Bubulcus ibis

The cattle egret, due to its great range expansion in association with cattle ranching, has become a true 'cosmopolitan' species. It occurs in North America, generally not in the west or far north; and Eurasia, though usually not in the east. It also inhabits Africa, Australia and parts of South America. Cattle egret are native to Africa and southern Spain. (Hancock and Elliott, 1978)

Biogeographic Regions: nearctic (Introduced ); palearctic (Introduced , Native ); oriental (Introduced ); ethiopian (Introduced , Native ); neotropical (Introduced ); australian (Introduced ); oceanic islands (Introduced )

Other Geographic Terms: cosmopolitan

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Breeding

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

W Palearctic, Africa, North and South America.

Global Range: (>2,500,000 square km (greater than 1,000,000 square miles)) BREEDS: in Western Hemisphere locally from California, southern Idaho, Colorado, North Dakota, southern Saskatchewan, Minnesota, Wisconsin, southern Ontario, northern Ohio, and Maine south, primarily in coastal lowlands, through Middle America and West Indies to South America (northern Chile, northern Argentina, southeastern Brazil). Breeding range is expanding with deforestation in Central America. NORTHERN WINTER: throughout much of breeding range, north to the southern U.S. In the U.S., most abundant in winter in Florida, around the Salton Sea (California), on the coastal plains of southern Texas, and around the mouth of the Mississippi River in Louisiana (Root 1988). Introduced in Hawaii. Old World species that has spread from populations introduced in South America (NGS 1983); some have concluded that the species colonized South America on its own.

The Cattle Egret (Bubulcus ibis) is an Old World species that colonized northeastern South America from Africa in the 1870s and 1880s (although it may not have actually established until decades later), spread to Florida by the 1940s or 1950s, and reached California by the mid-1960s. More recently, it has colonized the Australasian region. In the Western Hemisphere, the Cattle Egret breeds locally from most of the United States (and adjacent Canada) south (mainly in coastal lowlands) through Middle America, the West Indies, and South America (including Trinidad and Tobago and the Galapagos Islands) to northern Chile and northern Argentina; in southern Europe, it breeds from the Mediterranean region east to the Caspian Sea and south throughout most of Africa (except the Sahara), including Madagascar and islands in the Indian Ocean. In Southeast Asia, it breeds from India east to eastern China, Japan, and the Ryukyu Islands and south throughout the Philippines and East Indies to New Guinea and Australia. In the New World, Cattle Egrets winter throughout much of the breeding range from the West Coast, Gulf Coast, and Florida in the United States south through the West Indies, Middle America, and South America. In the Old World, they winter from southern Spain and northern Africa south and east through the remainder of the breeding range in Africa and southwestern Asia and from southern Asia and the Philippines south through Indonesia and the Australian region. The Cattle Egret was introduced to the Hawaiian Islands in 1959 and is now established on most of the larger Hawaiian Islands. The Cattle Egrets in Asia and Australia are sometimes treated as a distinct species, the Eastern Cattle Egret (B. coromanda), separate from the Western Cattle Egret (Bubulcus ibis).

Unlike other herons and egrets, this species typically feeds in dry fields, often following cattle or other grazing animals and waiting for them to flush insects. It also occurs in other open habitats, including aquatic ones. It nests in low trees and shrubs in mixed colonies with other species of herons and egrets. When associated with grazing cattle in fields, Cattle Egrets feed mainly on large insects flushed by the cattle, but in other situations they may eat crayfish, earthworms, snakes, nestling birds, bird eggs, and sometimes fish. They may also scavenge for food in garbage dumps. Although often associated with cattle or horses in North America, on other continents Cattle Egrets may follow elephants, camels, zebras, deer, and other grazers. They may also follow tractors and lawnmowers.

