On the basis of long-term researches (1972–1987) special approaches to studying of reproduction Asian Dowitcher Limnodromus semipalmatus (Blyth, 1848) – very much a rare species included in the Red data book of Russia are considered. Exact dates of formation of their clutch are necessary for the analysis of features of reproduction of birds. During too time, during field work clutch already being on different stages hatch more often registers. The flotation method allows to calculate precisely enough dates of appearance of the first eggs in any species nests. However data on use of this method at studying Asian Dowitcher in the literature are absent. In this report the special approaches allowing correctly to define date laying of the first eggs in nests of this species are considered and to recover a course of its seasonal reproduction even at rather small amount of the clutch which is on constant control.