Rostrhamus sociabilis

Life-forms

Superregnum: Eukaryota
Cladus: Unikonta
Cladus: Opisthokonta
Cladus: Holozoa
Regnum: Animalia
Subregnum: Eumetazoa
Cladus: Bilateria
Cladus: Nephrozoa
Superphylum: Deuterostomia
Phylum: Chordata
Subphylum: Vertebrata
Infraphylum: Gnathostomata
Megaclassis: Osteichthyes
Cladus: Sarcopterygii
Cladus: Rhipidistia
Cladus: Tetrapodomorpha
Cladus: Eotetrapodiformes
Cladus: Elpistostegalia
Superclassis: Tetrapoda
Cladus: Reptiliomorpha
Cladus: Amniota
Classis: Reptilia
Cladus: Eureptilia
Cladus: Romeriida
Subclassis: Diapsida
Cladus: Sauria
Infraclassis: Archosauromorpha
Cladus: Crurotarsi
Divisio: Archosauria
Cladus: Avemetatarsalia
Cladus: Ornithodira
Subtaxon: Dinosauromorpha
Cladus: Dinosauriformes
Cladus: Dracohors
Cladus: Dinosauria
Ordo: Saurischia
Cladus: Eusaurischia
Subordo: Theropoda
Cladus: Neotheropoda
Cladus: Averostra
Cladus: Tetanurae
Cladus: Avetheropoda
Cladus: Coelurosauria
Cladus: Tyrannoraptora
Cladus: Maniraptoromorpha
Cladus: Maniraptoriformes
Cladus: Maniraptora
Cladus: Pennaraptora
Cladus: Paraves
Cladus: Eumaniraptora
Cladus: Avialae
Infraclassis: Aves
Cladus: Avebrevicauda
Cladus: Pygostylia
Cladus: Ornithothoraces
Cladus: Ornithuromorpha
Cladus: Carinatae
Parvclassis: Neornithes
Cohors: Neognathae
Cladus: Neoaves
Ordo: Accipitriformes

Familia: Accipitridae
Subfamilia: Milvinae
Genus: Rostrhamus
Species: Rostrhamus sociabilis
Subspecies: R. s. levis – R. s. major – R. s. plumbeus – R. s. sociabilis
Name

Rostrhamus sociabilis (Vieillot, 1817)
Synonymy

Herpetotheres sociabilis (protonym)

References

Vieillot, L.P. 1817. Nouveau Dictionnaire d’Histoire naturelle, appliquée aux arts, à l'agriculture, à l'économie rurale et domestique, à la médecine, etc. Par une société de naturalistes et d'agriculteurs. Avec des figures tirées des trois règnes de la nature. Tome 18. 542 pp. + 6 tt. Déterville, Paris. p. 318 BHL Reference page.

Vernacular names
العربية: حدأة الحلزون
български: Охлювоядна каня
català: Caragoler comú
čeština: Luněc bažinný
Cymraeg: Barcud malwod
dansk: Snegleglente
Deutsch: Schneckenweih
English: Snail Kite
Esperanto: Helikomilvo
español: Caracolero común
eesti: Teohaugas
suomi: Kotilohaukka
français: Milan des marais
Avañe'ẽ: Taguato jatyta
עברית: דיית החלזונות
magyar: Szalagos csigászkánya
italiano: Nibbio delle Everglades
日本語: タンニシトビ
Nederlands: Slakkenwouw
norsk: Snegleglente
Diné bizaad: Chʼiltaalkʼę́hé binááʼ łichíʼígíí
polski: Ślimakojad czerwonooki
português do Brasil: Gavião-caramujeiro
português: Gavião-caramujeiro
română: Uliul moluștelor
русский: Коршун-слизнеед
slovenčina: Hákozobec družný
svenska: Snäckglada
ไทย: นกเหยี่ยวกินหอยทาก
українська: Шуліка-слимакоїд червоноокий
Tiếng Việt: Diều ăn sên
中文: 食螺鸢

