Cattle Egret

Bubulcus ibis ORDER: PELECANIFORMES FAMILY: ARDEIDAE

IUCN Conservation Status: Least Concern

The short, thick-necked Cattle Egret spends most of its time in fields rather than streams. It forages at the feet of grazing cattle, head bobbing with each step, or rides on their backs to pick at ticks. This stocky white heron has yellow plumes on its head and neck during breeding season. Originally from Africa, it found its way to North America in 1953 and quickly spread across the continent. Elsewhere in the world, it forages alongside camels, ostriches, rhinos, and tortoises—as well as farmers’ tractors.

At a GlanceHelp

Habitat

Marsh
Food

Insects
Nesting

Tree
Behavior

Ground Forager
Conservation

Least Concern

Measurements

Both Sexes

Length: 18.1–22 in
46–56 cm
Wingspan: 34.6–37.8 in
88–96 cm
Weight: 9.5–18.1 oz
270–512 g

Relative Size

Smaller and stockier than a Snowy Egret; larger than a Rock Pigeon.

Other Names

Buff-backed Heron
Héron garde-boeufs (French)
Depulgabuey, Garrapatosa, Garrapatera, Garza de ganado, Garza de vaquèra, Garcita de ganado, Garcilla garrapatera, Garcilla bueyera (Spanish)

Cool Facts

Cattle Egrets are native to Africa but somehow reached northeastern South America in 1877. They continued to spread, arriving in the United States in 1941 and nesting there by 1953. In the next 50 years they became one of the most abundant of the North American herons, showing up as far north as Alaska and Newfoundland.
Cattle Egrets follow large animals or machines and eat invertebrates stirred up from the ground. They will fly toward smoke from long distances away, to catch insects fleeing a fire.
The Cattle Egret has a broad and flexible diet that occasionally includes other birds. In the Dry Tortugas off the coast of Florida, migrating Cattle Egrets have been seen hunting migrating warblers.
Cattle Egrets have many names around the world, usually referencing the grazing animals they team up with to forage. In various languages they are known as cow cranes, cow herons, cow birds, elephant birds, rhinoceros egrets, and hippopotamus egrets.
The oldest Cattle Egret on record, originally banded in Maryland, was at least 17 years old when it was captured and released in Pennsylvania in 1979.

Habitat

Marsh

Cattle Egrets breed in coastal barrier islands, marshes, reservoirs, lakes, quarries, swamps, riverside woodlands, and upland forests. They usually nest in colonies already established by native herons and egrets, and forage in fields with grazing livestock. During spring and fall migration they stop along marine shorelines as well as in farm fields. Some spend winters in the southern United States, mainly in coastal areas where the temperature rarely falls below 40° Fahrenheit. Scattered individuals spend mild winters farther north on both coasts, as far as Washington and Rhode Island. Their North American range is still expanding.

Food

Insects

Cattle Egrets have broad, adaptable diets: primarily insects, plus other invertebrates, fish, frogs, mammals, and birds. They feed voraciously alone or in loose flocks of up to hundreds. Foraging mostly on insects disturbed by grazing cattle or other livestock, they also glean prey from wetlands or the edges of fields that have been disturbed by fire, tractors, or mowing machinery. Grasshoppers and crickets are the biggest item on their menu, which also includes horse flies, owlet moths and their larvae, cicadas, wolf spiders, ticks, earthworms, crayfish, millipedes, centipedes, fish, frogs, mice, songbirds, eggs, and nestlings.

Nesting

Nesting Facts

Clutch Size: 2–4 eggs
Number of Broods: 1 broods
Egg Length: 1.4–2 in
3.5–5.2 cm
Egg Width: 1.1–1.4 in
2.8–3.6 cm
Incubation Period: 22–28 days
Nestling Period: 14–21 days
Egg Description: Pale sky blue to sea green.
Condition at Hatching: Mostly helpless, with dark bluish or greenish skin partly covered with down.

Nest Description

Both sexes build the nest, but the female does most of the construction with materials brought by the male. The nest is a shallow, untidy bowl with a foundation of robust sticks, an upper layer of smaller twigs or vines, and sometimes a lining of soft plant materials. It measures about 7–24 inches across and 2–12 inches deep.

Nest Placement

Tree

The male selects a nest site, which is usually in the top outer branches of a medium to tall tree or shrub in a swamp, marsh, or upland.

Behavior

Ground Forager

The most gregarious of all herons, Cattle Egrets flock all year long and form dense breeding colonies and nonbreeding roosts. Cattle Egrets leave their roost or nesting colony just after sunrise, feed in the morning and afternoon with a rest at midday, and make their return flight an hour before sunset. They fly with their necks folded in an S-shape, and run or walk with a swaying gait while foraging. Each breeding male defends a display territory, and the breeding pairs later defend a nest territory at the same or a different site. They are usually monogamous within each breeding season, with occasional trios of two females and one male. In elaborate courtship displays, the males spread their wings, fan their plumes, and prance from foot to foot. Nest predators include grackles, crows, owls, Cooper’s Hawks, Black-crowned Night-Herons, and fire ants. Fledgling, juvenile, and adult Cattle Egrets may be hunted by Peregrine Falcons, Great Horned Owls, Barred Owls, raccoons, red foxes, and domestic dogs.

Conservation

status via IUCN

Least Concern

Native to Africa and Asia, Cattle Egrets began expanding worldwide in the 1800s and reached North America in the early 1950s. Now established in parts of southern and eastern U.S., their range is still slowly expanding and their numbers are generally stable, according to the North American Breeding Bird Survey. Their rapid spread stems from versatile feeding and breeding abilities, an aptitude for dispersing to new areas, and a changing landscape: they gained foraging habitat as people converted land for livestock production and crops. Cattle Egrets may benefit the livestock industry by eating flies (and on rare occasions, ticks) from the bodies of cattle. They are sometimes seen as a nuisance because their colonies can be large, noisy, smelly, and close to populated areas. They are sensitive to pollution in water supplies and agricultural fields. They accumulate residues of some contaminants in their feathers, leading some researchers to suggest they are a useful species for monitoring levels of environmental pollutants.

Credits

Telfair, R.C. 2006. Cattle Egret (Bubulcus ibis). In The Birds of North America Online (A. Poole, Ed.). Cornell Lab of Ornithology, Ithaca, New York.
USGS Patuxent Wildlife Research Center. 2011. Longevity records of North American Birds.
USGS Patuxent Wildlife Research Center. 2013. North American Breeding Bird Survey 1966–2010 analysis.

Range Map Help

View dynamic map of eBird sightings

Migration

Short-distance to long-distance migrant. Most Cattle Egrets breeding in North America migrate to Mexico, Central America, and the Greater Antilles. Several populations stay in the southern United States. They not only migrate in predictable patterns but also wander erratically and may turn up well to the north of their normal range.

Find This Bird

To find Cattle Egrets, head to agricultural areas near wetlands. These are tropical herons, so your best chances will be in warm parts of the southern U.S. Seeing Cattle Egrets is not difficult once you find the right habitat—they usually walk around in the open, on dry land, as they hunt grasshoppers and other small animals. True to their name, Cattle Egrets often associate with cows and other large farm animals, waiting to strike until the cow disturbs an insect or frog. Sometimes, Cattle Egrets even stand atop cows and horses, making them both easy to spot and easy to identify.

muganyiziblog

Friday, April 3, 2015