Great White Heron | Johnson Ornithology Lab

The Great Blue Heron (Ardea herodias) is a familiar and widespread species across continental North America. However, in southern Florida, the Greater Antillean islands, and the coastal Yucatán Peninsula, there exists an entirely white subspecies known as the Great White Heron (Ardea herodias occidentalis). Where these two taxa meet in South Florida, they have long been known to interbreed, with the hybrids known as “Würdemann’s Heron” (see photos below). Recent work by McGuire et al. (2019) found that gene flow in these birds is primarily unidirectional, from Great White Heron into Great Blue Heron.

The three forms of Great Blue Heron found in southern Florida. Left, a Great Blue Heron in full breeding coloration, photo by Oscar Johnson. Middle, the hybrid form, "Würdemann's Heron", photo by Michael Todd (ML49120461). Right, a Great White Heron in the Florida Keys, photo by Oscar Johnson.

In the Johnson Ornithology Lab, we are investigating the plumage divergence, ecological adaptations, and breeding success of Great Blue, Great White, and Würdemann’s Herons where their ranges meet in South Florida. This project was spearheaded by undergraduate research student, Rachel Walker, and supported by a grant from the FGCU Seidler Undergraduate Fellowship.

On the left, a foraging Great White Heron at National Key Deer NWR in the Florida Keys. This subspecies is primarily found in sunny tropical saltwater habitats, as shown here. Photo by Oscar Johnson. On the right, a heron colony in Lee County, Florida, showing both Great White and Great Blue Heron chicks on nests. These chicks are all fully grown and near fledging. Photo by Oscar Johnson.

McGuire, H. L., Taylor, S. S., & Sheldon, F. H. (2019). Evaluating the taxonomic status of the Great White Heron (Ardea herodias occidentalis) using morphological, behavioral and genetic evidence. The Auk, 136(1), uky010. https://doi.org/10.1093/auk/uky010