The snail kite (Rostrhamus sociabilis) is a bird of prey within the family Accipitridae, which also includes the eagles, hawks, and Old World vultures. Its relative, the slender-billed kite, is now again placed in Helicolestes, making the genus Rostrhamus monotypic. Usually, it is placed in the Milvine kites, but the validity of that grouping is under investigation.
Description
Juvenile
Female Snail Kite, Lake Okeechobee, Florida
Male Snail Kite, Lake Okeechobee, Florida

Snail kites are 36 to 48 cm (14 to 19 in) long with a 99–120 cm (39–47 in) wingspan. They weigh from 300 to 570 g (11 to 20 oz).[3][4] There is very limited sexual dimorphism, with the female averaging only 3% larger than the male. They have long, broad, and rounded wings, which measure 29–33 cm (11–13 in) each. Its tail is long, at 16–21 cm (6.3–8.3 in), with a white rump and undertail coverts. The dark, deeply hooked beak, measuring 2.9–4 cm (1.1–1.6 in) is an adaptation to its diet. The tarsus is relatively long as well, measuring 3.6–5.7 cm (1.4–2.2 in).[4]

The adult male has dark blue-gray plumage with darker flight feathers. The legs and cere are red. The adult female has dark brown upperparts and heavily streaked pale underparts. She has a whitish face with darker areas behind and above the eye. The legs and cere are yellow or orange. The juvenile is similar to an adult female, but the crown is streaked. Adults have red or orangish-brown irises, while juveniles have dark brown irises.[5]

It flies slowly with its head facing downwards, looking for its main food, the large apple snails. For this reason, it is considered a molluscivore.
Taxonomy

Lerner and Mindell (2005) found R. sociabilis sister to Geranospiza caerulescens, and that those two along with Ictinea plumbea were basal to both the Buteogallus and Buteo clades. They concluded that Rostrhamus belonged in Buteoninae (sensu stricto) and not in Milvinae, but noted that more investigation was needed.[6]
Distribution

The snail kite breeds in tropical South America, the Caribbean, and central and southern Florida in the United States. It is resident all-year round in most of its range, but the southernmost population migrates north in winter and the Caribbean birds disperse widely outside the breeding season.
Breeding

It nests in a bush or on the ground, laying three to four eggs.
Conservation
Adult male Everglades snail kite in Joe Overstreet Landing, Florida.

The snail kite is a locally endangered species in the Florida Everglades, with a population of less than 400 breeding pairs. Research has demonstrated that water-level control in the Everglades is depleting the population of apple snails.[7] However, this species is not generally threatened over its extensive range.

In fact, it might be locally increasing in numbers, such as in Central America. In El Salvador, it was first recorded in 1996. Since then, it has been regularly sighted, including immature birds, suggesting a resident breeding population might already exist in that country. On the other hand, most records are outside the breeding season, more indicative of post-breeding dispersal. In El Salvador, the species can be observed during the winter months at Embalse Cerrón Grande, Laguna El Jocotal, and especially Lago de Güija. Pomacea flagellata apple snails were propagated in El Salvador between 1982 and 1986 as food for fish stocks, and it seems that the widespread presence of high numbers of these snails has not gone unnoticed by the snail kite.[8]
In the Everglades

Due to the drainage and habitat destruction of the Everglades, they were one of the first species put on the US Fish and Wildlife Service's endangered species list[9] on 11 March 1967.[10] The snail kite continued to decline, reaching a population of less than 800 in 2007. Their population gradually rebounded after the invasive snail species Pomacea maculata began to flourish in the Everglades wetlands and served as a new food source for the snail kites, reaching a count of 3,000 snail kites in 2022. Everglades conservation efforts over the course of 30 years and costing over US$20 billion also contributed to restoring native vegetation of the snail kites' habitats and flow of water in marshes.[9]
Diet

This is a gregarious bird of freshwater wetlands, forming large winter roosts. Its diet consists almost exclusively of apple snails, especially the species Pomacea paludosa in Florida, and species of the genus Marisa.[11][12]

