Arctic terns breed on lakes, rivers and tundra and generally return to the same colony each year. Arctic terns mate for life. Their relationship begins with an elaborate courtship ritual wherein the female will chase the male high into the sky and the slowly descend. This is followed by a ‘fish flight’ in which the male will offer fish to the female. The arctic tern’s nest is shallow, unlined scrape. The female will lay a clutch of 2-3 eggs which are pale buff, variously spotted and scrawled with a dark brown camouflage. Eggs are incubated for 20-27 days. Once hatched, chicks are brooded by the adults for the first ten days. Adults will raise one brood a year. The birds reach sexual maturity at 4 years of age.