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{{short description|Bird in the ibis family}}
{{about|the American white ibis|the Australian bird|Australian white ibis}}
{{Speciesbox
| status = LC
| status_system = IUCN3.1
| status_ref = <ref name="IUCN">{{cite iucn |author=BirdLife International |date=2021 |title=''Eudocimus albus'' |page=e.T22697411A188454802 |doi=10.2305/IUCN.UK.2021-3.RLTS.T22697411A188454802.en |access-date=4 January 2023}}</ref>
| image = American_White_IbisII.jpg
| image_caption = An American white ibis wading in the [[Tampa Bay]] area of [[Florida]]
| taxon = Eudocimus albus
| authority = ([[Carl Linnaeus|Linnaeus]], [[10th edition of Systema Naturae|1758]])
| range_map = Eudocimus albus map 2.svg
| range_map_caption = {{leftlegend|#8d5fd3|Year-round |outline=gray}}{{leftlegend|#87aade|Non-breeding |outline=gray}}{{leftlegend|#ffe680|Passage|outline=gray}}
| synonyms = *''Scolopax alba'' {{small|Linnaeus, 1758}}
*''Scolopax fusca'' {{small|Linnaeus, 1758}}
*''Tantalus albus'' {{small|Linnaeus, 1766}}
*''Tantalus fuscus'' {{small|Linnaeus, 1766}}
}}
The '''American white ibis''' ('''''Eudocimus albus''''') is a species of [[bird]] in the [[ibis]] family, [[Threskiornithidae]]. It is found from the southern half of the [[East Coast of the United States|US East Coast]] ([[Virginia]], [[Carolinas|the Carolinas]] and [[Georgia (U.S. state)|Georgia]]), along the [[Gulf Coast of the United States|Gulf Coast]] states ([[Florida]], [[Alabama]], [[Mississippi]], [[Louisiana]] and [[Texas]]) and south through most of the Caribbean coastal regions of Central America.<ref name="White Ibis, Identification, All About Birds">{{cite web|url=http://www.allaboutbirds.org/guide/White_Ibis/id |title=White Ibis, Identification |author=Cornell Lab of Ornithology |work=All About Birds |publisher=Cornell University |___location=Ithaca, New York |access-date=9 January 2012}}</ref> This particular ibis species is a medium-sized [[Wader (American)|wading bird]], possessing an overall white [[plumage]] with black wing-tips (usually only visible in flight), and having the typical downward-curving [[Beak|bill]] of the ibises, though of a bright red-orange color, the same hue as its long legs. Males are larger and have longer bills than females. The [[breeding season|breeding]] range runs along the Gulf and [[East Coast of the United States|Atlantic Coast]], and the coasts of Mexico and Central America. Outside the breeding period, the range extends further inland in North America and also includes the [[Caribbean]]. It is also found along the northwestern South American coastline in Colombia and Venezuela. Populations in central Venezuela overlap and interbreed with the [[scarlet ibis]]. The two have been classified by some authorities as a single species.
Their diet consists primarily of small aquatic prey, such as insects and small fishes. [[Crayfish]] are its preferred food in most regions, but it can adjust its diet according to the habitat and prey abundance. Its main [[foraging]] behavior is probing with its beak at the bottom of shallow water to feel for and capture its prey. It does not see the prey.
During the breeding season, the American white ibis gathers in huge [[Bird colony|colonies]] near water. Pairs are predominantly [[Monogamy in animals|monogamous]] and both parents care for the young, although males tend to engage in [[Promiscuity#Extra-pair copulation in non-humans|extra-pair copulation]] with other females to increase their [[reproductive success]]. Males have also been found to [[Kleptoparasitism|pirate]] food from unmated females and juveniles during the breeding season.
Human pollution has affected the behavior of the American white ibis via an increase in the concentrations of [[methylmercury]], which is released into the environment from untreated waste. Exposure to methylmercury alters the hormone levels of American white ibis, affecting their mating and [[Nesting instinct|nesting]] behavior and leading to lower reproduction rates.
==Taxonomy==
The American white ibis was one of the many [[Aves in the 10th edition of Systema Naturae|bird species originally described]] by [[Carl Linnaeus]] in the 1758 [[10th edition of Systema Naturae|10th edition]] of his ''[[Systema Naturae]]'', where it was given the [[Binomial nomenclature|binomial name]] of ''Scolopax albus''.<ref>{{cite book |last=Linnaeus |first=Carl |author-link=Carl Linnaeus |title=Systema Naturae per Regna Tria Naturae, Secundum Classes, Ordines, Genera, Species, cum Characteribus, Differentiis, Synonymis, Locis. Tomus I. Editio decima, reformata |publisher=Laurentius Salvius |___location=Holmiae (Stockholm, Sweden) |language=la |year=1758 |page=145 |url=https://archive.org/stream/carolilinnaeisy00gesegoog#page/n154/mode/1up}}</ref> The [[specific name (zoology)|species name]] is the [[Latin]] adjective {{lang|la|[[:wikt:albus|albus]]}} "white".<ref>{{cite book |last=Simpson |first=D.P. |title=Cassell's Latin Dictionary |publisher=Cassell Ltd. |year=1979 |edition=5th |___location=London |page=33 |isbn=978-0-304-52257-6}}</ref> Alternative common names that have been used include Spanish curlew and white curlew.<ref name="Nellis01"/> English naturalist [[Mark Catesby]] mistook immature birds for a separate species, which he called the brown curlew.<ref>{{cite book |last1=Feduccia |first1=Alan |last2=Peterson |first2=Russell W. |title=Catesby's Birds of Colonial America |publisher=UNC Press Books |year=1999 |pages=28–29 |isbn=978-0-8078-4816-6 |url=https://books.google.com/books?id=hVVNvPMBGEkC&q=%22White+Ibis%22+American+indian&pg=PA28}}</ref> Local [[Louisiana Creole French|creole]] names in [[Louisiana]] include ''bec croche'' and ''petit flaman''.<ref name=JAA>{{cite book |author-link=John James Audubon |last=Audubon |first=John James |title=Ornithological biography, or, An account of the Habits of the Birds of the United States of America |publisher=A. Black |___location=Edinburgh, Scotland |year=1835 |pages=176–180 |url=https://books.google.com/books?id=c1dHAAAAYAAJ&q=%22White+Ibis%22+American+indian&pg=PA176}}</ref>
[[Johann Georg Wagler]] gave the species its current binomial name in 1832 when he erected the new genus ''[[Eudocimus]]'', whose only other species is the [[scarlet ibis]] (''E. ruber''). There has long been debate on whether the two should be considered [[subspecies]] or closely related species,<ref name=Hancock10>{{cite book |last1=Hancock |first1=James |last2=Kushlan |first2=James A. |title=Storks, Ibises and Spoonbills of the World |chapter=American White Ibis |publisher=A&C Black |___location=London |year=2010 |orig-year=1992 |isbn=978-1-4081-3500-6}}</ref> and the [[American Ornithologists' Union]] considers the two to be a [[superspecies]] as they are [[Parapatric speciation|parapatric]].<ref name=ramo/> The lack of observed [[Hybrid (biology)|hybrids]] was a large factor in the view that the species were separate.<ref name=Hancock10/>
However, in a field study published in 1987, researchers Cristina Ramo and Benjamin Busto found evidence of interbreeding in a population where the ranges of the scarlet and white ibises overlap along the coast and in the [[Llanos]] region of Colombia and Venezuela. They observed individuals of the two species mating and pairing, as well as hybrid ibises with pale orange plumage, or white plumage with occasional orange feathers; their proposal that these birds be classified as a single species,<ref name=ramo>{{Cite journal | last1 = Ramo | first1 = Cristina| last2 = Busto | first2 = Benjamin | title = Hybridization Between the Scarlet Ibis (''Eudocimus ruber'') and the White Ibis (''Eudocimus albus'') in Venezuela | journal = Colonial Waterbirds | volume = 10 | issue = 1 | pages = 111–14 | doi = 10.2307/1521240 | year = 1987 | jstor = 1521240}}</ref><!-- cites previous three sentences --> has been followed by least one [[field guide]].<ref name="Nellis01">{{cite book |last=Nellis |first=David W. |title=Common Coastal Birds of Florida & the Caribbean |publisher=Pineapple Press |___location=Sarasota, Florida |year=2001 |pages=151–55 |isbn=978-1-56164-191-8 |url=https://books.google.com/books?id=-REZ4R8wBg4C&q=American+White+Ibis&pg=PA155}}</ref> Hybrid ibises have also been recorded in Florida, where the scarlet ibis has been [[Introduced species|introduced]] into wild populations of American white ibis. Birds of intermediate to red plumage have persisted for generations.<ref name=Hancock10/>
