Along the west coast of North America, egg laying may occur from late winter to early spring (peak usually in March or April but may vary among colonies and from year to year). In southeastern North America, southern populations nest irregularly, usually beginning in late fall and extending through June; northernmost populations nest in spring and summer; intermediate populations nest, somewhat irregularly, in winter and spring. Clutch size averages 2-3. Incubation, by both sexes, lasts about 28-30 days. Young leave ground nests at about 35 days, first fly at 71-88 days; leave nests in mangroves at about 63 days. Some first breed at two years in some colonies (e.g., newly formed ones), possibly not until about four to seven years in stable populations (see Johnsgard 1993). Reproductive success varies with level of disturbance by humans, starvation of young, and/or flooding of nests, but typically the number of young fledged per nest averages one or less. This is a long-lived bird, and reproduction tends to be "boom or bust." Colonies include up to 150 pairs in Trinidad.