author(s)
Musayev AM

abstract
As noted at the work, it was determined that, when compared the calendar period of migratory birds with a degree of illumination, 91 studied species migrate at three degrees of illumination at geographical latitude 40⁰. In the lowest illumination the spring migration of birds begins in 27 species- 29,69%, autumn migration ends in 31 species- 34,0%. Spring and autumn migrations begin and end at two degrees of illumination: spring 33∙10⁴ -53∙10⁴ lx and 33∙10⁴ - 82∙ 10⁴ lx, autumn: 55∙10⁴ -30∙10⁴ lx and 80∙10⁴ -30∙10⁴. On average illumination the spring migration begins and ends in 47 species- 57,65%, autumn in 35 species- 38,46%. Spring and autumn migrations begin and end at two degrees of illumination: in 42 species 53∙10⁴ - 82∙10⁴ lx and in 5 species 53∙10⁴ - 53∙10⁴ lx, autumn 80∙10⁴ -55∙10⁴ lx and 80∙10⁴ -80∙10⁴ lx. At a high degree of illumination spring migration begins and ends in 17 species- 18,68%, autumn in 25 species- 27,48%. In the high degree of light, spring migration begins and ends in two degrees of light: 82-82 ·10⁴ lx and 82-124 ·10⁴ lx, autumn in three degrees 127-80·10⁴ lx; 80-80· 10⁴ lx; 80-55·10⁴ lx; Spring migration begins with the increasing illumination degree from South to North: 33- 124∙10⁴ lx, autumn at a decreasing degree of illumination from North to South 127- 30∙10⁴ lx. The difference at the illumination degrees 1-3∙10⁴ lx is connected with the cloudiness of weather.