Ornithologists James Hancock and Jim Kushlan also consider the two to be a single species, with the differences in plumage, size, skin coloration and degree of bill darkening during breeding season forming the diagnostic characters. They have proposed the populations recontacted in northwestern South America after a period of separation, and that the color difference is likely due to the presence of an [[enzyme]] that allows uptake of [[pigment]] in the diet. They have questioned whether white-plumaged birds of South America are in fact part of the ''ruber'' rather than the ''albus'' [[taxon]], and acknowledge that more investigation is needed to determine this.<ref name=Hancock10/>
==Description==
[[File:Eudocimus albus -Huntington Beach State Park, South Carolina, USA -flying-8.jpg|thumb| in [[Huntington Beach State Park]], South Carolina, United States]]
[[File:White ibis (Eudocimus albus ramobustorum) in flight.jpg|thumb|''E. a. ramobustorum'' off [[Boca Chica, Chiriquí]], [[Panama]]]]
The white plumage and pink facial skin of adult American white ibises are distinctive.<ref>{{cite book |title=Field Guide to the Birds of North America |editor-first=Shirley L. |editor-last=Scott |page=56 |year=1983 |publisher=National Geographic Society |___location= Washington D.C.}}</ref> Adults have black wingtips that are usually only visible in flight.<ref name="White Ibis - Birds of North America Online" /> In non-breeding condition the long downcurved bill and long legs are bright red-orange.<ref name="White Ibis | National Audubon Society Birds">{{cite web|url=http://birds.audubon.org/species/whiibi |title=White Ibis |work=National Audubon Society Birds website |publisher=National Audubon Society, Inc. |access-date=16 May 2011 |url-status=dead |archive-url=https://web.archive.org/web/20111123210016/http://birds.audubon.org/species/whiibi |archive-date=23 November 2011 }}</ref> During the first ten days of the breeding season, the skin darkens to a deep pink on the bill and an almost purple-tinted red on the legs. It then fades to a paler pink, and the tip of the bill becomes blackish.<ref>{{Cite journal | last1 = Heath | first1 = J. A. | last2 = Frederick | first2 = P. C. | doi = 10.1111/j.1557-9263.2006.00034.x | title = White Ibis Integument Color During the Breeding Season | journal = Journal of Field Ornithology | volume = 77 | issue = 2 | pages = 141–150 | year = 2006 | url = http://www.wec.ufl.edu/faculty/frederickp/publications/heath%20Frederick%2006%20White%20Ibis%20integument%20color%20during%20the%20breeding%20season.pdf}}</ref> It is difficult to determine the sex of an adult American white ibis from its external appearance, since the sexes have similar plumage.<ref name="Herring, G., Gawlik, D. E. & Beerens, J. M. 2008. Sex determination for the Great Egret and White Ibis.">{{cite journal |last1=Herring |first1=Garth |last2=Gawlik |first2=Dale E. |last3=Beerens |first3=James M. |title=Sex Determination for the Great Egret and White Ibis |journal=Waterbirds |volume=31 |issue=2 |year=2008 |pages=298–303 |issn=1524-4695 |doi=10.1675/1524-4695(2008)31[298:SDFTGE]2.0.CO;2 |s2cid=37789406 |url=http://www.science.fau.edu/biology/gawliklab/papers/HerringGetal2008.pdf |access-date=2014-04-24 |archive-url=https://web.archive.org/web/20140424074732/http://www.science.fau.edu/biology/gawliklab/papers/HerringGetal2008.pdf |archive-date=2014-04-24 |url-status=dead }}</ref> However, there is [[sexual dimorphism]] in size and proportion as males are significantly larger and heavier than females and have longer and stouter bills.<ref name="Kushlan, James A., 1975. Sexual Dimorphism in the White Ibis"/> This species is moderately large for an ibis but is relatively short legged, compact and bulky for a large wader. A study of the American white ibis in southern Florida yielded weight ranges of {{convert|872.9|to|1261|g|lb|abbr=on}} for males and {{convert|592.7|to|861.3|g|lb|abbr=on}} for females, with average weights of {{convert|1036.4|g|lb|abbr=on}} for males and {{convert|764.5|g|lb|abbr=on}} for females.<ref name="Kushlan, James A., 1975. Sexual Dimorphism in the White Ibis">{{Cite journal | last1 = Kushlan | first1 = J. A. | title = Sexual Dimorphism in the White Ibis | journal = The Wilson Bulletin | volume = 89 | issue = 1 | pages = 92–98 | url = http://sora.unm.edu/sites/default/files/journals/wilson/v089n01/p0092-p0098.pdf| year = 1977 | jstor = 4160873}}</ref><ref name="CRC">{{cite book |title=CRC Handbook of Avian Body Masses |editor-last=Dunning Jr. |editor-first=John B. |year=1992 |publisher=CRC Press |___location=Boca Raton, Florida |isbn=978-0-8493-4258-5}}</ref> The length of adult female and male birds ranges from {{convert|53|to|70|cm|in|abbr=on}} with a {{convert|90|to|105|cm|in|abbr=on}} wingspan.<ref name="White Ibis, Life History, All About Birds">{{cite web |url=http://www.allaboutbirds.org/guide/White_Ibis/lifehistory |title=White Ibis, Life History |author=Cornell Lab of Ornithology |work=All About Birds |publisher=Cornell University |___location=Ithaca, New York|access-date=9 January 2012}}</ref><ref name="White Ibis">{{cite web |url=http://www.sms.si.edu/irlspec/eudoc_albus.htm |title=White Ibis |work=Smithsonian Marine Station at Fort Pierce |___location=Fort Pierce, Florida |last=Hill |first=K. |year=2001 |access-date=16 May 2011}}</ref> Among standard measurements, American white ibis measure {{convert|20.5|-|31|cm|in|abbr=on}} along each wing, have a tail measurement of {{convert|9.3|-|12.2|cm|in|abbr=on}}, a [[Tarsus (skeleton)|tarsus]] of {{convert|6.75|-|11.3|cm|in|abbr=on}} and a [[Culmen (bird)|culmen]] of {{convert|11|-|16.9|cm|in|abbr=on}}.<ref name=Hancock10/>
The newly hatched American white ibis is covered with violet [[down feather]]s, deepening to dark brown or black on the head and wings. The chest is often bare and there can be a white tuft on the head. The [[Iris (anatomy)|irises]] are brown. The exposed skin is pinkish initially, apart from the tip of the bill which is dark gray, but turns gray within a few days of hatching.<ref name=Hancock10/><!-- cites previous four sentences --> The bill is short and straight at birth and has an [[egg tooth]] which falls off between days five and nine,<ref name=desanto90>{{cite journal |title=Plumage and Behavioral Development of Nestling White Ibises |last1=De Santo |first1=Toni L. |last2=McDowell |first2=Susan G. |last3=Bildstein |first3=Keith L. |journal=The Wilson Bulletin |volume=102 |issue=2 |pages=226–38 |year=1990 |jstor=4162861 |url=https://sora.unm.edu/sites/default/files/journals/wilson/v102n02/p0226-p0238.pdf }}</ref> and develops three black rings from around day six, before turning gray by around six weeks of age. The gray to sandy gray brown juvenile plumage appears between weeks two and six, and face and bill become pink a few weeks later, while the legs remain gray. The irises have turned slate-gray by this stage.<ref name=Hancock10/><!-- cites previous three sentences --> Once [[fledge]]d, the juvenile American white ibis has largely brown plumage and only the rump, underwing and underparts are white.<ref name="White Ibis - Birds of North America Online" /> The legs become light orange. As it matures, white feathers begin appearing on the back and it undergoes a gradual [[Moulting#Birds|molt]] to obtain the white adult plumage.<ref name="White Ibis - Birds of North America Online" /> This is mostly complete by the end of the second year, although some brown feathers persist on the head and neck until the end of the third year. Juvenile birds take around two years to reach adult size and weight.<ref name=Hancock10/><!-- cites previous two sentences -->
Like other species of ibis, the American white ibis flies with neck and legs outstretched, often in long loose lines or [[V formation]]s—a 1986 field study in North Carolina noted over 80% of adult ibis doing so, while juveniles rapidly took up the practice over the course of the summer. The resulting improvement in [[aerodynamics]] may lower energy expenditure.<ref>{{cite journal |title=Development of Formation Flying in Juvenile White Ibises (''Eudocimus albus'') |last1=Petit |first1=Daniel R. |last2=Bildstein |first2=Keith L. |journal=The Auk |volume=103 |issue=1 |year=1986 |pages=244–246 |jstor=4086997}}</ref><!-- cites previous two sentences--> These lines fly in an undulating pattern as they alternately flap and glide. Soaring in a circular pattern is also seen.<ref name=peterson02/><!-- cites previous two sentences--> Heights of {{convert|500|to|1000|m|ft|abbr=on|sigfig=2}} may be reached as birds glide over flights of {{convert|20|km|mi|abbr=on|sigfig=2}} or more. More commonly, birds fly between {{convert|60|and|100|m|ft|abbr=on}} above the ground, gliding or flapping at a rate of around 3.3 wingbeats a second.<ref name=bnabehaviour>{{cite web |url=https://bna.birds.cornell.edu/bna/species/009/articles/behavior |last1=Heath |first1=Julie A. |last2=Frederick |first2=Peter C. |last3=Kushlan |first3=James A. |last4=Bildstein |first4=Keith L. |title=White Ibis: Behavior |work=Birds of North America Online |publisher=Cornell University |date=10 February 2009 |access-date=15 January 2012}}</ref><!-- cites previous two sentences -->
