His studies based on museum collections and collaboration with others, notably N. A. Gladkov, resulted in a major six-volume work on the birds of the Soviet Union which was published between 1951 and 1954.
Although interested in birds from a young age, his parents wished that he studied law.
Although he had no formal qualifications in biology, he was well read and was fluent in French, German, Polish, Italian and Swedish.
He was mostly into museum ornithology and was an expert on identification and taxonomy taking a special interest in the birds of prey, especially the falcons.
[1] During the invasion by the Germany, the Moscow University collections were moved to Ashgabat, Turkmenistan.