|Status: Year-round Resident.||Last recorded on site in 2021|
|1987-1991: Confirmed||1992-1996: Confirmed|
|1997-2001: Confirmed||2002-2006: Confirmed|
|2012-2016: Possible but not likely||2017-2021: Possible but not likely
|The Patuxent web-site provides more general information about this species.|
|At this time of year, this species is expected to be present on site.|
A great blue heron rookery existed in the southwest corner of the lab up until 1990. There were 34 active nests in 1988, and approximately 55 young were produced. In 1991 and 1992 a small number of nests were built in a new rookery in the center of the ring, but these were largely unsuccessful. Nesting began again in 1995 in the center of the ring and has continued ever since, though the number of nests fluctuates considerably from year to year. Since 1992, several usually younger birds have remained on site throughout the winter, taking advantage of the open water around the lab for fishing.
Photographer: Gene Oleynik.