The main [[bird vocalization|call]] of the American white ibis is a honking sound, transcribed as ''urnk, urnk'',<ref name="White Ibis, Sounds, All About Birds">{{cite web |url=http://www.allaboutbirds.org/guide/White_Ibis/sounds/ac |title=White Ibis, Sounds |author=Cornell Lab of Ornithology |work=All About Birds |publisher=Cornell University |___location=Ithaca, New York |access-date=13 January 2012}}</ref> or ''hunk, hunk''.<ref name=Hancock10/> The call is used in flight, courtship or when disturbed. Birds also utter a muted ''huu-huu-huu'' call while foraging, and make a squealing call in courtship. Young in the nest give a high-pitched ''zziu'' as a begging call.<ref name=Hancock10/><!-- cites previous three sentences -->
===Similar species===
Immature American white and scarlet ibises are very difficult to tell apart, although scarlet ibises tend to have darker legs and bare skin around the face.<ref>{{cite journal |last=Schell |first=Edward H. |year=1968 |title=A First Ohio Record of the White Ibis ''Eudocimus albus'' |journal=The Ohio Journal of Science |volume=68 |issue=1 |pages=17–18 |issn=0030-0950 |hdl=1811/5355/V68N01_017.pdf }}</ref> An immature American white ibis could be mistaken for an immature [[glossy ibis]], but the latter is wholly dark brown and lacks the white belly and rump. The adult is distinguishable from the [[wood stork]], which is much larger and its wings have more black on them.<ref name=peterson02>{{cite book |last1=Peterson |first1=Roger Tory |last2=Peterson |first2=Virginia Marie |title=Birds of Eastern and Central North America |publisher=Houghton Mifflin Harcourt |___location=Boston, Massachusetts |year=2002 |page=[https://archive.org/details/fieldguidetobird00pete_0/page/52 52] |isbn=978-0-395-74046-0 |url=https://archive.org/details/fieldguidetobird00pete_0|url-access=registration |quote=American White Ibis. }}</ref>
==Distribution and habitat==
[[File:American white ibis in a public park, Jacksonville, FL.pdf|thumbnail|right|An American white ibis at [[Riverside Park (Jacksonville)|Riverside Park]], [[Jacksonville]], Florida]]
[[File:Schneesichler (Eudocimus albus)-001.jpg|right|thumb|Adults in shallow water at [[Merritt Island National Wildlife Refuge]] near the Atlantic coast of Florida]]
The American white ibis is most common in Florida, where over 30,000 have been counted in a single [[Bird colony|breeding colony]]. It also occurs throughout the Caribbean, on both coasts of Mexico (from [[Baja California]] southwards) and Central America, and as far south as Colombia and Venezuela. The non-breeding range extends further inland, reaching north to [[Virginia]], and west to eastern [[Texas]]. [[File:American White Ibis.jpg|thumb|Adult American white ibis on pavement outside of Orlando, Florida]] The species is known to wander, and has been sighted, sometimes in small flocks, in states far out of its usual range.<ref name="Nellis01"/><ref name="White Ibis - Birds of North America Online">{{cite web |url=https://bna.birds.cornell.edu/bna/species/009/articles/introduction |last1=Kushlan |first1=James A. |last2=Bildstein |first2=Keith L. |title=White Ibis |work=Birds of North America Online |publisher=Cornell University |date=10 February 2009 |access-date=26 April 2011}}</ref>
In North America, breeding takes place along the [[East Coast of the United States|Atlantic coast]], from the southern New Jersey south to [[Florida]] and thence west along the [[Gulf Coast of the United States|Gulf Coast]].<ref name="White Ibis, Identification, All About Birds" /> [[Laguna Cuyutlán]] is an isolated and regionally important wetland in the state of [[Colima]] on México's west coast where a breeding colony has been recorded.<ref>{{cite journal |last1=Mellink |first1=Eric |last2=Riojas-Lopez |first2=Monica E. |year=2008 |title=Waterbirds (Other Than Laridae) Nesting in the Middle Section of Laguna Cuyutlan, Colima, Mexico |journal=Revista de Biología Tropical |volume=56 |issue=1 |pages=391–397 |pmid=18624252 |url=http://www.scielo.sa.cr/pdf/rbt/v56n1/art29v56n1.pdf |access-date=2011-12-17 |archive-url=https://web.archive.org/web/20120504165553/http://www.scielo.sa.cr/pdf/rbt/v56n1/art29v56n1.pdf |archive-date=2012-05-04 |url-status=dead }}</ref> American white ibises are not faithful to the sites where they breed,<ref>{{Cite journal | last1 = Frederick | first1 = P. C. | last2 = Bildstein | first2 = K. L. | last3 = Fleury | first3 = B. | last4 = Ogden | first4 = J. | title = Conservation of Large, Nomadic Populations of White Ibises (''Eudocimus albus'') in the United States | journal = Conservation Biology | volume = 10 | pages = 203–16 | year = 1996 | issue = 1 | doi = 10.1046/j.1523-1739.1996.10010203.x | bibcode = 1996ConBi..10..203F | url =http://www.wec.ufl.edu/faculty/frederickp/publications/Frederick%20et%20al%2096%20Conservation%20of%20nomadic%20populations%20of%20White%20Ibises.pdf}}</ref> and large breeding colonies composed of ten thousand birds or more can congregate and disband in one or two breeding seasons.<ref name=frederick97>{{cite journal |last1=Frederick |first1=Peter C. |last2=Ogden |first2=John C. |year=1997 |title=Philopatry and Nomadism: Contrasting Long-term Movement Behavior and Population Dynamics of White Ibises and Wood Storks |journal=Colonial Waterbirds |volume=20 |issue=2 |pages=316–323 |doi= 10.2307/1521699 |url=http://www.wec.ufl.edu/faculty/FrederickP/publications/Frederick%20Ogden%2097%20Philopatry%20and%20nomadism%20constrasting%20long%20term%20movement%20behavior.pdf |jstor=1521699 }}</ref> Breeding populations across its range have fluctuated greatly with wholesale movement between states.<ref name=bnademographics>{{cite web |url=https://bna.birds.cornell.edu/bna/species/009/articles/demography |last1=Heath |first1=Julie A. |last2=Frederick |first2=Peter C. |last3=Kushlan |first3=James A. |last4=Bildstein |first4=Keith L. |title=White Ibis: Demography and Populations |work=Birds of North America Online |publisher=Cornell University |date=10 February 2009 |access-date=14 January 2012}}</ref>
Until the 1940s, the species bred only in large numbers in Florida, mostly within the [[Everglades]].<ref name=frederick97/> Drought conditions elsewhere in the United States led to more than 400,000 American white ibis breeding there in the 1930s.<ref name=bnademographics/> In the 1950s and 1960s, large colonies appeared in [[Alabama]], Louisiana, and then [[North Carolina|North]] and [[South Carolina]] and the Gulf Coast of Florida, and finally Texas in the 1970s. Between the 1970s and early 1990s, breeding colonies declined and disappeared in South Carolina and Florida, and greatly increased in North Carolina<ref name=bnademographics/> and Louisiana.<ref name=frederick97/> Colonies last between one and seventeen years, their longevity related to size and quality of nearby [[wetland]]s. The longest-lasting are associated with wetlands over {{convert|800|km2|sqmi|abbr=on}} in size. Degradation of wetland or breeding sites are reasons for abandonment.<ref name=frederick97/> The population of American white ibises in a colony at Pumpkinseed Island in [[Georgetown County, South Carolina]], dropped from 10,000 to zero between 1989 and 1990 as [[Hurricane Hugo]] had inundated nearby freshwater foraging areas with salt water.<ref>{{cite journal |last1=Shepherd |first1=Philippa |last2=Crockett |first2=Tanja |last3=De Santo |first3=Toni L. |last4=Bildstein |first4=Keith L. |year=1991 |title=The Impact of Hurricane Hugo on the Breeding Ecology of Wading Birds at Pumpkinseed Island, Hobcaw Barony, South Carolina |journal=Colonial Waterbirds |volume=14 |issue=2 |pages=151–57 |jstor=1521504 |doi=10.2307/1521504}}</ref>
