Snail kite
{{short description|Species of bird}}
{{Speciesbox
| name = Snail kite
| image = Schneckenweih-Snail-Kite.JPG
| image_caption = Adult male
| image2 = Snail kite (Rostrhamus sociabilis) female.jpg
| image2_caption = Adult female, Panama
| status = LC
| status_system = IUCN3.1
| display_parents = 2
| genus = Rostrhamus
| parent_authority = Lesson, 1830
| species = sociabilis
| authority = (Vieillot, 1817)
| subdivision_ranks = Subspecies
| subdivision_ref = Gill F, D Donsker & P Rasmussen (Eds). 2020. IOC World Bird List (v10.2). doi : 10.14344/IOC.ML.10.2.
| subdivision =
- R. s. plumbeus - Ridgway, 1874
- R. s. levis - Friedmann, 1933
- R. s. major - Nelson & Goldman, 1933
- R. s. sociabilis - (Vieillot, 1817)
| range_map = Rostrhamus sociabilis.png
| range_map_caption = Range of R. sociabilis {{leftlegend|#339966|All-year resident|outline=gray}}{{leftlegend|#99CC00|Breeding only range|outline=gray}}{{leftlegend|#FFEA93|Area of breeding and vagrancy|outline=gray}}
}}
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
File:Rostrhamus sociabilis 110977267 cropped.jpgFile:Female Snail Kite 0168 2.jpgFile:Male Snail Kite 0235.jpg
Snail kites are {{convert|36|to|48|cm|in|abbr=on}} long with a {{convert|99|-|120|cm|in|abbr=on}} wingspan. They weigh from {{convert|300|to|570|g|oz|abbr=on}}. 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 {{convert|29|-|33|cm|in|abbr=on}} each. Its tail is long, at {{convert|16|-|21|cm|in|abbr=on}}, with a white rump and undertail coverts. The dark, deeply hooked beak, measuring {{convert|2.9|-|4|cm|in|abbr=on}} is an adaptation to its diet. The tarsus is relatively long as well, measuring {{convert|3.6|-|5.7|cm|in|abbr=on}}.
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.{{cite web |title=All About Snail Kites |url=https://www.florida-ecology.com/all-about-snail-kites |website=Sharp-Eatman Nature Photography |access-date=26 January 2021 |language=en}}
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.
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
Conservation
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. 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.
=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{{cite web |url=https://www.npr.org/2023/03/14/1157862843/endangered-snail-kite-invasive-apple-snail-florida |title=In Florida, an invasive snail is helping save an endangered bird |last=Allen |first=Greg |date=2023-03-14 |website=NPR |publisher=NPR |language=en |access-date=2023-03-19}} on 11 March 1967.{{cite web |url=https://ecos.fws.gov/ecp/species/7713 |title=Everglade snail kite (Rostrhamus sociabilis plumbeus) |author= |date= |website=Environmental Conservation Online System |publisher=US Fish & Wildlife Service |language=en |access-date=2023-03-19}} The snail kite continued to decline, reaching a population of less than 800 in 2007. One factor for the decline in the 2000s was the introduction of the invasive South American snail Pomacea maculata, which were five times bigger than the native Pomacea paludosa species, and most kites could not eat the new snails.{{Cite news |url=https://www.pbs.org/wnet/nature/this-bird-is-evolving-right-in-front-of-us/30077/ |title=This Bird Is Evolving Right in Front of Us |access-date=2025-05-12 |newspaper=Nature The WNET Group }} However, the kites quickly evolved to be 12% bigger to adapt to the new food source.{{Cite news |url=https://az.pbslearningmedia.org/resource/snail-kites-evolve-to-make-comeback-video/nature-season-42-raptors-a-fistful-of-daggers/ |title=Snail Kites Evolve to Make Surprising Comeback |access-date=2025-05-12 |newspaper=Nature PBS }}{{cite web |url=https://wildlife.org/invasive-snails-rescue-endangered-bird-of-prey/ |title=Invasive snails rescue endangered bird of prey |date=October 11, 2016 |author=Nala Rogers |publisher=The Wildlife Society }} This population gradually rebounded, 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.
