HeronsGreat blue heron, USFWS photo by Gary Kramer

Two species of herons frequent aquatic habitats throughout the region, with the great blue heron being more numerous than the green heron. The green heron is migratory while many of the great blue herons are year-round residents in most of the state. The number of great blues may grow during migration and in the winter when birds come south after breeding north of Arizona and New Mexico. The Cattle Egret is an introduced bird which crossed the Atlantic from Africa and arrived on the east coast of the U.S. in the late 1880s.

Great Blue Heron (Ardea herodias) 46 inches long
This large heron can often be seen standing in rivers or streams foraging for food; it spears prey with its sharp bill. It breeds on land, building a stick nest high in the trees, often alongside other great blue couples. They are known to nest regularly on the upper San Pedro river and in riparian areas in Santa Cruz county, and they appear frequently in urban areas where golf courses, artificial lakes and canals provide sufficient food resources. The field marks are an overall grey-blue color with white foreneck with black streaks; the bill is yellow. A breeding adult will have plumes on head, neck, and back. A juvenile has a dark crown and no plumes.

Green Heron (Butorides virescens) 18 inches long
The Green Heron is much smaller with a short, stocky build and a blue-green back and crown, sometimes raised to form a crest. Green Herons usually roost and hunt in areas of dense vegetation, where their green coloring blends inconspicuously with their surroundings. It is believed that the Green Heron uses tools in the sense of dropping twigs, leaves or insects into the water as bait for passing fish. It is a solitary hunter and does not socialize with others of its kind. It will often perch on a branch hanging out over the water as shown in the photo.

Green heron, photo by Gary Kramer, USFWS

Heron photos by Gary Kramer, USFWS

Cattle Egret (Bubulcus ibis) 20 inches
Cattle egret, USFWS photo by Jim RorabaughThe Cattle Egret has crossed the Atlantic and moved across the U.S. The first Cattle Egret spotting in Arizona was in 1966. Unlike other herons, Cattle Egrets usually forage away from water. They are very mobile and adaptable and have colonized the agricultural fields of southern Arizona, although they originally were associated with cattle, devouring the insects disturbed by the movements of the large beasts. These egrets sometimes perch on cattle, but there doesn't seem to be any factual basis for the idea that they pick fleas off their hosts. Foraging for insects in farmed fields seems to be their preferred strategy in southern Arizona. These birds are compactly built with shorter, thicker legs than other egrets as well as a thicker bill. They are believed to be becoming more numerous in Arizona at this time. Photo of Cattle Egret by Jim Rorabaugh, USFWS.

References:

Alderfer, Jonathan (ed.). National Geographic Field Guide to Birds: Arizona/New Mexico . Washington, D.C.: National Geographic, 2006. This handy, really pocket-size (4x6) guide includes most of the birds you're likely to see in Arizona. In addition to a photo, it includes information about behavior, habitat and specific local sites where you are likely to find the bird.

Corman, Troy E. and Cathryn Wise-Gervais (eds.) Arizona Breeding Bird Atlas. Albuquerque: University of New Mexico Press, 2005.

Sibley, David Allen. The Sibley Guide to Birds. New York: Alfred A. Knopf, 2000.