Animal Diversity Web

Ge­o­graphic Range

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

Habi­tat

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

Phys­i­cal De­scrip­tion

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)

• Other Physical Features
• endothermic
• bilateral symmetry

• Average mass

  220 g

  7.75 oz

  AnAge

Re­pro­duc­tion

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)

• Key Reproductive Features
• iteroparous
• gonochoric/gonochoristic/dioecious (sexes separate)
• sexual
• oviparous

• Average eggs per season

  3

  AnAge

• Average time to hatching

  22 days

  AnAge

Lifes­pan/Longevity

• Range lifespan
  Status: wild

  23 (high) years

• Average lifespan
  Status: wild

  204 months

  Bird Banding Laboratory

Be­hav­ior

The cat­tle egret is very gre­gar­i­ous and can be eas­ily iden­ti­fied by its ten­dency to as­so­ci­ate closely with graz­ing an­i­mals. It tends to roost in large colonies, usu­ally with other species of colo­nial wa­ter­birds. It is strongly mi­gra­tory. How­ever, dis­tin­guish­ing be­tween mi­gra­tion and dis­per­sal in cat­tle egrets is very dif­fi­cult be­cause they have a ten­dency to wan­der ex­ten­sively. It often flocks with other ardeids dur­ing mi­gra­tion. They also fly in flocks to and from feed­ing, breed­ing, and roost­ing sites. In flight, it tucks its neck in close to its body, or holds it in an S-shape. Even at rest, the neck is rarely ex­tended. It walks in a sway­ing man­ner, much like a goose. Some in­di­vid­u­als may 'leapfrog' over one an­other while mov­ing across the feed­ing area. It is ca­pa­ble of eva­sive manu­vers and usu­ally doesn't swim un­less it is pur­sued. The cat­tle egret is usu­ally silent when it is away from its roost, and it has no spe­cial flock­ing or flight calls. It gives most calls at the breed­ing colony, and its voice is a sim­ple, husky, quiet 'rick-rack.' In­di­vid­u­als de­fend their perch sites. Out­side of the breed­ing sea­son, there is lit­tle ag­gres­sive be­hav­ior, but dur­ing the breed­ing sea­son, en­coun­ters are in­tense. The erec­tion of the crest is in­dica­tive of the bird's level of an­tag­o­nism. At the colony site, the male may de­fend one or two ter­ri­to­ries. After pairs are formed, to­gether both mem­bers de­fend the nest­ing ter­ri­tory. There is no ter­ri­to­ri­al­ism at the feed­ing sites, as they feed al­most ex­clu­sively in flocks. (Telfair, 1994; http://​mbr.​nbs.​gov/​id/​htmid/​h2001id.​html)

• Key Behaviors
• flies
• motile

Com­mu­ni­ca­tion and Per­cep­tion

• Perception Channels
• visual
• tactile
• acoustic
• chemical

Food Habits

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)

Eco­nomic Im­por­tance for Hu­mans: Pos­i­tive

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

Eco­nomic Im­por­tance for Hu­mans: Neg­a­tive

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)

Con­ser­va­tion Sta­tus

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)

• IUCN Red List

  Least Concern
  More information

• IUCN Red List

  Least Concern
  More information

• US Migratory Bird Act

  Protected

• US Federal List

  No special status

• CITES

  No special status

• State of Michigan List

  No special status

Other Com­ments

The cat­tle egret now out­num­bers the com­bined pop­u­la­tions of all other egrets and herons found in North Amer­ica. No other egret spends as lit­tle time near water than does the cat­tle egret. ( http://​www.​coos.​or.​us/​~ai­grette/ce.​htm)

It is some­times called by names of the an­i­mal it as­so­ci­ates with, such as Ele­phant Bird, Rhi­noc­eros Egret, or Hip­popo­to­mus Egret.

Three sub­species are rec­og­nized: B. i. ibis, B. i. sey­chel­larum, and B. i. coro­manda. (Telfair, 1994)

Con­trib­u­tors

Ali­cia Ivory (au­thor), Uni­ver­sity of Michi­gan-Ann Arbor.

Ref­er­ences

Han­cock, J. and H. El­liot. The Herons of the World. Harper and Row Pub­lish­ing, New York, 1978.

Telfair, R.C. II. 1994. Cat­tle Egret (Bubul­cus ibis). In The Birds of North Amer­ica, No. 113 (A. Poole and F. Gill, Eds.). Philadel­phia: The Acad­emy of Nat­ural Sci­ences; Wash­ing­ton, D.C.: The Amer­i­can Or­nithol­o­gists' Union.

http://​www.​coos.​or.​us/​~ai­grette/ce.​htm

http://​www.​mbr.​nbs.​gov/​id/​htmid/​h2001id.​html