It is a sedentary species although the northern populations undertake big migrations.
The mating season varies geographically, taking place throughout the year and peaking between April and June in the Northern hemisphere. They breed in mixed colonies of 10 - 500 pairs, depending on the amount of surrounding food available.
Although they tend to hunt in shallow waters, cormorants are capable of submerging to over 30m depth, moving through the water with their webbed feet and keeping their wings flat against their bodies. The nests vary from small depressions to platforms with sticks and algae. It is common for them to use the same nests year after year.
Cormorants are threatened mainly by the aquaculture industry and the impact they have on farms. They are also hunted for sport and used as food in some countries such as Iran.