{{Short description|Genus of birds}} {{Use British English|date=March 2024}} {{Automatic taxobox | fossil_range = Late Holocene | image = Kagu Rhynchetos jubatus detail.JPG | image_caption = ''Rhynochetos jubatus'' | taxon = Rhynochetos | authority = Verreaux & Des Murs, 1860 | synonyms = | subdivision_ranks = Species | subdivision = See text }}
'''''Rhynochetos''''' is a genus of ground-dwelling<ref name="Warner-1948">{{Cite journal|last=Warner|first=Dwain Willard|date=1948|title=The Present Status of the Kagu, ''Rhynochetos jubatus'', on New Caledonia|journal=The Auk|volume=65|issue=2|pages=287–288|doi=10.2307/4080305|jstor=4080305|doi-access=free}}</ref> birds in the monotypic family '''Rhynochetidae'''. It contains two species, both endemic to New Caledonia, one of which is extinct.<ref name=balouet>{{cite journal |author1=Balouet, J.C. |author-link=Jean Christophe Balouet |author2=Olson, Storrs L. |author2-link=Storrs Olson |year=1989 |title=Fossil birds from Late Quaternary deposits in New Caledonia |journal=Smithsonian Contributions to Zoology |volume=469 |issue=469 |pages=28–32 |url=http://si-pddr.si.edu/dspace/bitstream/10088/5164/2/SCtZ-0469-Lo_res.pdf |doi=10.5479/si.00810282.469 |archive-date=2012-08-15 |access-date=2013-08-02 |archive-url=https://web.archive.org/web/20120815041832/http://si-pddr.si.edu/dspace/bitstream/10088/5164/2/SCtZ-0469-Lo_res.pdf |url-status=dead }}</ref>
== Taxonomy == ''Rhynochetos jubatus'' is the only extant species of this genus and of the family Rhynochetidae. It is closely related to birds of the tropical Atlantic, Pacific and Indian oceans with its closest living relative being the sunbittern (''Eurypyga helias'').<ref name="Hunt-1997">{{Cite thesis|last=Hunt|first=Gavin Raymond|title=Ecology and conservation of the kagu ''Rhynochetos jubatus'' of New Caledonia: a thesis presented in partial fulfilment of the requirements for the degree Doctor of Philosophy in Ecology at Massey University|date=1997|publisher=Massey University|hdl=10179/2703}}</ref> Currently there are two described species of ''Rhynochetos'', however, it has been suggested that the extinct ''Rhynochetos orarius'' and the extant ''Rhynochetos jubatus'' are the same species.<ref>{{Cite journal|last1=Theuerkauf|first1=Jörn|last2=Gula|first2=Roman|date=February 2018|title=Indirect evidence for body size reduction in a flightless island bird after human colonisation|journal=Journal of Ornithology|volume=159|issue=3|pages=823–826|doi=10.1007/s10336-018-1545-0|issn=2193-7192|doi-access=free|bibcode=2018JOrni.159..823T }}</ref>
== Species ==
* ''Rhynochetos jubatus'' <small>Verreaux & Des Murs, 1860</small> – kagu * †''Rhynochetos orarius'' <small>Balouet & Olson, 1989</small> – lowland kagu
== Description == Kagus are large, flightless birds described as something "between a small heron and a rail".<ref name="Hunt-1996">{{Cite journal|last=Hunt|first=Gavin R.|date=October 1996|title=Environmental variables associated with population patterns of the Kagu ''Rhynochetos jubatus'' of New Caledonia|journal=Ibis|volume=138|issue=4|pages=778–785|doi=10.1111/j.1474-919x.1996.tb08836.x|issn=0019-1019}}</ref> Adults are about {{convert|55|cm}} tall with uniform ash-grey plumage with distinct orange-red bills and legs.<ref name="iucn">{{cite iucn |author=BirdLife International |year=2019 |title=''Rhynochetos jubatus'' |article-number=e.T22692211A156666402 |doi=10.2305/IUCN.UK.2019-3.RLTS.T22692211A156666402.en}}</ref> Characteristic of these birds are long crest feathers. They weigh between {{convert|700|and|1000|g}}, with no significant size difference between males and females.<ref>{{Cite web |last=EuroKids |date=2025-01-10 |title=List of Animals that Live Both on Land and Water |url=https://www.eurokidsindia.com/blog/list-of-animals-that-live-on-land-and-water.php |access-date=2025-06-30 |website=EuroKids |language=en-GB}}</ref>
Herons can look anatomically similar but can be distinguished by the lack of bare red parts and uniform grey plumage.<ref name="iucn" />
== Habitat and distribution == Kagus are endemic to the small islands of New Caledonia in the South Pacific, measuring 8,000 square miles.<ref name="Warner-1948" /> They inhabit remote, dense tropical forest regions in valleys of the southern mountainous region, as well as tall shrublands in lesser numbers. They tend to avoid shallow shrublands and savannah-grassland habitats.<ref name="Hunt-1996" /> Typically, they require a dense canopy layer as well as a thick litter layer in which they forage for food.<ref>{{Cite journal|last1=Theuerkauf|first1=Jörn|last2=Haneda|first2=Tokushi|last3=Okahisa|first3=Yuji|last4=Sato|first4=Nozomu J.|last5=Rouys|first5=Sophie|last6=Bloc|first6=Henri|last7=Ueda|first7=Keisuke|last8=Watanabe|first8=Izumi|last9=Kuehn|first9=Ralph|date=April–May 2017|title=Elevated concentrations of naturally occurring heavy metals inversely correlate with reproductive output and body mass of the Kagu ''Rhynochetos jubatus''|journal=Ibis|volume=159|issue=3|pages=580–587|doi=10.1111/ibi.12474|issn=0019-1019}}</ref>
The distribution of kagus over the island is very fragmented due to a very patchy forest cover. The forests lie of ultrabasic rocks, which tend to have less extensive forest cover. On these rocks, forests are restricted to higher altitudes and along water systems. Dry season fires also contribute to decreasing forest cover and thus further fragmentation of kagu populations.<ref name="Hunt-1996" />
== Behaviour ==
=== Vocalizations === Kagus have distinct sex-specific songs which they sing in the early morning.<ref name="Hunt-1996" /> These songs can carry for distances of up to 2 km. Mating pairs will often sing duets in the early morning, which may be territorial behaviour. Males tend to sing more frequently than females, and solitary songs tend to belong to males more often than females.
