the time intervals between them are the same, with minor variations. Therefore, noting the exact date of a natural event, you can predict when there will be the following.