Cattle egrets now live in most of South and Central America and some of North America year-round, and throughout North America during the winter. They are naturalized year-round residents of Maryland and the Chesapeake Bay region.
Cattle egrets are an unusual heron in that they prefer to feed in grass rather than water. Whereas most herons are wading birds that feed in shallow water, cattle egrets are often seen in pastures and along roadsides. They habitually follow cattle, tractors, and mowing machines, eating insects that they stir up. They also pick insects off the backs of livestock and are attracted to fires, where they snatch insects trying to escape smoke and flames. Cattle egrets feed on grasshoppers, crickets, spiders, frogs, flies, moths, and other insects. They are highly opportunistic feeders that also feed on mollusks, crustaceans, amphibians, lizards, snakes, tadpoles, mice, and nestlings of various birds. They roost in flocks in trees, often near water.
Starting in the late 19th century, cattle egrets migrated across the Atlantic Ocean from Africa and Asia to South America, and then northward into Central and North Americas.
Males tend to be highly territorial when pairing up with females, but pairs then gather in large colonies to breed. These colonies can consist of a few hundred to several thousand birds. Cattle egrets may build their nests in reeds, bushes, or low trees. Both sexes participate in nest building; the male gathers materials and the female constructs it. Females lay clutches of 2-5 eggs, and incubate them for 23 days on average. After hatching, chicks stay in the nest for the first 3 weeks and are ready to fly after 30 days. By about 45 days, they are fully independent.
Cattle egrets are an abundant and remarkably successful species.
Hancock, James and James Kushlan. The Herons Handbook. NY: Harper & Row, 1984, pp. 142-48.