Аннотация:According to Shilov‟s concept, intrapopulation heterogeneity is the basis for population homeostasis (Shilov, 1977, 1997). This notion was prevailed in studies of animal behaviour, which boosted in 1960–70, both in natural and artificial groups. One of the first studies using the experiments on house mouse showed the association of individual central nervous system characteristics with behavioural traits in a competition for social rank. It turned out that animals of high rank had stronger type of nervous system and weaker stress reaction. Variation in typological characteristics of central nervous system favoured faster formation of stable relationships in the groups under feebly pronounced aggression (Maslov et al., 1974; Shilov et al., 1974). The first behavioural ranking of free-living birds was done in series of tests on freshly-caught individuals of several species. It was discovered that birds that were more aggressive had lower level of anxiety (Burtt, Giltz, 1973). Further studies conducted by different researchers were mainly based on great tit (Parus major) as an object. They aimed to determine: 1) personality traits and their intercorrelation; 2) the causes of individual variations in behaviour; 3) the influence of behavioural context and the environment on personality performance; 4) the consequences of personality performance. Separation of personality types was based on the reaction of an animal to a novelty (new environment and objects). It was shown that such reaction, rested on different individual susceptibility to the environment (Koolhaas et al., 1999), was not related to sex, age and physical condition of an animal, but correlated with certain characteristics of its physiology, biochemistry, etc. (Drent, Marchetti, 1999; Drent et al., 2003; Dingemanse, Wolf, 2010; Ivankina et al., 2010; Cockrem, 2014; Matthysen et al., 2014). Characteristics of specific personality type were conjugated, e.g. so-called “fast” great tits (proactive type) made more movements than “slow” tits (reactive type) in the open field, and in the aviary with great number of various objects first ones coped with more resources than the latter (Ilyina et al., 2010). The heritable nature of behavioural heterogeneity was demonstrated using artificially selected lines of captive-bred great tits and natural populations (Dingemanse et al., 2002; Drent et al., 2003; van Oers, 2003). In addition, using great tits and coloured flycatchers (Ficedula albicollis), it was shown that individuals of different personality types had significant differences in dopamine-related gene DRD4 (Fidler et al., 2007; Garamzegi et al., 2014). Moreover, they demonstrated that two different intercorrelated behavioural features were associated with two different and certain SNP within this gene. It was the correlation between traits that created possibility to reveal the personality type using simple tests and to approximately predict other characteristics of this type. It is important to separate wide reaction norm from polymorphism (Dingemanse, Wolf, 2010). It turned out that not all tests were equally suitable for work with different species (Morand-Ferron, 2014), therefore developing species-specific complex of tests has a great potential.