Burhinus is a genus of birds in the family Burhinidae. This family also contains the genera Esacus and Hesperoburhinus.del Hoyo J, Elliott A, Sargatal J (1996) Handbook of the Birds of the World, vol 3. Lynx, Barcelona The genus name Burhinus comes from the Greek bous, ox, and rhis, nose.
The species of Burhinus are commonly called stone-curlew, thick-knee, or dikkop. They are medium-sized, terrestrial waders, though they are generally found in semi-arid to arid, open areas. Only some species of Burhinus are associated with water. The genus ranges from 32 cm to 59 cm in size. Burhinus are characterised by their long legs, long wings and cryptic plumage. Most species have a short, thick, strong bill,Marchant, S., & P.J. Higgins (eds) 1993. Handbook of Australian, New Zealand and Antarctic Birds. Volume 2: Raptors to Lapwings. Oxford University Press, Melbourne. to which the generic name alludes. The stone-curlews are found all over the world except Antarctica. They are mainly tropical, with the greatest diversity in the Old World.
Taxonomy and systematics
The genus Burhinus was erected by the German zoologist Johann Karl Wilhelm Illiger in 1811 with the bush stone-curlew as the type species. The name combines the Ancient Greek bous meaning "ox" and rhis, rhinos meaning "nose" (or "bill").
Determining the correct placement of this family can be difficult as they are very ancient species.Ericson PGP, Christidis L, Cooper A, Irestedt M, Jackson J, Johansson US and Norman JA: A Gondwanan origin of passerine birds supported by DNA sequences of the endemic New Zealand wrens. Proceedings of the Royal Society of London Ser B 2002, 269:235-241van Tuinen M, Sibley CG and Hedges SB: The early history of modern birds inferred from DNA sequences of nuclear and mitochondrial ribosomal genes. Molecular Biology and Evolution 2000, 17:451-457.García-Moreno J and Mindell DP: Rooting a phylogeny with homologous genes on opposite sex chromosomes (gametologs): a case study using avian CHD. Molecular Biology and Evolution 2000, 17:1826-1832. Burhinus are best placed in Charadriiformes. They resemble bustards (family: Otididae) and have been previously classified with them in Gruiformes. Their placement in Gruiformes is considered convergent evolution, as both orders have the same lifestyle and biotopes. Comparisons made of skeleton, biochemistry and parasites plus down on young, confirm Burhinus as a charadriiform.
Based on multi-locus analysis, the stone-curlew family (Burhinidae) is probably closest to the family Charadriidae, not Scolopacidae. The optimal maximum likelihood phylogenetic reconstruction using multi-locus (ADH5, GPD3-5 and FGB-7) analysis placed Burhinus within Charadrii, sister to Scolopaci.Fain MG and Houde P (2007) Multilocus perspectives on the monophyly and phylogeny of the order Charadriiformes (Aves). BMC Evolutionary Biology 7:35. They have some similarities to Glareolidae and some phylogenies do place them as a sister clade to this family.Chu PC (1995) Phylogenetic reanalysis of Strauch’s osteological data set for the Charadriiformes. The Condor 97:174–196Strauch J (1978) The phylogeny of the Charadriiformes (Aves): a new estimate using the method of character compatibility analysis. Trans Zool Soc Lond 34:263–345Mayr G (2011) The phylogeny of charadriiform birds (shorebirds and allies)––reassessing the conflict between morphology and molecules. Zool J Linn Soc 161:916–934 however this is also considered convergent evolution. DNA–DNA hybridisation as well as RAG-1 and myoglobin intron-II sequence data supports a link to Recurvirostridae.Sibley CG & Ahlquist JE (1990) Phylogeny and classification of birds. Yale University Press, New Haven, Conn.Ericson PGP, Envall I, Irested M and Norman JA (2003) Inter-familial relationships of the shorebirds (Aves: Charadriiformes) based on nuclear DNA sequence data. BMC Evolutionary Biology 3:16. Burhinus and Chionis together are sister to the rest of the Charadriidae.Paton TA, Baker AJ, Groth JG, Barrowclough GF (2003) RAG-1 sequences resolve phylogenetic relationships within charadriiform birds. Mol Phylogen Evol 29:268–278Paton TA, Baker AJ (2006) Sequences from 14 mitochondrial genes provide a well-supported phylogeny of the charadriiform birds congruent with the nuclear RAG-1 tree. Mol Phylogen Evol 39:657–667Baker AJ, Pereira SL, Paton TA (2007) Phylogenetic relationships and divergence times of Charadriiformes genera: multigene evidence for the Cretaceous origin of at least 14 clades of shorebirds. Biol Lett 3:205–209
A phenotypic study of Charadriiformes suggests that Burhinidae should consist of three genera – Esacus, Burhinus plus resurrected Orthorhampus. In this model, the bush stone-curlew would be removed from Burhinus and placed in a subfamily Esacinae with Esacus. This subfamily would be known as the greater thick-knees, while the remainder of the genus Burhinus would fall into Burhininae, the lesser thick-knees. This is based on character analyses of skeletons, skin and natal patterns.Livezey BC (2009) Phylogenetics of modern shorebirds (Charadriiformes) based on phenotypic evidence: analysis and discussion. Zool Jour Linn Soc 160:567–618. Esacus has sometimes been lumped within Burhinus, but Esacus are generally larger and chunkier with a larger bill and less mottled plumage. Burhinus is clearly distinct from Esacus, except for the bush stone-curlew, which is the same size as Esacus. However, the bush stone-curlew has more similar plumage to the rest of Burhinus. The Indian stone-curlew was split from the Eurasian species, as it does not migrate.Sharma M, Sharma RK (2015) Ecology and Breeding Biology of Indian Stone Curlew (Burhinus indicus). Nat. Env. & Poll. Tech. 14(2):423-426 It is possible that the population of Eurasian stone-curlews on the Canary Islands should also be split in this way as this population shows very little genetic variation.Mori A, Baldaccini NE, Baratti M, Caccamo C, Dessì-Fulgheri F, Grasso R, Nouira S, Ouni R, Pollonara E, Rodriguez-Godoy F, Spena MT, Giunchi D (2014) A first assessment of genetic variability in the Eurasian Stone-curlew Burhinus oedicnemus. Ibis 156(3):687-692. In IOC 14.1, the double-striped thick-knees were transferred to the newly described genus Hesperoburhinus.