Diet
File:Snail Kite, Chagres lake, Panama imported from iNaturalist photo 31341912.jpg
This is a gregarious bird of freshwater wetlands, forming large winter roosts. Its diet consists almost exclusively of apple snails, especially the species Pomacea diffusa, P. maculata and P. paludosa in Florida, other species of Pomacea (P. doliodes) elsewhere in its range, and species of the genus Marisa (M. cornuarietis).{{Cite web|url=https://animaldiversity.org/accounts/Rostrhamus_sociabilis/|title = Rostrhamus sociabilis (Everglade kite)| website=Animal Diversity Web }}Ferguson-Lees, J. & Christie, D. A. & Franklin, K. & Mead, D. & Burton, P. (2001). Raptors of the World. Helm Identification Guides.Reichert, B. E., Cattau, C. E., Fletcher, J. R. J., W, S. J. P., A, R. J. J., & Bennetts, R. E. (2020). Snail Kite (Rostrhamus sociabilis), version 1.0. birdsoftheworld.org. https://doi.org/10.2173/bow.snakit.01
Snail kites have been observed eating other prey items in Florida, including other freshwater snail species (such as the banded mystery snail), crayfish in the genus Procambarus, crabs in the genera Dilocarcinus and Poppiana (P. dentata), black crappie, ring-necked snakes, small turtles (including the common musk turtle, striped mud turtle, coastal plain cooter, Florida red-bellied cooter, Florida softshell turtle, and other unidentified species), rodents and carcasses (based only on a single reported case of a dead American coot).{{cite web | url=https://www.peregrinefund.org/explore-raptors-species/kites/snail-kite | title=Snail Kite | the Peregrine Fund }}Reichert, B. E., Cattau, C. E., Fletcher, J. R. J., W, S. J. P., A, R. J. J., & Bennetts, R. E. (2020). Snail Kite (Rostrhamus sociabilis), version 1.0. birdsoftheworld.org. https://doi.org/10.2173/bow.snakit.01 It is believed that snail kites turn to these alternatives only when apple snails become scarce, such as during drought, 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.
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.{{Cite journal |last=Cattau |display-authors=etal |date=27 Nov 2017 |title=Rapid morphological change of a top predator with the invasion of a novel prey |url=https://www.nature.com/articles/s41559-017-0378-1 |journal=Nature Ecology & Evolution |volume=2 |issue=1 |pages=108–115 |doi=10.1038/s41559-017-0378-1 |pmid=29180705 |s2cid=20394037 |via=Nature|url-access=subscription }} These non-native snails provide a better food source than the smaller native snails and have had a positive effect on the kites' populations.{{Cite journal |last=Poli |display-authors=etal |date=22 Jun 2022 |title=An invasive prey provides long-lasting silver spoon effects for an endangered predator |journal= Proceedings of the Royal Society B: Biological Sciences|volume=289 |issue=1977 |doi=10.1098/rspb.2022.0820 |pmid=35730154 |pmc=9233927 |s2cid=249891466 |doi-access=free |bibcode=2022RSPSB.28920820P }}
References
External links
- {{Commons category-inline|Rostrhamus sociabilis}}
- {{Wikispecies inline|Rostrhamus sociabilis}}
- [https://web.archive.org/web/20120712181212/http://floridabirdingtrail.com/index.php/conservation/bird/snail_kite Snail Kite Information] at [https://web.archive.org/web/20120623094553/http://floridabirdingtrail.com/index.php Great Florida Birding & Wildlife Trail]
- {{BirdLife|22695048|Rostrhamus sociabilis}}
- {{Avibase|name=Rostrhamus sociabilis}}
- {{InternetBirdCollection|snail-kite-rostrhamus-sociabilis|Snail kite}}
- {{VIREO|Snail+kite}}
- {{IUCN_Map|22695048/168999707|Rostrhamus sociabilis}}
- {{Xeno-canto species|Rostrhamus|sociabilis|Snail kite}}
{{Accipitrimorphae|A.|state=collapsed}}
{{Taxonbar|from=Q839657}}
Category:Birds described in 1817
Category:Birds of South America
Category:Birds of the Yucatán Peninsula