A concept about ecological significance of biological signal field in mammals proposed by N.P. Naumov (1971) is discussed. The term "biological signal field" means the totality of optical, acoustic, and other physical and chemical phenomena associated with living organisms of the same habitat. The are combined in time and in space in a special way and have informative (signal) and biological importance. The characteristic features of the vital activity, transmitting from generation to generation, are of special significance. They are considered as long-living signals - a mechanism relating different generations. Biological signal field is a specific and powerful ecological factor performing several functions: (1) organizes spatial activity of animals; (2) transmits information about the spatial structure of populations and their use of the territory; (3) organizes and supports the stability of ecological systems.