Cattle Egrets usually first breed at 2 to 3 years of age. The male establishes a pairing territory in or near the colony and displays there to attract a mate. Displays include stretching the neck and raising plumes while swaying from side to side, making short flights with exaggerated deep wingbeats. The nest site is typically in a tree or shrub in a heron rookery on an island or in a swamp. The nest is built mainly by the female using materials collected mainly by the male. It is a platform or shallow bowl of sticks, often with green, leafy twigs added. The typically 3 to 4 (range 1 to 9) eggs are pale blue. Incubation is by both sexes for 21 to 26 days. Young are fed by both parents (by regurgitation). The young begin to climb around near the nest at around 15 to 20 days, to fly at 25 to 30 days, and become independent around 45 days.

Cattle Egrets are strongly migratory. Birds from northern breeding areas in North America may winter to the West Indies, Middle America, and northern South America. In the United States, they are common year-round in Florida, along the Gulf Coast, and in parts of the Southwest. Young birds may disperse great distances, even thousands of kilometers.

(Crosby 1972; Maddock and Geering 1994; Kaufman 1996; AOU 1998; Dunn and Alderfer 2011)

"A stocky white bird often seen in grasslands and paddy fields, accompanying cattle and other large mammals, catching insects and other small vertebrates disturbed by these animals. During the breeding season it aquires orange - buff coloured plumes on the back, crown and crown."

"A snow-white lanky bird, very similar in non-breeding plumage to the Little Egret, but recognisable by the colour of its bill which is yellow not black. In the breeding season it acquires delicate golden-buff hair-like plumes on head, neck and back. Sexes alike."

The cattle egret is a medium sized bird, with a 'hunched' posture, even when it is standing erect. In comparison to other egrets, it is short-legged and thick-necked. The total length of the bird ranges from 46-56 cm, and its wingspan averages 88-96 cm. The basic plumage of the adult of both sexes is pure white, with a dull orange or yellow bill, and dull orange legs. For a brief period of time during the breeding season, however, the plumage of the breeding adults is buffy at the head, neck and back, and the eyes, legs and bill are a vivid red. Because of this coloration, it is sometimes called the Buff-Backed Heron. (Telfair, 1994; Hancock and Elliott, 1978;   http://www.coos.or.us/~aigrette/ce.htm;   http://www.mbr.nbs.gov/id/htmid/h2001id.html)

Average mass: 220 g.

Length: 51 cm

Weight: 338 grams

Cattle egrets generally attain a length of 46-56 cm, a wingspan of 88-96 cm, and a weight of around 360 g (Scott, 1987).

"B. i. ibis (Linnaeus, 1758) B. i. coromandus (Boddaert, 1783) B. i. seychellarum (Salomonsen, 1934)"

Another common Florida egret, the snowy egret (Egretta thula), is somewhat similar in appearance, but it is taller and the bill and legs are black in adult specimens. The legs and the wingspan of snowy egrets are also longer than those of B. ibis (Peterson 1980, Hilty and Brown 1986).

Habitat and Ecology

Systems

• Terrestrial
• Freshwater

The cattle egret is the most terrestrial heron, being well-adapted to many diverse terrestrial and aquatic habitats. Though it does not depend on aquatic habitats to survive, it does make frequent use of them, even when they are not close to livestock-grazing areas. It is also well-adapted to urban areas. In its breeding range, which is similar to its winter range, it often nests in heronries established by native ardeids. (Telfair, 1994)

Terrestrial Biomes: savanna or grassland ; forest ; rainforest ; scrub forest

Comments: Wet pastureland and marshes, fresh water and brackish situations, dry fields, agricultural areas (especially irrigated ones), garbage dumps. In West Indies, roosts at night in mangrove swamps or on mangrove islands (Raffaele 1983). Nests in trees on islands in lakes; along watercourses; in swamps; on mangrove cays; near marshes. Usually nests with other herons or in single species colonies.

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: Yes. At least some populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: Yes. At least some populations of this species make annual migrations of over 200 km.

Northern populations in North America are migratory; move north February to April or later, migrate south September into November. Extensive post-breeding dispersal in all compass directions July to early September in north (Palmer 1962).

