Eggs are often only a few centimetres above the water level. Because of the nest location, wind, heavy rains, waves, or flooding can damage the nest or harm the eggs. Nesting materials often change from one year to the next, which explains why black terns move to different marshes in different years. In 1993, black terns nested on the East Amherst Marsh, but they are nesting on the Amherst Point Marsh this year. This border colony of black terns has changed nesting locations many times since they first nested at Tintamarre in 1967.
Black terns have two interesting courtship flights.
At the end of their aerial display, the male follows the female to a perch and feeds her. Both adults incubate the one to five eggs that are laid, which hatch in 20 to 23 days. The chicks can swim, walk, and run by the time they are two days old. If disturbed, thy can hide in vegetation. Terns often lay more eggs if the first ones are lost.