Snail kites have been observed eating other prey items in Florida, including crayfish in the genus Procambarus, crabs in the genus Dilocarcinus, black crappie, small turtles and rodents.[13][12][11] It is believed that snail kites turn to these alternatives only when apple snails become scarce, such as during drought,[14] but further study is needed. On 14 May 2007, a birder photographed a snail kite feeding at a red swamp crayfish farm in Clarendon County, South Carolina.[15][16]

The presence of the large introduced Pomacea maculata in Florida has led the snail kites in North America to develop larger bodies and beaks to better eat the snail, a case of rapid evolution.[17] These non-native snails provide a better food source than the smaller native snails and have had a positive effect on the kites' populations.[18]
References

BirdLife International (2020). "Rostrhamus sociabilis". IUCN Red List of Threatened Species. 2020: e.T22695048A168999707. doi:10.2305/IUCN.UK.2020-3.RLTS.T22695048A168999707.en. Retrieved 25 September 2021.
Gill F, D Donsker & P Rasmussen (Eds). 2020. IOC World Bird List (v10.2). doi : 10.14344/IOC.ML.10.2.
"Snail Kite". All About Birds. Cornell Lab of Ornithology.
Ferguson-Lees, J.; Christie, David A. (2001). Raptors of the world: Snail Kite. Houghton Mifflin. pp. 363–365. ISBN 978-0618127627.
"All About Snail Kites". Sharp-Eatman Nature Photography. Retrieved 26 January 2021.
Lerner, H.R.L.; Mindell, D.P. (2005). "Phylogeny of eagles, Old World vultures and other Accipitridae based on nuclear and mitochondrial DNA" (PDF). Molecular Phylogenetics and Evolution. 37 (2): 327–346. doi:10.1016/j.ympev.2005.04.010. PMID 15925523.
"Lake Okeechobee Low Lake Stage Restoration Projects". Archived from the original on 4 June 2010.
Herrera, Néstor; Rivera, Roberto; Ibarra Portillo, Ricardo; Rodríguez, Wilfredo (2006). "Nuevos registros para la avifauna de El Salvador" [New records for the avifauna of El Salvador] (PDF). Boletín de la Sociedad Antioqueña de Ornitología (in Spanish and English). 16 (2): 1–19.
Allen, Greg (2023-03-14). "In Florida, an invasive snail is helping save an endangered bird". NPR. NPR. Retrieved 2023-03-19.
"Everglade snail kite (Rostrhamus sociabilis plumbeus)". Environmental Conservation Online System. US Fish & Wildlife Service. Retrieved 2023-03-19.
"Rostrhamus sociabilis (Everglade kite)".
Ferguson-Lees, J. & Christie, D. A. & Franklin, K. & Mead, D. & Burton, P. (2001). Raptors of the World. Helm Identification Guides.
"Snail Kite | the Peregrine Fund".
Davis, Steven M.; Ogden, John C. (1994). Everglades: The Ecosystem and its Restoration. CRC Press. p. 508. ISBN 978-0-9634030-2-5.
Pogatchnik, Shawn (12 June 2007). "Bird watcher spots snail kite in S.C." News Room Media. Associated Press. Archived from the original on 23 May 2007. Retrieved 30 July 2009.
"Everglade Snail Kite discovered near Rimini, SC". Cape Romain Bird Observatory. Retrieved 30 July 2009.
Cattau; et al. (27 Nov 2017). "Rapid morphological change of a top predator with the invasion of a novel prey". Nature Ecology & Evolution. 2 (1): 108–115. doi:10.1038/s41559-017-0378-1. PMID 29180705. S2CID 20394037 – via Nature.
Poli; et al. (22 Jun 2022). "An invasive prey provides long-lasting silver spoon effects for an endangered predator". Royal Society. 289 (1977). doi:10.1098/rspb.2022.0820. PMC 9233927. PMID 35730154. S2CID 249891466.