Background
Snowy egrets are medium sized white herons with white plumes throughout their body, black bills, yellow legs and feet. They are partial migrants, with overwintering and year-round resident populations occurring in southern North America and South America. During the 1800’s, New Jersey marked the most northern end of the snowy egret’s range; however, they have since expanded north to Massachusetts since the 1950s ¹¹. During the nineteenth century, these birds were hunted for their long breeding feathers, which resulted in population declines. Their populations have since rebounded through conservation and management efforts.

Snowy egrets arrive in Massachusetts in April, and breeding peaks in mid-May ⁸. They nest in areas of thick vegetation, ranging from freshwater and saltwater marshes to barrier islands; nests are typically located off the ground along outer branches of vines, shrubs, and trees ¹⁰. They feed along lakes, wetlands, marshes, and tidal flats, consuming fish, frogs, crustaceans, and insects ¹⁰.

Snowy egrets are vulnerable to many human impacts. They are threatened by loss of nesting and foraging habitat, primarily through wetland drainage for human development ¹⁰, but also pollution, agriculture, and recreation. Snowy egrets have high daily energetic requirements due to their relatively inefficient flying abilities ⁵. They typically nest in large colonies that are often mixed with other water birds, such as herons. Individuals that nest closer to these colonies have been shown to consume more small prey, and generally have lower energetic demands but are more aggressive towards other birds ⁶.

Climate Impacts
Marsh and wetland habitats are vulnerable to sea level rise and altered hydrology, which will likely impact snowy egret nesting and foraging activities ^1,7. Where marsh and wetland accretion (growth) are unable to keep pace with sea level rise, coastal migratory birds, such as snowy egrets, will be forced to use new areas ³. Existing snowy egret coastal habitat is already highly fragmented due to human activities, and further degradation is expected by climate-induced expansion of invasive species and new pathogens (carriers of disease) ¹³. Projected increases in temperature have already shifted bird distributions northward in coastal Massachusetts ¹², and this trend will likely continue for snowy egrets. In addition, mismatches between optimal environmental conditions and the timing of important life stages is expected to impact a number of migratory bird species, albeit in different and uncertain ways ⁴.