I'd be willing to bet they're there. They'll inhabit most of the US.

Population

The Pennsylvania Game Commission counts active great egret (Ardea alba) nests in every known colony in the state every year to track changes in population size. Since 2009, only two nesting locations have been active in Pennsylvania: Kiwanis Lake, York County (fewer than 10 pairs) and the Susquehanna River's Wade Island, Dauphin County (fewer than 200 pairs). Both sites are Pennsylvania Audubon Important Bird Areas. Great egrets abandoned other colonies along the lower Susquehanna River in Lancaster County in 1988 and along the Delaware River in Philadelphia County in 1991. Wade Island has been surveyed annually since 1985. The egret population there has slowly increased since 1985, with a high count of 197 nests in 2009. The 10-year average count from 2005 to 2014 was 159 nests. First listed as a state threatened species in 1990, the great egret was downgraded to endangered in 1999.

Reasons for Being Endangered

At the turn of the 20th century, many bird species were shot for use, in whole or in part, on women's hats. Great egrets were hunted for their beautiful feathers. By 1917, some doubted the species could be saved from extinction. Plume trade, combined with the popular hobbies of egg and bird collecting, decimated populations of many bird species, leading to enactment of several federal laws to protect migratory, breeding and rare birds in the 1900s, namely the Lacey Act of 1900Opens In A New Window and Migratory Bird Treaty Act of 1918Opens In A New Window. In addition, the National Audubon Society, one of the country's oldest non-profit conservation organizations, was formed around this time and used the great egret on its logo to symbolize the organization's commitment to bird conservation. Legal protection from plume hunting enabled the species to rebound.

Pennsylvania's first documented nesting record was in 1957. By 1990, birds had established three modest colonies here. Today, the main Great Egret Statewide Distribution threats faced by the great egret are habitat loss (flooding of shallow feeding areas as a result of dams, for example), water pollution and disturbance of nesting colonies. Boat traffic also can disturb egrets and boat wakes can wash out the shallow foraging areas.

Pa.gov for more.