Colonial Waterbirds in Galveston Bay
Galveston Bay serves as a major nesting area for many species of colonial waterbirds including herons, egrets, gulls, terns, pelicans, cormorants and others. Colonial waterbirds nest in colonies that range in size from just a few to thousands of nesting pairs. As the name implies, colonial waterbirds require aquatic habitats to complete their life cycle. They rely upon a plentiful food supply found in the open bay, mud flats, and seagrass beds. They also forage in estuarine and palustrine wetlands and in riparian habitats along the shores of local bayous.
Depending on the species, nests may be found in shrubs and trees or on the ground. Nesting sites are often in remote areas such as bird islands, stretches of beach, and riparian forests. The remote nature of nesting habitat helps to protect breeding adults and fledglings from predators and human disturbance. The nesting season in Galveston Bay is February through August.
The reproductive success of colonial waterbird populations is dependent upon the availability of suitable habitat free from disturbance. The following stressors have negative impacts on colonial waterbird populations in Galveston Bay:
- Human disturbance of nesting sites, especially during nesting season
- Habitat loss:
- Erosion of nesting islands due to dredging, vessel wakes, and loss of shoreline vegetation
- Subsidence of nesting habitat and conversion to open water
- Loss of habitat due to conversion of land to human uses (development)
- Mortality of colonial waterbird hatchlings due to predation by red-imported fire ants, coyotes and other animals, and
- Bioaccumulation of contaminants ( e.g. DDT/DDE) in the food web.