Common breeding migrant. Inhabits rivers and lakes with sandy, pebbly or saline soil shores and scanty vegetation; and rarer the lakes with reed-beds. In spring arrives in mid-April – early May in small flocks of 5-8 up to two dozen birds. Breeds both in small groups and in large colonies sometimes up to several thousand pairs, often together with Little Terns, waders and gulls; prefers the islands near the shore. Nest is located on the ground in shallow hole without lining or is lined with a few dry blades of grass; but in case of location nest in reed-beds the nest is built from the dry reed leaves and other plants on the heaps of old reed stems. Clutch of 2-3, rare 1 or 4-9 eggs (in last case several females lay eggs in one nest) is produced in the end of May to July. Both parents incubate clutch and care for chicks. Flying juveniles recorded from the end of June. Repeated nesting after loss of first clutches occurs often. Autumn migration begins is early, probably from the end of July. Common Terns leave the most breeding areas until the end of August – mid-September, some birds linger into the first decade of October.
В.К.Рябицев. "Птицы Сибири". Москва-Екатеринбург, Изд-во "Кабинетный ученый", 2014.