The American white ibis is found in a variety of [[habitat]]s, although shallow coastal marshes, wetlands and [[mangrove]] swamps are preferred.<ref name="Feeding Ecology and Prey Selection in the White Ibis">{{Cite journal | last1 = Kushlan | first1 = J. A. | title = Feeding Ecology and Prey Selection in the White Ibis | journal = The Condor | url=http://sora.unm.edu/node/103004| volume = 81 | issue = 4 | pages = 376–389 | doi = 10.2307/1366963 |jstor=1366963| year = 1979 | url-access = subscription }}</ref> It is also commonly found in muddy pools, on [[mudflat]]s and even wet lawns. Populations that are away from the coast and shoreline, particularly in southern Florida, often reside in other forms of wetlands such as marshes, ponds and flooded fields.<ref name="White Ibis, Identification, All About Birds" /><ref name="White Ibis - Birds of North America Online" /> In summer, these move to more coastal and [[Estuary|estuarine]] habitats as inland waterways become flooded with summer rains and the ibis find the water levels too deep to forage effectively.<ref name="Feeding Ecology and Prey Selection in the White Ibis"/>
===Fossil record===
Remains similar to the American white ibis have been found in [[Middle Pliocene]] deposits of the [[Bone Valley]] formation in central Florida, and [[Lower Pliocene]] deposits of the [[Yorktown Formation]] at Lee Creek in North Carolina.<ref name=olson>{{Cite journal | last1 = Olson | first1 = S. L. | title = The generic allocation of ''Ibis pagana'' Milne-Edwards, with a review of fossil ibises (Aves: Threskiornithidae) | journal = Journal of Vertebrate Paleontology | volume = 1 | issue = 2 | pages = 165–170 | year = 1981 | jstor = 4522847 | hdl= 10088/7085 | doi = 10.1080/02724634.1981.10011888| bibcode = 1981JVPal...1..165O | citeseerx = 10.1.1.510.7434 }}</ref> Two species, one living and one extinct, have been recovered from the [[Talara Tar Seeps]] in northern coastal Peru. ''[[Eudocimus peruvianus]]'' was described from a [[tarsometatarsus]] that differed slightly from ''E. albus'', whose remains were also found there. Remains of neither species are common in the beds. The tar seeps have been dated at 13,900 years old. The American white ibis is still found in Peru.<ref>{{cite book |last=Campbell |first=Kenneth E. |year=1979 |title=The Non-passerine Pleistocene Avifauna of the Talara Tar Seeps, Northwestern Peru |url=https://archive.org/stream/nonpasserineplei00camp#page/28/mode/2up/search/eudocimus |___location=Toronto, Ontario |publisher=Royal Ontario Museum |pages=28–32, 154 |isbn=978-0-88854-230-4}}</ref>
==Behavior==
[[File:American white Ibis birds in Dade City Florida.jpg|thumb|American white Ibis birds in [[Dade City, Florida|Dade City]], [[Florida]] ]]
A field study late in the Florida nesting season revealed that on an average day, adult American white ibis spent 10.25 hours looking for food, 0.75 hours flying, 13 hours resting, roosting, and attending to their nests.<ref name=" Population Energetics of the American White Ibis">{{Cite journal | last1 = Kushlan | first1 = J. A. | title = Population Energetics of the American White Ibis | journal = The Auk | volume = 94 | issue = 1 | pages = 114–122 | year = 1977 | jstor = 4084896| url=http://sora.unm.edu/node/22923}}</ref> Much of the time roosting is spent [[preening (bird)|preening]], biting and working their feathers with their long bills, as well as rubbing the [[uropygial gland|oil glands]] on the sides of their heads on back plumage. American white ibis generally only preen themselves, not engaging in [[Social grooming|allopreening]] unless part of courtship behavior. Bathing often takes place before preening; ibis squat in water {{convert|5|-|20|cm|in|abbr=on}} deep and flick water over themselves with each wing in succession. Hundreds of birds may bathe together around the time of courtship.<ref name=bnabehaviour/><!-- cites previous three sentences -->
The American white ibis is [[Territory (animal)|territorial]], defending the nesting and display sites against intruders. [[Agonistic behaviour|Agonistic]] or threat displays include lunging forward with the bill in a horizontal posture, and standing upright and snapping the bill opposite another bird engaging in the same display. Birds also lunge and bite, often holding onto an opponent's head or wings.<ref name=bnabehaviour/><!-- cites previous three sentences -->
===Breeding and lifespan===
[[File:White Ibis On Nest.jpg|thumb|right|A White Ibis on a nest in [[New Jersey]]]]
[[File:Ibis Tree.jpg|thumb|right|Birds roosting in a tree near [[St. Johns River]], Florida]]
The American white ibis pairs up in spring and breeds in huge [[Bird colony|colonies]], often with other waterbird species. Nesting begins as soon as suitable foraging and nesting habitat is available. The female selects the site, usually in the branches of a tree or shrub, which is often over water, and builds the nest, and males assist by bringing nest material.<ref name="White Ibis | National Audubon Society Birds" /> Anywhere from one to five [[bird egg|egg]]s are typically laid, with two or three being the most common. The eggs are matte pale blue-green in color with brown splotches, measure {{convert|5.8|x|3.9|cm|in|abbr=on}}, and weigh on average {{convert|50.8|g|oz|abbr=on}}.<ref name="Nellis01"/><!-- cites previous two sentences--> [[Clutch (eggs)|Clutch]] sizes are usually lower in coastal colonies as compared to inland colonies, although there are no statistically significant differences in the fledging rate of both colonies.<ref name=" Population Energetics of the American White Ibis"/> Throughout the mating and [[Avian incubation|incubation]] period, the male undergoes a period of [[starvation]] to stay close to the nest and aggressively defend his nest and mate from both predators and other ibises in preference to foraging for food.<ref name="Frederick, P. C. 1987. Responses of male White Ibises to their mate's extra-pair copulation behavior" /> In the 2006 breeding season, a non-breeding adult female was observed to be tending to multiple nests that belonged to other American white ibises—the first time the behavior has been documented for this species.<ref name="Multiple nest-tending behavior in an adult female White Ibis">{{cite journal |last1=Herring |first1=Garth |last2=Gawlik |first2=Dale E. |title=Multiple nest-tending behavior in an adult female White Ibis |journal=Waterbirds |volume=30 |issue=1 |year=2007 |pages=150–151 |issn=1524-4695 |doi=10.1675/1524-4695(2007)030[0150:MNBIAA]2.0.CO;2 |s2cid=86070552 |url=http://www.science.fau.edu/biology/gawliklab/papers/HerringGandDEGawlik2007c.pdf |access-date=2014-04-24 |archive-url=https://web.archive.org/web/20140424075329/http://www.science.fau.edu/biology/gawliklab/papers/HerringGandDEGawlik2007c.pdf |archive-date=2014-04-24 |url-status=dead }}</ref>
Although the American white ibis is predominantly [[Monogamy in animals|monogamous]] and both sexes provide parental care to their young, the male often flies off to engage in [[extra-pair copulation]] with other nesting females after mating with its primary female partner. These extra-pair copulations are usually done after the within-pair copulations,<ref name="Frederick, P.C. 1986. Extrapair Copulations in the Mating System">{{Cite journal | last1 = Frederick | first1 = P. C. | title = Extrapair Copulations in the Mating System of White Ibis (''Eudocimus albus'') | journal = Behaviour | volume = 100 | issue = 1 | pages = 170–201 | doi = 10.1163/156853987X00125 | year = 1987 | url = http://www.unc.edu/home/rhwiley/pdfs/FrederickExtrapairCops.pdf}}</ref> and make up about 45% of all total matings, although only about 15% of all extra-pair copulations are successful.<ref name="Frederick, P.C. 1986. Extrapair Copulations in the Mating System"/> By not restricting the number of females it copulates with, the male is able to increase its reproductive success considerably. Although females are receptive towards extra-pair copulations, male mate-guarding greatly reduces the rate of successful female involvement in attempted extra-pair copulations by other males.<ref name="Frederick, P. C. 1987. Responses of male White Ibises to their mate's extra-pair copulation behavior">{{Cite journal | last1 = Frederick | first1 = P. C. | title = Responses of Male White Ibises to Their Mate's Extra-Pair Copulations | journal = Behavioral Ecology and Sociobiology | volume = 21 | issue = 4 | pages = 223–228 | doi = 10.1007/BF00292503 | year = 1987 | bibcode = 1987BEcoS..21..223F | s2cid = 46708937 | url =http://www.wec.ufl.edu/faculty/frederickp/publications/Frederick%2087%20Responses%20of%20male%20White%20Ibises%20to%20their%20mate%27s.pdf}}</ref>
[[File:Juvenile American White Ibis.jpg|thumb|left|Juvenile in [[Everglades National Park]]. Some of its brown feathers have molted and have been replaced with white feathers.]]