The bush stone-curlew has had a confusing history of classification. This species has previously been considered two species and B. magnirostris has at times been used for this species, with the same specific epithet now used for the beach stone-curlew in the sister genus Esacus, leading to much confusion. The Bush stone-curlew is now B. grallarius, as described by John Gould in 1845.
Species There are six species of Burhinus. No species is threatened and none have become extinct since 1600.
Picture Name Binomial name Distribution Eurasian stone-curlew Burhinus oedicnemusEurope, north Africa and southwestern Asia. Indian stone-curlew Burhinus indicus South and South-eastern Asia Senegal thick-knee Burhinus senegalensisAfrica between the Sahara and the equator Water thick-knee Burhinus vermiculatusAngola, Botswana, Burkina Faso, Burundi, Cameroon, Central African Republic, Republic of the Congo, Democratic Republic of the Congo, Ivory Coast, Eswatini, Ethiopia, Gabon, Ghana, Kenya, Liberia, Malawi, Mozambique, Namibia, Niger, Nigeria, Rwanda, Senegal, Somalia, South Africa, Tanzania, Uganda, Zambia, and Zimbabwe. Spotted thick-knee Burhinus capensiscentral and southern Africa. Bush stone-curlew Burhinus grallarius (formerly B. magnirostris) Australia.
There are three fossil species known:
Burhinus lucorum Bickart, 1981 from the Early Miocene of Nebraska Burhinus aquilonaris Feduccia, 1980 from the Pleistocene of Kansas Dwarf thick-knee, Burhinus nanus Brodkorb, 1959 from the Late Pleistocene of The Bahamas
Description Burhinus are a genus of long-legged, large-eyed, terrestrial waders with eerie nocturnal calls. They range from 32 cm (Senegal thick-knee) to 59 cm (bush stone-curlew). There are generally only minor plumage differences between the sexes, and the late juveniles of Burhinus appear similar to the adults. Females may be smaller. All species of this genus have cryptic plumage of sandy browns with streaks and mottles, usually with spots of cream, buff, brown and black. The head of the Burhinus has a broad domed crown, giving rise to the Afrikaans name of dikkop, which translates to "thick head". The closed wings of most Burhinus have banded upper coverts. This is not as prominent on the Hesperoburhinus species; the Peruvian thick-knee is plainer and greyer except for the head. In flight, Burhinus’ wing plumage is much more striking with patterning that contrasts with the otherwise cryptic plumage. All Burhinus have black primary feathers with white patches, which is most developed in Bush stone-curlews. The wings are long and are held straight and out stretched in flight. Burhinus have a marked carpal angle and the outer wing has minimal tapering, with a pointed tip in some species. The inner wing is thinner, with 16-20 secondary feathers. Burhinus have 11 primary feathers, of which the outer most is very small and covered by the primary coverts. The twelve tail feather are generally short and rounded, except in the Spotted thick-knee which is medium in length and the Bush stone-curlew which has a longer more tapered tail. Their legs often extend beyond the tail in flight.
Typically, the Burhinus bill is stout, and is considered medium to short in length for a wader. The tip of the bill is bulbous with sharp point when viewed from side, while from the top view it has a broad base. The bill is mostly dark but can have yellow at the base, with slit-like perforated nostrils like Laridae.
The long legs of Burhinus range from pale ochre to vivid yellow in colour. The tibia is exposed and the swollen tibiotarsal (‘knee’ joint – actually ankle) is where name ’thick-knee’ came from. Their legs are markedly scaled and only have three slight webbed, forward facing toes with no hind toe. Burhinus move on the land with a measured sedate walk; head and body held horizontal in the same position to when they lay on the ground. The long strides easily move from walk to run with head held forward. Flight can quickly follow and their flight is fast and direct with little maneuverability. Burhinus will generally run before they take off and run for a short distance on landing. Their active flight consists of regular, shallow wing beats similar to Numenitus.
All Burhinus have a complete post-breeding moult which can take 4–5 months. The primaries are lost in descending sequence. The Eurasian and Senegal thick-knees may suspend moulting of primaries in winter and finish in spring, leading to an overlap of moulting and breeding. It is very unusual for breeding and moulting to overlap, and the slow moult may possibly be to maximise re-nesting potential.Giunchi D, Caccamo C & Pollonara E (2008) Pattern of Wing Moult and Its Relationship to Breeding in the Eurasian Stone-Curlew Burhinus oedicnemus. Ardea, 96(2):251-260. Burhinus’ secondary feathers are usually not replaced in one season, with the inner and outer feather being shed first.Giunchi D, Chiara C, Mori A, Fox JW, Rodrıguez-Godoy F, Baldaccini NE, Pollonara E (2015) Pattern of non-breeding movements by Stone-curlews Burhinus oedicnemusbreeding in Northern Italy. J Ornithol 156:991–998 A pre-breeding moult may just be the head and neck and sometimes not at all. Once they have fledged, juvenile Burhinus will moult only their head and body, some wing-coverts and central tail. Juveniles will moult their secondary wing feathers after their first winter. This can be helpful when estimating the age of young birds.
Distribution and habitat