It has been calculated that an individual cattle egret can obtain up to 50% more food and use only two-thirds as much energy catching it by associating with cattle, as well as with other large ungulate species. Thus it is a very opportunistic and non-competitive feeder. It commonly associates with livestock, wild buffalo, rhino, elephant, hippo, zebra, giraffe, eland, and waterbuck. Due to their practice of perching on these animals' backs, cattle egrets are often grouped incorrectly with 'tick-birds.' In Australia, they have also been observed to associate with horses, pigs, sheep, fowls, geese, and kangaroos. In the Carribean they even follow the plough, capturing exposed earthworms. The cattle egret's major prey is active insects which are disturbed by the grazing activities of the cattle egret's host animals. It eats mostly grasshoppers, crickets, spiders, flies, frogs, and noctuid moths. It is a very active forager, usually feeding in loose aggregations of small or large flocks of mixed sex and age, varying from tens to hundreds of individuals. It may forage in smaller groups or singly. When feeding, it usually walks in a steady strut, followed by a short dart forward, and a quick stab. If they prey animal is small, it is immediately swallowed. If it is larger, it may be jabbed or dipped in water a few times, but it is not dismembered. (Telfair, 1994; Hancock and Elliott, 1992)

Comments: Eats mainly insects and amphibians, also reptiles and small rodents; usually feeds on dry or moist ground near cattle or horses, away from water (Terres 1980), sometimes near farm machinery.

The common name of the cattle egret comes from their familiar habit of foraging in pasturelands in association with livestock animals whose movements and grazing activities flush out insect and other potential prey items. Cattle egrets will also follow tractors in order to feed on the organisms that are scared up (Scott 1987, Kaufman 1996). Crickets, grasshoppers, beetles, moths, flies, and other small invertebrates and vertebrates make up the bulk of the diet. Bubulcus ibis is an opportunistic forager; it will eat parasites off of the bodies of the livestock with which they coexist and can also consume relatively large prey items like crayfish, fish, frogs, small snakes, and even bird eggs and nestling birds. In urbanized settings cattle egrets will scavenge trash heaps for edible material (Kaufman, 1996).

In the African portion of their native range, cattle egrets co-occur with elephants, rhinoceros, hippopotamus, and other large herbivores, and across much of their non-native range they associate primarily with cattle (Telfair 1994, Ivory 2000).Invasion History: Cattle egrets are notable among exotic species in that they are one of the very few cases in which initial expansion into historically non-native areas appears to be a largely natural occurrence unassisted by humans (Weber, 1972). The species is highly migratory and is capable of dispersing in seemingly random directions across thousands of kilometers in a few days (Kaufman 1996, CAST 2002).Although the initial entry of Bubulcus ibis into New World appears to have not relied on the helping hand of man, current range expansion within the U.S. is related to extensive landscape conversion to pasturelands (Telfair 1994).The first appearance of B. ibis in the New World dates to the late 1870s and 1880s from Suriname in northeastern South America. By 1917, they had appeared in Colombia, although they were not reported from Panama until 1954. B. ibis apparently arrived in Florida in the 1940s and had begun establishing breeding populations in the state in the 1950s (Wetmore 1965, Hilty and Brown 1986). The animal is now abundant year-round throughout Florida. Potential to Compete With Natives: Bubulcus ibis is highly adaptable and capable of living in a number of human-altered agricultural and urbanized environments. Although the potential exists for them to out-compete co-occurring native species for nesting areas and food resources, published findings suggest there has been little impact of B. ibis on native species in the U.S. (Weber 1972, Kauffman 1996). Cattle egrets often occur as part of mixed-species nesting assemblages, and Maxwell and Kale (1977) note that peak nesting in cattle egrets occurs after that of most native herons. Dietary niche overlap is probably also minimal as the diet of cattle egrets consists primarily of insects and terrestrial invertebrates whereas other herons consume mostly primarily fish and aquatic invertebrates (Weber 1972). Possible Economic Consequences of Invasion: The negetive economic impacts of cattle egrets in the IRL region and in Florida in general is likely to be minimal.

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: > 300

>1,000,000 individuals

Comments: Most of coastal U.S. breeding population is on the Florida coast (250,000 birds) and Gulf Coast (170,000); 20,000 breeders on the Atlantic coast north of Florida. Preceding population figures do not include birds breeding in inland sites (e.g., 242,000 in Texas in 1979). Breeding populations often vary greatly in successive years.