The breeding success of the American white ibis is sensitive to the [[hydrology|hydrological]] conditions of the [[ecosystem]] such as rainfall and water levels. Low and decreasing water levels predict good prey accessibility. Water level reversals, where levels rise in the breeding season, disperse prey and impact on foraging success. Nest numbers and average clutch sizes are smaller in periods of reduced prey availability.<ref name="Sensitivity of nesting Great Egrets (Ardea alba) and White Ibises (Eudocimus albus) to reduced prey availability">{{cite journal |last1=Herring |first1=Garth |last2=Gawlik |first2=Dale E. |last3=Cook |first3=Mark. I. |last4=Beerens |first4=James M. |title=Sensitivity of nesting Great Egrets (Ardea alba) and White Ibises (Eudocimus albus) to reduced prey availability |journal=The Auk |volume=127 |issue=3 |year=2010 |pages=660–670 |issn=0004-8038 |doi=10.1525/auk.2010.09144 |s2cid=34344393 |url=http://www.science.fau.edu/biology/gawliklab/papers/HerringGetal2010.pdf |access-date=2014-04-24 |archive-url=https://web.archive.org/web/20140424075435/http://www.science.fau.edu/biology/gawliklab/papers/HerringGetal2010.pdf |archive-date=2014-04-24 |url-status=dead }}</ref><!-- cites two previous sentences --> The success rate of parents raising one or more young to 20 days of age ranges widely from 5 to 70% of nests, and varies greatly between nearby colonies.<ref name=bnademographics/> American white ibis parents have been known to supplement their chicks' diet with items such as cockroaches and rotting food from human garbage in poorer years, when fish and crayfish are more scarce.<ref>{{cite journal |last1=Dorn |first1=Nathan J. |last2=Cook |first2=Mark I. |last3=Herring |first3=Garth |last4=Boyle |first4=Robin A. |last5=Nelson |first5=Jennifer |last6=Gawlik |first6=Dale E. |title=Aquatic prey switching and urban foraging by the White Ibis Eudocimus albus are determined by wetland hydrological conditions |journal=Ibis |volume=153 |issue=2 |year=2011 |pages=323–335 |issn=0019-1019 |doi=10.1111/j.1474-919X.2011.01101.x |url=http://www.science.fau.edu/biology/gawliklab/papers/DornNJetal2011.pdf |access-date=2014-04-24 |archive-url=https://web.archive.org/web/20140424074728/http://www.science.fau.edu/biology/gawliklab/papers/DornNJetal2011.pdf |archive-date=2014-04-24 |url-status=dead }}</ref> Studies have also shown that years with higher nesting numbers had significantly faster spring drying rates of water bodies than years with low nesting numbers. This is because faster drying rates means that there are fewer fish and increased available area where crayfish can be hunted.<ref name="Nesting Success of Five Ciconiiform Species in Relation to Water Conditions in the Florida Everglades" /> This highlights the fact that American white ibises do not use probability of nesting failure as a key factor in determining nesting sites but instead, rely on other criteria such as prey availability and nest-site [[predation]] rates.<ref name="Chronic Tidally-Induced Nest Failure in a Colony of White Ibises" /> The draining of wetlands in south Florida has also impacted on species that forage in shallow water such as the American white ibis, and its increase in numbers is a key indicator of restoration of habitat within the Everglades.<ref>{{Cite journal | last1 = Frederick | first1 = Peter | last2 = Gawlik | first2 = Dale E. | last3 = Ogden | first3 = John C. | last4 = Cook | first4 = Mark I. | last5 = Lusk | first5 = Michael | title = The White Ibis and Wood Stork as Indicators for Restoration of the Everglades Ecosystem | doi = 10.1016/j.ecolind.2008.10.012 | journal = Ecological Indicators | volume = 9 | issue = 6 | pages = S83–S95 | year = 2009 | bibcode = 2009EcInd...9..S83F | url = http://www.wec.ufl.edu/faculty/frederickp/publications/Frederick%20et%20al%2009%20White%20Ibis%20and%20Wood%20Storks%20as%20indicators.pdf}}</ref>
The main cause of nest failure among the species is due to nest abandonment,<ref name="Nesting Success of Five Ciconiiform Species in Relation to Water Conditions in the Florida Everglades">{{Cite journal | last1 = Frederick | first1 = P. C. | last2 = Collopy | first2 = M. W. | title = Nesting Success of Five Ciconiiform Species in Relation to Water Conditions in the Florida Everglades | journal = The Auk | volume = 106 | issue = 4 | pages = 625–634 | year = 1989 | jstor = 4087667| url=http://sora.unm.edu/node/24760}}</ref> the leading cause of which is inundation from extremely high tides. Parents abandoned 61% of all nesting starts either during or immediately after extremely high tides. The eggs float out of the flooded nests, or get washed out into the sea by wave action. Incubating parents usually abandon the nest when the water or tidal levels reaches {{convert|3|to|8|cm|in|abbr=on}} above the bottom of the nest cup. Nevertheless, there have been instances where the parents have been observed to transport their eggs to another nest in an attempt to salvage some eggs. However, despite the fact that some nesting sites face high chance of tidal damage every breeding season, American white ibises still continue to nest in these areas because of other favorable conditions such as abundant nearby food sources and low egg predation rates.<ref name="Chronic Tidally-Induced Nest Failure in a Colony of White Ibises">{{Cite journal | last1 = Frederick | first1 = P. C. | title = Chronic Tidally-Induced Nest Failure in a Colony of White Ibises | journal = The Condor | volume = 89 | url=http://sora.unm.edu/node/103817| issue = 2 |jstor=1368495| pages = 413–419 | doi = 10.2307/1368495 | year = 1987 | url-access = subscription }}</ref>
[[File:Eudocimus albus -Winter Haven, Florida, USA -juvenile-8 (2).jpg|thumb|right|Juvenile in Florida]]
The eggs hatch after about three weeks and the young are attended by both parents. Males are present around the nest for most of the day, and females most of the night. The parents exchange nest duties in the morning and in the evening. Most of the feeding of the chicks occurs during the period where they swap nesting duties. Little feeding is done in the period of the day that is between the two duty swaps and no feeding is done between midnight and 6 a.m.<ref name=" Feeding Rhythm in Nestling White Ibis">{{Cite journal | last1 = Kushlan | first1 = J. A. | title = Feeding Rhythm in Nestling White Ibis | journal = The Wilson Bulletin | volume = 88 | issue = 4 | pages = 656–658 | jstor = 4160835| year = 1976 | url=http://sora.unm.edu/node/129337}}</ref> Chick mortality is highest in the first twenty days post hatching, with anywhere from 37 to 83% of hatchlings surviving to three weeks of age in the Everglades.<ref name=bnademographics/> During periods of food limitations and starvation events, the American white ibis tends to exhibit sex-dependent pre-fledgling mortality.<ref name="Sex-Related Mortality">{{cite journal |last1=Adams |first1=Evan M. |last2=Frederick |first2=Peter C. |title=Sex-related mortality of White Ibis (''Eudocimus albus'') nestlings during a starvation event |journal=Waterbirds |volume=32 |issue=1 |year=2009 |pages=123–127 |issn=1524-4695 |doi=10.1675/063.032.0114 |s2cid=86049097 |url=http://www.evergladeshub.com/lit/pdf09/Adams%2709bioOne-2-IbisMort.pdf }}</ref> For many bird species that have sexually dimorphic nestlings, mortality rates are higher for larger-sized male nestlings as a result of the parents' inability to meet its greater nutritional needs.<ref name="Parental investment and sex differences in juvenile mortality in birds and mammals">{{Cite journal | last1 = Clutton-Brock | first1 = T. H. | last2 = Albon | first2 = S. D. | last3 = Guinness | first3 = F. E. | doi = 10.1038/313131a0 | title = Parental Investment and Sex Differences in Juvenile Mortality in Birds and Mammals | journal = Nature | volume = 313 | issue = 5998 | pages = 131–33 | year = 1985 | bibcode = 1985Natur.313..131C | s2cid = 4355603 }}</ref> However, in the case of the American white ibis, the male nestlings actually have a lower mortality rate as compared to the females despite being on average 15% greater in mass as compared to its female counterparts.<ref name="Sex-Related Mortality" /> Although current research has yet to discover the underlying factors to why the males tend to have better survival rates under such conditions, it is suspected that the parents tend to feed the larger male nestlings first because they are either perceived by the parents to have a higher chance of survival, or, being generally larger, the male nestlings simply out-compete the small females for food.<ref name="Parental investment and sex differences in juvenile mortality in birds and mammals" />
