Institute for complex analysis of regional problems of the Russian Academy of Sciences,Far Eastern branch (ICARP FEB RAS), Birobidzhan, Russia

Abstract. It is researched a model of limited homogeneous population size. It is assumed that there is delayed density dependence. It is made the analytical and numerical investigation of the model with different time lag. It is shown there it is the phenomenon of multiregimism. This phenomenon consists in the existence of various dynamic regimes under the same values of parameters. This effect arises in the model that simultaneously possesses several different limit regimes: stable state, regular fluctuations, and chaotic attractor. The research results show if present population dynamics substantially depends on population size of previous years than it is observed quasi-periodic oscillations. Fluctuations with period 2 occur when the growth of population size is regulated by density-dependence in the current year.

Key words: population dynamics, delayed density dependence, mathematical modeling, multiregimism, basins of attraction, dynamics of larch bud moth (Zeiraphera diniana Gn.)