Matrix model of the Steller's sea eagle Haliaeetus pelagicus population in Sakhalin

A matrix model of population dynamics of the Steller's sea eagle (Haliaeetus pelagicus (Pallas, 1811)) based on the data on productivity and size of the territorial-age groups of the Northern Sakhalin (Russia) in 2004–2007 has been elaborated. A specific feature of the model is that it deals with the lack of direct survival estimations of the age classes. The survival of immatures was estimated by the size ratio of the age groups. For adults, an estimate of survival was obtained from published data on the survival of adult individuals in healthy population of a closely related species. The modelling showed that with the adult survival even as high as 0.95, the total population size would decrease by 0.86% per year or faster. The main cause of the decrease is the predation by brown bears which decreases sea eagle reproduction by 28.4% and to the population growth rate ($\lambda$) dropping by 0,0148 (or 1.48% per year). This damage can only be partially covered by compensative capacity of the population reserve (i.e., by the hypothetical involvement of floaters in reproduction). The conditions under which such a stabilization is possible are discussed.