Bird predators may seize anywhere from 7% to 75% of the progeny in a breeding colony.<ref name=bnabehaviour/> The [[fish crow]] (''Corvus ossifragus'') is common raider of American white ibis nests, accounting for up to 44% of egg loss in a field study at Battery Island, North Carolina.<ref name= "Fish Crow Predation on Eggs of the White Ibis at Battery Island, North Carolina">{{Cite journal | last1 = Shields | first1 = M. A. | last2 = Parnell | first2 = J. F. | title = Fish Crow Predation on Eggs of the White Ibis at Battery Island, North Carolina | journal = The Auk | volume = 103 | issue = 3 | pages = 531–539 | year = 1986 | url=http://sora.unm.edu/node/24283|jstor= 4087124 | doi = 10.1093/auk/103.3.531 | url-access = subscription }}</ref> Other predators of eggs and young include the [[boat-tailed grackle]] (''Quiscalus major''), [[black-crowned night heron]] (''Nycticorax nycticorax''), gulls, and possibly vultures, as well as the [[common opossum]] (''Didelphis marsupialis''), [[raccoon]] (''Procyon lotor''), and rat snakes (''[[Elaphe]]'' species).<ref name=bnabehaviour/><!-- cites previous two sentences --> Egg predation rates of the American white ibis decline with nest age owing to increased nest attentiveness by the parents, especially during the last week of incubation. High nest densities and reduced synchrony increase egg predation rates because of the increased opportunities afforded by the longer incubation times, as well as the greater availability of nests available for predation.<ref name= "Fish Crow Predation on Eggs of the White Ibis at Battery Island, North Carolina"/>
The American white ibis begins breeding in its third summer, although birds in captivity may breed as young as nine or ten months of age.<ref name=bnademographics/> The oldest member of the species recorded in captivity was over 20 years of age, and a wild bird has been picked up 16 years and 4 months after being [[Bird ringing|banded]].<ref name="Nellis01"/>
===Diet===
[[File:Eudocimus albus -USA -eating a fish-8.jpg|left|thumb|Adult eating a fish]]
The American white ibis prefers to eat [[crayfish]] and other [[crustacean]]s, but also takes [[aquatic insect]]s and small fish.<ref name="White Ibis | National Audubon Society Birds" /><ref name="Estimation of crayfish abundance and size-structure in diets of White Ibis chicks">{{Cite journal | last1 = Dorn | first1 = Nathan J. | last2 = Herring | first2 = Garth | last3 = Gawlik | first3 = Dale E. | doi = 10.1675/1524-4695-31.3.417 | title = Estimation of Crayfish Abundance and Size-structure in Diets of White Ibis Chicks | journal = Waterbirds | volume = 31 | issue = 3 | pages = 417–23 | year = 2008 | s2cid = 86083371 }}</ref> Outside the nesting season, the diet is highly variable, as abundance and types of prey depend on both the region and the [[habitat]]. In the [[Llanos]], located in Colombia and Venezuela, the most frequent prey are [[insects]], such as fly larvae and beetles. Generally in North America the main prey are crustaceans, mostly crayfish.<ref name=" Food Habits of the Scarlet and White Ibis in the Orinoco Plains">{{Cite journal | last1 = Aguilera | first1 = E.| last2 = Ramo | first2 = C. | last3 = Busto | first3 = B. | title = Food Habits of the Scarlet and White Ibis in the Orinoco Plains | journal = The Condor | volume = 95 | issue = 3 | pages = 739–741 | doi = 10.2307/1369623 |jstor=1369623| year = 1993 | url=http://sora.unm.edu/node/104765
| url-access = subscription }}</ref> In the [[Everglades]] and cypress swamps, the diet is primarily made up of crayfish, while those that feed in willow ponds eat predominantly fish. American white ibises that feed in mangrove swamps focus on crabs.<ref name="Feeding Ecology and Prey Selection in the White Ibis" /> The tactile nature of the ibis's probing for food in mud means that it catches prey that are too slow to evade the ibis once located by its bill. In the Everglades, this means that crayfish make up a large part of the diet, but a more diverse array of invertebrates are taken in coastal areas.<ref name=" Prey Choice by Tactile-Foraging Wading Birds">{{Cite journal | last1 = Kushlan | first1 = James A. | title = Prey Choice by Tactile-Foraging Wading Birds | journal = Proceedings of the Colonial Waterbird Group | volume = 3 | pages = 133–42 | year = 1980 | jstor = 4626707 }}</ref> Although crayfish are sought by foraging ibises, [[prey switching]] to fish does occur if fish are found in great abundance. It is unclear whether the fish are more easily caught if overcrowded, or whether sheer numbers of fish mean that ibises are catching them instead of crayfish—normally, fish are more agile than crayfish and hence elude the ibis's bill more easily. Fish are a more energy-rich source of food for the American white ibis.<ref name="Feeding Ecology and Prey Selection in the White Ibis" /> In the breeding season, American white ibises in a colony at Pumpkinseed Island travelled further to forage in freshwater wetlands and catch crayfish, than nearby saltwater areas where [[fiddler crab]]s predominated, indicating their benefit was worth the extra energy expended in fetching them for their young.<ref>{{cite journal |last1=De Santo |first1=Toni L. |last2=Johnston |first2=James W. |last3=Bildstein |first3=Keith L. |title=Wetland Feeding Site Use by White Ibises (''Eudocimus albus'') Breeding in Coastal South Carolina |journal=Colonial Waterbirds |volume=20 |issue=2 |pages=167–176 |doi=10.2307/1521683 |year=1997|jstor=1521683 }}</ref> This travel results in the wholesale transport of nutrients across the landscape by the colony; in a successful breeding year the colony at Pumpkinseed Island was estimated to have contributed a third as much [[phosphorus]] to the neighboring estuary as other environmental processes.<ref>{{cite journal |last1=Bildstein |first1=Keith L. |last2=Blood |first2=Elizabeth |last3=Frederick |first3=Peter |title=The relative importance of biotic and abiotic vectors in nutrient transport |journal=Estuaries |volume=15 |issue=2 |year=1992 |pages=147 |issn=0160-8347 |doi=10.2307/1352688 |url=http://www.wec.ufl.edu/faculty/FrederickP/publications/Bildstein%20et%20al%2092%20Relative%20importance%20of%20biotic%20and%20abiotic%20vectors.pdf |jstor=1352688 |s2cid=2098638 }}</ref>
The American white ibis is found in [[mixed-species foraging flock]]s with the [[glossy ibis]] (''Plegadis falcinellus'') in flooded fields, and the two species select different food items with little overlap; the former foraging for [[crab]]s and aquatic insects and the latter feeding mainly on grain.<ref name="Nellis01"/> The wood stork is also found in the same habitat in Florida, but hunts larger prey and a higher percentage of fish, so there is little overlap.<ref name=" Prey Choice by Tactile-Foraging Wading Birds"/> In the Llanos, where American white ibis coexist with the scarlet ibis, their diets differ, the former consuming more [[Heteroptera|bugs]], fish and crustaceans, while the latter eat a much higher proportion of [[beetle]]s.<ref name=" Food Habits of the Scarlet and White Ibis in the Orinoco Plains"/> The [[willet]] (''Tringa semipalmata'') has been observed trailing American white ibis and catching prey disturbed by them, and even [[Kleptoparasitism|kleptoparasitizing]] (stealing) from them, in [[J. N. "Ding" Darling National Wildlife Refuge]] on [[Sanibel Island]] in Florida.<ref>{{cite journal |title=Willets Kleptoparasitize and Use White Ibis as "Beaters" |last1=Davis |first1=William E. Jr. |last2=Jackson |first2=Jerome A. |journal=Wilson Journal of Ornithology |volume=119 |issue=4 |pages=758–760 |doi=10.1676/06-047.1 |year=2007|s2cid=85090489 }}</ref> An isolated event of [[wikt:intraspecific|intraspecific]] predation in juvenile American white ibis has been observed, where a juvenile attacked and consumed a chick from another nest.<ref name="Herring, G., Johnston, M. D. & Call, E. M. 2005. Intraspecific predation in juvenile White Ibis">{{Cite journal | last1 = Herring | first1 = Garth| last2 = Johnston | first2 = Mark D. | last3 = Call | first3 = Erynn M. | title = Intraspecific Predation in Juvenile White Ibis | journal = Waterbirds | volume = 28 | issue = 4 | pages = 531–32 | year = 2005 | doi = 10.1675/1524-4695(2005)28[531:IPIJWI]2.0.CO;2 | s2cid = 85632181}}</ref>
===Foraging===
[[File:Eudocimus albus -Bonita Beach, Bonita Springs, Florida, USA-8.ogv|thumbtime=1|thumb|Video of adults foraging on Bonita Beach in [[Bonita Springs, Florida]]]]
[[File:Eudocimus albus -Port Orange, Florida, Florida, USA-8.jpg|thumb|Adult white ibis foraging for food in a front garden in [[Port Orange, Florida]]]]
During the summer, the American white ibis roams along the coast of tidal flats and mangrove swamps as the inland marshes are usually flooded. However, as the water level recedes in the fall, populations at the coast shift their foraging area inland, to inland marshes and swamplands.<ref name="Feeding Ecology and Prey Selection in the White Ibis" /> It has become more common in urban landscapes in Florida since the late 1990s,<ref>{{cite web |url=http://myfwc.com/media/1352386/White%20Ibis%20Supplemental%20Information.pdf |title=Supplemental Information for the White Ibis: Biological Status Review Report |last1=Kushlan |first1=Jim |date=31 March 2011 |publisher=Florida Fish and Wildlife Conservation Commission |pages=3 |access-date=25 December 2011 |___location= Tallahassee, Florida |archive-url=https://web.archive.org/web/20120721225313/http://myfwc.com/media/1352386/White%20Ibis%20Supplemental%20Information.pdf |archive-date=21 July 2012}}</ref> and is one of a number of wetland-dependent bird species which forages in man-made ponds on golf courses in the southwest of the state.<ref>{{cite web |url=http://edis.ifas.ufl.edu/pdffiles/UW/UW20700.pdf |title=WEC188: Wildlife in Urban Landscapes: Use of Golf Course Ponds by Wetlands Birds |last1=White |first1=C. LeAnn |last2=Main |first2=Martin B. |date=August 2009 |publisher=Institute of Food and Agricultural Sciences (IFAS), University of Florida |___location=Gainesville, Florida |access-date=25 December 2011}}</ref>