Cattle egrets are abundant throughout Florida. Bryan et al (2003) reports that Bubulcus ibis was the most common nesting species in nesting bird colony surveys conducted in the Upper St. Johns River basin in 1993-1995 and 1998-2000. Similarly, Dugger et al (2005) confirmed that that B. ibis was the most abundant waterbird utilizing the channelized Kissimmee River in the wet season during surveys conducted between 1996 and 1998. This information confirms the ability of B. ibis to effectively utilize urbanized or otherwise altered habitats.

Often flies in large flocks in morning and evening.

"The Cattle Egret is less dependent on the neighbourhood of water than are most of its family. It is met with gregariously on grass- and pasture-land both on the margins of tanks and jheels as well as further inland. The birds are in constant attendance on grazing cattle, stalking alongside the animals, running in and out between their legs, or riding on their backs for a change. They keep an unceasing look-out for the grasshoppers and other insects disturbed in the animals' progress through the grass, darting out their long flexible necks and pointed bills and snapping them up as soon as they show any movement. They also pick off blood-sucking flies, ticks and other parasitic insects from the backs and bellies of the oxen and buffaloes, jumping up for them as they scurry alongside or alighting complacently on the animals' heads and backs to reach the less accessible parts. Their staple food, unlike that of their marsh-haunting cousins, is insects, but they do not despise frogs and lizards whenever available. Flies—both the House-Fly and the Blue-bottle-—are greatly relished. The birds are as a rule tame, running or stalking about fearlessly amongst the cattle within a few feet of the observer, and completely engrossed in the search for food. Cattle Egrets have regular roosts in favourite trees to which they resort every evening, flying more or less in a disorderly rabble, with neck folded back, head hunched in between the shoulders, legs tucked under the tail and projecting behind like a rudder."

Range lifespan
Status: wild: 23 (high) years.

Average lifespan
Status: wild: 204 months.

Maximum longevity: 23 years (wild) Observations: In Hawaii, reported to breed twice a year and year round (http://bna.birds.cornell.edu/).

"The season, depending on the monsoons, is mainly June to August in N. India ; November /December in the south. The birds breed in colonies usually in company with PaddyBirds and sometimes also with Darters, cormorants and herons. The nest is of the usual crow pattern—an untidy structure of twigs. It is built in trees not necessarily near water and often in the midst of a noisy bazaar in a town or village. Three to 5 eggs form the normal clutch. They are a pale skim-milk blue in colour."

The cattle egret is seasonally monogamous. It pair-bonds, but at the start of the breeding season there can be a temporary group of 1 male and 2 females. Breeding starts when small groups of males establish territories. Soon after this, aggression increases, and they begin to perform various elaborate courtship displays, attracting groups of females. Immediately before pairing, a female will attempt to subdue the displaying male by landing on his back. Eventually, the male will allow one female to remain in his territory, and within a few hours, the pair-bond is secure. The female then follows the male to another site where the nest will be built. Copulation usually also takes place at this second site. There is little display involved with copulation. Some rapes and rape attempts have been documented. (Telfair, 1994)

Cattle egrets nest is large colonies with other wading birds. Pairs sometimes reuse old nests, or build new ones with live or dead vegetation. They will build in any place that can support a nest. Both sexes participate in nest-building: the female usually builds with materials brought by the male. They often steal sticks and other materials from neighbors' unattended nests. Material is continuously added to the bulky nests during incubation and after hatching. Throughout mating, nesting, and incubation, a Greeting Ceremony is given whenever one mate returns to the nest to join the other. The Greeting Ceremony involves erection of the back plumes, and flattening of the crest feathers. Eggs are laid every 2 days, and the female does not become attentive to the nest until the last egg is laid. The eggs are light sky blue, turning lighter as time passes. Clutch size is usually 3-4 eggs, although extremes of 1 and 9 have been recorded. Incubation is carried out by both sexes, and lasts 24 days. During the first week, nestlings are easily overheated, and so the parents shade them from the sun beneath their wings. Both parents brood constantly for the first 10 days. The parents may accept chicks from other broods only if they are less than 14 days old. Begging for food becomes very aggressive in days 4-8, and the nestlings are very competative with one another. Siblicide is uncommon, though sibling aggression is strong. Most of the chicks' growth is completed in the nest, but by 14-21 days, the chicks are capable of leaving the nest and climbing in vegetation, and are thus referred to as 'branchers.' At this stage, they remain nearby and continue to beg for food. At 45 days, they are independent, at 50 days they can make short flights, and at around 60 days, they fly to foraging areas. (Telfair, 1994;   http://www.coos.or.us/~aigrette/ce.htm)

