Thirty-year studies of populations of eight shrew species in the Middle Yenisei taiga have shown that at the late 20th century the population dynamics had a pronounced cyclic character, but in the 21st century cyclic dynamics changed with fluctuating one. The analysis of the dependence of the animal body weight on the population density have revealed that under cyclic dynamics at the peaks of the population, the animal's body weight is significantly higher than that at population decline, i.e., the corollary from the Chitty hypothesis (the Chitty effect) is observed. In populations with fluctuating dynamics such regularity has not been observed.
Keywords: Chitty hypothesis; Yenisei taiga; population dynamics; shrews.