The American white ibis is a [[Touch|tactile]], nonvisual forager, which limits its ability to choose from a wide variety of prey.<ref name="Foraging Behavior of the White Ibis">{{Cite journal | last1 = Kushlan | first1 = J. A. | title = Foraging Behavior of the White Ibis | journal = The Wilson Bulletin | volume = 89 | issue = 2 | pages = 342–345 | year = 1977 | url=http://sora.unm.edu/node/129411| jstor = 4160923}}</ref> For the most part, the American white ibis forages for food by tactile probing. It wades slowly through shallow water and sticks its long, downcurved [[beak|bill]] into the [[Substrate (marine biology)|substrate]] of the water body with its bill held at around {{convert|1|to|2|cm|in|abbr=on}} agape at the tip, and sweeps its long bill back and forth across the bottom to pick out suitable food items.<ref name="White Ibis, Identification, All About Birds" /> Birds may also probe when standing still. Groping with a wide open bill is a technique used by ibis in deeper water when alone, as is head swinging, in which the ibis swings its wide open bill widely in open water. Others copy this type of foraging if they see one ibis doing it. On land, the American white ibis locates prey by sight and pecks, and does not have to insert its bill into the substrate.<ref name="Foraging Behavior of the White Ibis"/> The American white ibis seeks small prey when other birds are around, as it needs time to break up larger food items into smaller pieces to eat, and other predators such as herons and [[egret]]s often take the opportunity to rob the ibis of its catch.<ref name="Feeding Ecology and Prey Selection in the White Ibis" /><ref name=" Foraging Associates of White Ibis">{{Cite journal | last1 = Courser | first1 = W. D. | last2 = Dinsmore | first2 = J. J. | title = Foraging Associates of White Ibis | journal = The Auk | volume = 92 | issue = 3 | pages = 599–601 | doi = 10.2307/4084623| year = 1975 | url=http://sora.unm.edu/node/22723| jstor = 4084623| url-access = subscription }}</ref> Along with the scarlet ibis, the species coexists with another five species of ibis in the Llanos in Venezuela. American white ibis males are aggressive to and take prey items from smaller ibises, but the smaller females are more often the victims of this behavior.<ref>{{cite journal |title=Foraging Ecology of Seven Species of Neotropical Ibises (Threskiornithidae) during the Dry Season in the Llanos of Venezuela |last1=Frederick |first1=Peter C. |last2=Bildstein |first2=Keith L |journal=The Wilson Bulletin |volume=104 |issue=1 |pages=1–21}}</ref>
Juveniles have lower foraging efficiency compared to adults and in most feeding flocks, the juveniles are usually outnumbered by the adults. They usually tend to stay close to one another and forage for food together at the peripheral region of the group.<ref name=" Age-Related Differences in the Flocking and Foraging Behavior of White Ibises In a South Carolina Salt Marsh.">{{Cite journal | last1 = Bildstein | first1 = Keith L. | title = Age-Related Differences in the Flocking and Foraging Behavior of White Ibises in a South Carolina Salt Marsh | journal = Colonial Waterbirds | volume = 6 | doi = 10.2307/1520966 | pages = 45–53 | year = 1983 | jstor = 1520966 }}</ref> During the breeding season, adult male ibises have been recorded raiding other parent ibises who are feeding their young in the colony. The raiders force their bill down the throat of the victim—either the parent about to disgorge their food or recently fed young—and extract the ball of food.<ref name="Intraspecific Food Piracy in the White Ibis">{{Cite journal | last1 = Frederick | first1 = P. C. | title = Intraspecific Food Piracy in White Ibis | journal = Journal of Field Ornithology | volume = 56 | issue = 4 | pages = 413–414 | year = 1985 |jstor= 4513062| url=http://sora.unm.edu/node/51218}}</ref> This behavior allows the otherwise starving adult males to obtain food without having to spend long periods of time away from the nest, and prevent its female mate copulating with another male ibis, which would reduce its own reproductive success. Females and juveniles almost never try to drive off the larger and more aggressive pirating males, but instead try to avoid or move away from them.<ref name="Intraspecific Food Piracy in the White Ibis" /> This pirating behavior is less common between two male ibises as the males will actively fight off the pirate.<ref name="Intraspecific Food Piracy in the White Ibis" /> The explanation of the species' [[sexual dimorphism]] of body size is unclear, because no differences between the sexes in feeding success rates or the foraging behavior have been observed and, as males are larger, they need more food than females.<ref name="Energetic Consequences of Sexual Size Dimorphism in White Ibises (''Eudocimus albus'')">{{Cite journal | last1 = Bildstein | first1 = K. L. | title = Energetic Consequences of Sexual Size Dimorphism in White Ibises (''Eudocimus albus'') | journal = The Auk | volume = 104 | issue = 4 | pages = 771–775 | year = 1987 | url=http://sora.unm.edu/node/24495| jstor = 4087293| doi = 10.1093/auk/104.4.771 | url-access = subscription }}</ref>
==Parasites and mortality==
Causes of death of adult ibis are not well known. [[American alligator|Alligators]] could feasibly prey on nesting ibises but there has been little research in the area.<ref name=bnademographics/> A flock of fifty adult American white ibis were killed in a fire in the Everglades. The corpses were found in a dense swathe of cattail (''[[Typha angustifolia]]''), which suggested they had taken shelter there. It is unclear why they had not been able to fly away from the fire, but one hypothesis was that they had been foraging for insects disturbed by the fire.<ref>{{cite journal |last1=Epanchin |first1=Peter N. |last2=Heath |first2=Julie A. |last3=Frederick |first3=Peter C. |year=2002 |title=Effects of Fires on Foraging and Breeding Wading Birds in the Everglades |journal=The Wilson Bulletin |volume=114 |issue=1 |pages=139–141 |url=http://www.wec.ufl.edu/faculty/frederickp/publications/Epanchin%20et%20al%2002%20Effects%20of%20Everglades%20fires%20on%20wading%20bird%20colonies.pdf|jstor=4164426|doi=10.1676/0043-5643(2002)114[0139:EOFOFA]2.0.CO;2|s2cid=86393745 }}</ref>
A total of 51 species of [[parasitic worm]] have been recovered from the American white ibis, predominantly from the [[gastrointestinal system]] and particularly the [[small intestine]]. These include [[Cestoda]] (tapeworms), [[Acanthocephala]] (thorny headed worms), [[Nematode|Nematoda]] (roundworms), [[Digenea]] and [[Spirurida]]. Several roundworm and spirurid species have been found in the lining of the [[gizzard]].<ref>{{cite journal |title=''Patagifer lamothei'' n. sp (Digenea: Echinostomatidae: Nephrostominae) From the White Ibis ''Eudocimus albus'' (Threskiornithidae) from Texas, USA |last1=Dronen |first1=Norman O. |last2=Blend |first2=Charles K. |journal= Revista Mexicana de Biodiversidad |volume=79 |pages=23S–32S |year=2008}}</ref> Nematodes are more prevalent in American white ibis from freshwater habitats, and cestodes more frequent in those from saltwater areas. One nematode found in adult birds, ''[[Skrjabinoclavia thapari]]'', is borne in the fiddler crab as an [[intermediate host]], while the thorny headed worm species ''[[Southwellina dimorpha]]'' is carried in crayfish and infests both adult and juvenile ibis.<ref name=bnademographics/>
Parasitic protozoa of the genus ''[[Sarcocystis]]'' have been recovered from the [[smooth muscle]]s of adult American white ibis,<ref>{{cite journal |last1=Spalding |first1=Marilyn G. |last2=Atkinson |first2=Carter T. |last3=Carleton |first3=Renee E. |year=1994 |title=''Sarcocystis'' sp. in Wading Birds (Ciconiiformes) from Florida |journal=Journal of Wildlife Diseases |volume=30 |issue=1 |pages=29–35 |pmid=8151820 |doi=10.7589/0090-3558-30.1.29|s2cid=10825846 }}</ref> and another species, ''[[Haemoproteus plataleae]]'', has been recovered from the blood of adults and nestlings, and can hence be transmitted before the young leave the nest.<ref name=forrester80>{{Cite journal| last1 = Forrester | first1 = Donald J.| title = Hematozoa and Mallophaga from the White Ibis, ''Eudocimus albus'' L., in Florida| journal = The Journal of Parasitology| volume = 66| issue = 1| pages = 58–59| doi = 10.2307/3280589| year = 1980| pmid = 6767833| jstor = 3280589}}</ref><ref>{{Cite journal | last1 = Telford Jr. | first1 = Sam R. | last2 = Spalding | first2 = Marilyn G. | last3 = Forrester | first3 = Donald J. | doi = 10.1139/z92-196 | title = Hemoparasites of Wading Birds (Ciconiiformes) in Florida | journal = Canadian Journal of Zoology | volume = 70 | issue = 7 | pages = 1397–1408 | year = 1992 | bibcode = 1992CaJZ...70.1397T }}</ref> The larvae of two species of [[mite]] of the family [[Hypoderidae]], ''[[Phalacrodectes whartoni]]'' and ''[[Neoattialges eudocimae]]'', have been recovered from under the skin.<ref>{{cite journal |last=Pence |first=Danny B. |year=1971 |title=The Hypopi (Acarina: Hypoderidae) from the Subcutaneous Tissues of the White Ibis, ''Eudocimus albus'' L |journal=The Journal of Parasitology |volume=57 |issue=6 |pages=1321–1323 |doi=10.2307/3277992|jstor=3277992 |pmid=5146454 }}</ref> Two species of the [[louse]] suborder [[Mallophaga]], ''[[Plegadiphilus eudocimus]]'' and ''[[Ardeicola robusta]]'', also parasitise the bird.<ref name=forrester80/>