Average time to hatching: 22 days.

Average eggs per season: 3.

Clutch size is 2-6 (commonly 3-4). Incubation, by both sexes, lasts 21-24 days. Young can fly short distances at 40 days, reasonably well at 50 days. May breed at 1 year. Usually nests in colonies.

Cattle egret breeding season in central Florida extends from mid April through July (Weber 1972). Individuals enter the breeding population at 2-3 years of age (Kaufman 1996).Cattle egrets are colonial breeders that are often found alongside other species of herons and egrets in mixed-colony shoreline breeding assemblages. Males establish breeding territories and courtship involves elaborate male displays. Once pairs have been established females construct nests utilizing material provided mainly by the males. Nest building and breeding is usually completed in three days, after which the birds begin to lose their breeding colors (Weber 1972, Kaufman 1996).There is a degree of promiscuity in the species, with males frequently mating with more than one female during the breeding season (McKilligan 1990).

Mean clutch size of Bubulcus ibis in Florida is approximately 3-4 eggs per nest, although clutch sizes ranging from 1-9 eggs have been recorded (Weber 1972, Kaufman 1996). One egg with a length of 4-5 cm is laid every other day during nesting, and the eggs hatch sequentially, approximately 24 days after they are laid. Survival retes of the earlier hatchlings is better than that of the later hatchlings, and is related to food availability (Weber 1972, 1975). Fledglings begin to fly 25-30 days after hatching, and they become independent around 45 days post-hatch (Kaufman, 1996).

The following is a representative barcode sequence, the centroid of all available sequences for this species.

There are 10 barcode sequences available from BOLD and GenBank.  Below is a sequence of the barcode region Cytochrome oxidase subunit 1 (COI or COX1) from a member of the species.  See the BOLD taxonomy browser for more complete information about this specimen and other sequences.

Download FASTA File

Barcode of Life Data Systems (BOLDS) Stats
Public Records: 16
Specimens with Barcodes: 26
Species With Barcodes: 1

Canada

Rounded National Status Rank: N1B - Critically Imperiled

United States

Rounded National Status Rank: N5B,N5N : N5B: Secure - Breeding, N5N: Secure - Nonbreeding

Year Assessed

Assessor/s

Reviewer/s

Contributor/s

Justification

History

• 2008
  Least Concern
• 2004
  Least Concern

The cattle egret is the most plentiful ardeid in many areas of the U.S. Its range continues to expand as a result of widespread landscape conversion to pasturelands, where these birds forage with cattle. (Telfair, 1994)

US Migratory Bird Act: protected

US Federal List: no special status

CITES: no special status

State of Michigan List: no special status

IUCN Red List of Threatened Species: least concern

Resident breeder, regular passage visitor and winter visitor.

Rounded Global Status Rank: G5 - Secure

Population

Global Long Term Trend: Increase of >25%

Comments: U.S. population increased greatly between the 1950s and early 1970s (Bock and Lepthien 1976). Breeding Bird Survey data indicate a significant population increase in North America between 1966 and 1989 (Droege and Sauer 1990). See Spendelow and Patton (1988) for further details.

Major Threats

Cattle egrets may transmit parasites and other disease organisms to livestock and people, but this is very speculative. Some heronries are considered nuisances when near structures used by humans due to noise, odor, concern over health hazards, and potential danger to aircraft. (Telfair)

Some ranchers rely on cattle egrets for fly control more than they do pesticides.