Snail kite

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Snail kite
Schneckenweih-Snail-Kite.JPG
Adult male
Snail kite (Rostrhamus sociabilis) female.jpg
Adult female, Panama
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Aves
Order: Accipitriformes
Family: Accipitridae
Genus: Rostrhamus
Lesson, 1830
Species:
R. sociabilis
Binomial name
Rostrhamus sociabilis
(Vieillot, 1817)
Subspecies [2]
  • R. s. plumbeus - Ridgway, 1874
  • R. s. levis - Friedmann, 1933
  • R. s. major - Nelson & Goldman, 1933
  • R. s. sociabilis - (Vieillot, 1817)
Rostrhamus sociabilis.png
Range of R. sociabilis
  All-year resident
  Breeding only range
  Area of breeding and vagrancy

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.

Contents

Description

Juvenile Rostrhamus sociabilis 110977267 cropped.jpg
Juvenile

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. Adult male, Florida.jpg
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]

Related Research Articles

<span class="mw-page-title-main">Accipitridae</span> Family of birds of prey

The Accipitridae is one of the three families within the order Accipitriformes, and is a family of small to large birds of prey with strongly hooked bills and variable morphology based on diet. They feed on a range of prey items from insects to medium-sized mammals, with a number feeding on carrion and a few feeding on fruit. The Accipitridae have a cosmopolitan distribution, being found on all the world's continents and a number of oceanic island groups. Some species are migratory. The family contains 255 species which are divided into 70 genera.

<span class="mw-page-title-main">Everglades National Park</span> National park in Florida (US)

Everglades National Park is an American national park that protects the southern twenty percent of the original Everglades in Florida. The park is the largest tropical wilderness in the United States and the largest wilderness of any kind east of the Mississippi River. An average of one million people visit the park each year. Everglades is the third-largest national park in the contiguous United States after Death Valley and Yellowstone. UNESCO declared the Everglades & Dry Tortugas Biosphere Reserve in 1976 and listed the park as a World Heritage Site in 1979, and the Ramsar Convention included the park on its list of Wetlands of International Importance in 1987. Everglades is one of only three locations in the world to appear on all three lists.

<span class="mw-page-title-main">Kite (bird)</span> Bird of prey

Kite is the common name for certain birds of prey in the family Accipitridae, particularly in subfamilies Milvinae, Elaninae, and Perninae. The term is derived from Old English cȳta, from the Proto-Indo-European root *gū- , "screech."

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<span class="mw-page-title-main">Lizard buzzard</span> Species of bird

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<span class="mw-page-title-main">Slender-billed kite</span> Species of bird

The slender-billed kite is a South American bird of prey in the family Accipitridae. It is found along a scattered range in forested parts of tropical northern and central South America, and far eastern Panama. The species was recategorized into and has once again been removed from the genus Rostrhamus.

<span class="mw-page-title-main">Hook-billed kite</span> Species of bird

The hook-billed kite, is a bird of prey in the family Accipitridae, which also includes many other diurnal raptors such as kites, eagles, and harriers. It occurs in the Americas, including the Rio Grande Valley of Texas in the United States, Mexico, the Caribbean, Central America, and tropical South America.

<span class="mw-page-title-main">Square-tailed kite</span> Species of bird

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<span class="mw-page-title-main">Letter-winged kite</span> Raptor native to Australia

The letter-winged kite is a small, rare and irruptive bird of prey that is found only in Australia. Measuring around 35 cm (14 in) in length with a wingspan of 84–100 cm (33–39 in), the adult letter-winged kite has predominantly pale grey and white plumage and prominent black rings around its red eyes. Its name derives from its highly distinctive black underwing pattern of a shallow 'M' or 'W' shape, visible when in flight. This distinguishes it from the otherwise similar black-shouldered kite. This species is also the only nocturnal species within the order Accipitriformes despite few differences found in its visual anatomy to other closely related kites.

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Pomacea maculata is a species of large freshwater snail with an operculum, an aquatic gastropod mollusk in the family Ampullariidae, the apple snails.

References

  1. 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.
  2. Gill F, D Donsker & P Rasmussen (Eds). 2020. IOC World Bird List (v10.2). doi : 10.14344/IOC.ML.10.2.
  3. "Snail Kite". All About Birds. Cornell Lab of Ornithology.
  4. 1 2 Ferguson-Lees, J.; Christie, David A. (2001). Raptors of the world: Snail Kite. Houghton Mifflin. pp. 363–365. ISBN   978-0618127627.
  5. "All About Snail Kites". Sharp-Eatman Nature Photography. Retrieved 26 January 2021.
  6. 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.
  7. "Lake Okeechobee Low Lake Stage Restoration Projects". Archived from the original on 4 June 2010.
  8. 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.
  9. 1 2 Allen, Greg (2023-03-14). "In Florida, an invasive snail is helping save an endangered bird". NPR . NPR. Retrieved 2023-03-19.
  10. "Everglade snail kite (Rostrhamus sociabilis plumbeus)". Environmental Conservation Online System. US Fish & Wildlife Service. Retrieved 2023-03-19.
  11. 1 2 "Rostrhamus sociabilis (Everglade kite)".
  12. 1 2 Ferguson-Lees, J. & Christie, D. A. & Franklin, K. & Mead, D. & Burton, P. (2001). Raptors of the World. Helm Identification Guides.
  13. "Snail Kite | the Peregrine Fund".
  14. Davis, Steven M.; Ogden, John C. (1994). Everglades: The Ecosystem and its Restoration. CRC Press. p. 508. ISBN   978-0-9634030-2-5.
  15. 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.
  16. "Everglade Snail Kite discovered near Rimini, SC". Cape Romain Bird Observatory. Retrieved 30 July 2009.
  17. 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.
  18. 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.