==Status==
The American white ibis is classed as being of [[least concern]] on the [[IUCN Red List]].<ref name="IUCN" /> The population consists of 150,000 mature adults, and is stable, although some populations have unknown trends. A partial survey of under 50% of the North American population published in 2007 found an almost six-fold increase in the last four decades. The estimated breeding range is huge, at {{convert|1200000|km2|sqmi|abbr=on}}.<ref name = BirdLife>{{cite web |title=BirdLife International Species Factsheet: ''Eudocimus albus'' |publisher=BirdLife International |url=http://www.birdlife.org/datazone/speciesfactsheet.php?id=3774 |access-date=19 May 2011 }}</ref> Fluctuating breeding populations and high mobility of colonies make estimating the population difficult. Attempted censuses of breeding colonies across Texas, Louisiana, Florida, and the Carolinas yielded a count of 166,000 breeding birds in 2001, and 209,000 in 2004.<ref name=bnademographics/> The conservation status has been listed in two states—it is a ''Species of Special Concern'' in Florida, and a species of ''Moderate Conservation Concern'' in Alabama. The preservation of colony sites and freshwater foraging areas is important to maintaining populations; however, the highly mobile nature of breeding colonies makes this challenging.<ref name=bnademographics/><!-- cites previous two sentences -->
===Human impact===
[[John James Audubon]] reported that the American white ibis was hunted and sold in Louisiana, and mainly eaten by American Indians. It had orange flesh and a strong fishy taste.<ref name=JAA/> Elsewhere, the flesh has been described as appealing on account of the crayfish diet, and both members of the genus ''Eudocimus'' have been hunted, which has been responsible for decline, across their range.<ref name=Hancock10/> Crawfish farmers in Louisiana have also shot them for foraging in crawfish ponds. Overall, the impact of hunting is not thought to be major.<ref name=bnademographics/>
The pollutant [[methylmercury]] is a globally distributed [[neurotoxin]] and an [[endocrine system]] disruptor. In the [[Everglades]] ecosystem, human pollution has led to increased concentrations of methylmercury, which have impacted the behaviors of the American white ibis.<ref name="Relationships among mercury concentrations, hormones, and nesting efforts of White Ibises (Eudocimus Albus) in the Florida everglades">{{Cite journal | last1 = Heath | first1 = J. A. | last2 = Frederick | first2 = P. C. | title = Relationships among Mercury Concentrations, Hormones, and Nesting Effort of White Ibises (''Eudocimus albus'') in the Florida Everglades (Relaciones entre las Concentraciones de Mercurio, Hormonas y el Esfuerzo de Nidificación de Eudocimus albus en los Everglades, Florida) | journal = The Auk | volume = 122 | issue = 1 | pages = 255–267 | doi = 10.1642/0004-8038(2005)122[0255:RAMCHA]2.0.CO;2| year = 2005 | s2cid = 19064976 | url = http://www.wec.ufl.edu/faculty/frederickp/publications/Heath%20Frederick%2005%20relationships%20among%20mercury%20concentrations%20hormones%20and%20nesting%20effort.pdf}}</ref> [[Hormone]] levels in males are affected, leading to a decrease in the rates of key courtship behavior, and fewer approaches by females during the mating season.<ref name="Altered pairing behavior and reproductive success in White Ibises exposed to environmentally relevant concentrations of methylmercury">{{Cite journal | last1 = Frederick | first1 = Peter | last2 = Jayasena | first2 = Nilmini| title = Altered Pairing Behaviour and Reproductive Success in White Ibises Exposed to Environmentally Relevant Concentrations of Methylmercury | doi = 10.1098/rspb.2010.2189 | journal = Proceedings of the Royal Society B: Biological Sciences |volume=278|issue=1713|pages=1851–57| year = 2011 | pmid = 21123262| pmc = 3097836}}</ref> In addition, methylmercury also increased male-male pairing behaviors by 55%. Both the chemically induced "homosexual" behavior and the diminished ability to attract females by males have reduced reproduction rates in affected populations.<ref name="Altered pairing behavior and reproductive success in White Ibises exposed to environmentally relevant concentrations of methylmercury" /> Exposure of American white ibises to methylmercury causes reduced foraging efficiency<ref name="Effects of Methylmercury and spatial complexity on the foraging behavior and foraging efficiency in juvenile White Ibises (Eudocimus albus)">{{Cite journal | last1 = Adams | first1 = E. M. | last2 = Frederick | first2 = P. C. | doi = 10.1897/07-466.1 | title = Effects of Methylmercury and Spatial Complexity on Foraging Behavior and Foraging Efficiency in Juvenile White Ibises (''Eudocimus albus'') | journal = Environmental Toxicology and Chemistry | volume = 27 | issue = 8 | pages = 1708–1712 | year = 2008 | pmid = 18315390| bibcode = 2008EnvTC..27.1708A | s2cid = 86506587 | url= http://www.wec.ufl.edu/faculty/frederickp/publications/Adams%20Frederick%2008%20Effects%20of%20methylmercury%20and%20spatial%20complexity.pdf}}</ref> and it also makes them more likely to abandon nests owing to the disruptive effect of the pollutant on the bird's hormone systems, which in turn affects parental care behavior.<ref name="Relationships among mercury concentrations, hormones, and nesting efforts of White Ibises (Eudocimus Albus) in the Florida everglades" /> Tests on captive birds have not shown a decreased survival of American white ibis exposed to methylmercury.<ref>{{Cite journal | last1 = Frederick | first1 = P.| last2 = Campbell | first2 = A. | last3 = Jayasena | first3 = N. | last4 = Borkhataria | first4 = R.| title = Survival of White Ibises (''Eudocimus albus'') in Response to Chronic Experimental Methylmercury Exposure | doi = 10.1007/s10646-010-0586-9 | journal = Ecotoxicology | volume = 20 | issue = 2 | pages = 358–364 | year = 2010 | pmid = 21184176| s2cid = 80437}}</ref>
==In culture==
{{Further|Sebastian the Ibis}}
[[Native American mythology|Native American folklore]] held that the bird was the last to seek shelter before a hurricane, and the first to emerge afterwards. The bird was thus a symbol for danger and optimism.<ref name="na">{{cite web |title=The Tale of the Ibis |last=Blitman |first=Andrew |date=26 October 2008 |work=The Miami Hurricane |url=http://www.themiamihurricane.com/2008/10/26/the-tale-of-the-ibis/ |access-date=14 October 2011}}</ref> For this reason, the [[University of Miami]] adopted the American white ibis as its official athletics [[mascot]] in 1926,<ref name="The Tradition Of the Ibis">{{cite web|url=http://hurricanesports.cstv.com/genrel/010600aaa.html |title=The Tradition Of The Ibis: School Mascot Represents Leadership, Courage and Strength of Miami Student-athletes |year=2011 |work=HurricaneSports.com – The University of Miami Official Athletic Site |publisher=University of Miami |access-date=16 May 2011 |url-status=dead |archive-url=https://web.archive.org/web/20110310184024/http://hurricanesports.cstv.com/genrel/010600aaa.html |archive-date=10 March 2011 }}</ref> and the [[yearbook]] was known as ''The Ibis'' from that year.<ref name="na" /><!-- cites two previous sentences--> The mascot was initially known as Ibis before adopting the name [[Sebastian the Ibis|Sebastian]] in 1957. It was named after San Sebastian Hall, a residence hall on campus, which sponsored an Ibis entry in the college's homecoming celebration.<ref name="HurricaneSports.com - The University of Miami Official Athletic Site">{{cite web|url=http://hurricanesports.cstv.com/trads/mifl-mascot.html |title=Sebastian the Ibis |work=HurricaneSports.com – The University of Miami Official Athletic Site |publisher=University of Miami |access-date=16 May 2011 |url-status=dead |archive-url=https://web.archive.org/web/20110519081217/http://hurricanesports.cstv.com/trads/mifl-mascot.html |archive-date=19 May 2011 }}</ref>
==References==
{{Reflist|colwidth=30em}}
==External links==
{{Commons category|Eudocimus albus}}
{{Wikispecies|Eudocimus albus}}
* [https://web.archive.org/web/20120117132114/http://www.arkive.org/white-ibis/eudocimus-albus/#src=portletV3api American white ibises on Arkive]. Shows videos made by the [[BBC]] natural history unit.
* {{EBirdSpecies|whiibi|White Ibis}}
* {{VIREO|white+ibis|White ibis}}
* {{NeotropicalBirds|whiibi|White ibis}}
{{Featured article}}
{{Threskiornithidae}}
{{portalbar|Birds|Animals|Biology}}
{{Taxonbar|from=Q589171}}
[[Category:Eudocimus|American white ibis]]
[[Category:Birds of the Americas]]
[[Category:Native birds of the Southeastern United States]]
[[Category:Birds of Central America]]
[[Category:Birds of the Dominican Republic]]
[[Category:Birds of Colombia]]
[[Category:Birds of Venezuela]]
[[Category:Birds of Ecuador]]
[[Category:Ibises]]
[[Category:Wading birds|Ibis, American White]]
[[Category:Articles containing video clips]]
[[Category:Birds described in 1758|American white ibis]]
[[Category:Animal taxa named by Carl Linnaeus|American white ibis]]
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