Nature calendar: spring
This year, the spring in Polistovsky Reserve was very early. The thaw, which began in early February, lasted for 13 days and turned out to be not just a temporary warming, but the beginning of meteorological spring. In phenology, this stage is called the “snowy spring”.
Since the 8th of February, maximum air temperatures have steadily crossed 0°С in the direction of increase. In February-March, there were a few brief cold periods, but the long severe frosts could not return to Polistovsky. The winter lasted 75 days this year - from November, 25 to February, 7, and spring came 20 days ahead of the calendar time.
According to Polistovsky Reserve weather station, after the onset of the meteorological spring, the maximum air temperature was + 6.8°С, this value was recorded on February 16 and March 18. Thermometers reached the minimum mark of -13.6°С on the night of March, 2, however the next day the air warmed up to positive temperatures again.
In addition to warming birds behavior indicates the arrival of spring. At the end of February, the first songs of the great tit were hears. In March, migratory birds began to return from the south: starlings, rooks, cranes and swans were seen in the vicinity of the Reserve. Soon lapwings, storks, thrushes, sandpipers, ducks, and passerbirds will join them, and the bogs and rivers of Polistocsky area will be filled with their voices.
The arrival of birds, along with the transition of average daily temperatures above zero from March 14, indicates the onset of the next phenological stage - "motley spring".