Kagu calls have been described as strange. They have various quiet hissing sounds and rattling calls.<ref name="Hunt-1996" />
=== Diet === Kagus forage most of the day for food in the litter layer and in low parts of trees and trunks.<ref name="Hunt-1997" /> They are generalists, eating a wide variety of prey, from invertebrates such as earthworms, beetles and snails to lizards and small fish. Their food supply is influenced by seasonality, eating larger prey when there is more food availability, such as in wetter seasons. In drier seasons, kagus will eat smaller prey such as larvae. In wetter seasons, when food is more available, they will spend less of the day foraging and carry out other activities, such as preening.<ref name="Hunt-1997" />
=== Reproduction === Kagu pairs nest in large permanent territories.<ref name="Hunt-1996" /> Outside of breeding the male and the female will live separately within their shared territory. There is no well-defined breeding season, however, pairs tend to have more breeding attempts during wetter periods. Some young may remain in their parent's territory for several years, even helping in rearing younger siblings.<ref>{{Cite journal|last1=Letocart|first1=Yves|last2=Salas|first2=Michel|date=June 1997|title=Spatial Organisation and Breeding of Kagu ''Rhynochetos jubatus'' in Rivière Bleue Park, New Caledonia|journal=Emu |volume=97|issue=2|pages=97–107|doi=10.1071/mu97013|bibcode=1997EmuAO..97...97L |issn=0158-4197}}</ref>
Kagus raise on average about one hatchling yearly. The amount of breeding attempts of kagus are very variable, with any from 0-7 breeding attempts per year possible until a successful breeding attempt takes place. They will lay and incubate a single egg for about 5 weeks. At 3 days old, the parents will feed the chick during the day and brood at night. This will occur for 2 months, at the end of which the fledgling will be two thirds of its adult body size. The fledgling will typically be fed until it reaches 3.5 to 4 months of age.<ref name="Hunt-1997" /> Kagus have long lifespans, with many living 20 to 30 years in captivity.<ref name="Warner-1948" />
== Threats to conservation == Prior to the discovery of the island by Captain James Cook in 1774, there was a healthy population of both species of ''Rhynochetos''. Following the discovery of the island, various human activities threatened the stability of kagu populations. The kagus began being trapped heavily, both for its meat and for its export. The beautiful display of the male led to its export around the world to zoos and museums. Introduced domestic animals, such as cats and dogs are a major threat to the kagus. They roam free around the island and eat adults, juveniles and eggs. Other human activity, such as logging and hunting has further fragmented their habitat.<ref name="Warner-1948" /> These birds tend to avoid human settlements; areas with increased human activity tend to have lower numbers. Maintenance of genetic diversity of the kagus is therefore threatened as further fragmentation is further isolating patches and may decrease migration between the patches.<ref name="Hunt-1996" />
==References== {{Reflist}}
== External links == * [http://www.oiseaux.net/birds/kagu.html Oiseaux] * [http://datazone.birdlife.org/species/factsheet/22692211 Bird Life International] * [https://www.hbw.com/species/kagu-rhynochetos-jubatus Handbook of the Birds of the World] * [https://avibase.bsc-eoc.org/species.jsp?avibaseid=227D77FBFA6E408A&avibaseid=227D77FBFA6E408A Avibase] *{{cite iucn |author=BirdLife International |date=2019 |title=''Rhynochetos jubatus'' |volume=2019 |article-number=e.T22692211A156666402 |doi=10.2305/IUCN.UK.2019-3.RLTS.T22692211A156666402.en |access-date=12 November 2021}}
{{Eurypygimorphae|E.|state=collapsed}} {{Taxonbar|from=Q2639899}}
Category:Bird genera Category:Bird genera with one living species Category:Endemic birds of New Caledonia