St. Croix macaw
| St. Croix macaw Temporal range: LateHolocene
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|---|---|
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| Holotypelefttibiotarsusin two views | |
Scientific classification
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| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Psittaciformes |
| Family: | Psittacidae |
| Genus: | Ara |
| Species: | †A. autocthones
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| Binomial name | |
| †Ara autocthones Wetmore,1937
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| Red arrows indicate locations onPuerto RicoandSt. Croixwhere remains of this macaw have been found | |
| Synonyms | |
TheSt. Croix macaw(Ara autocthones) orPuerto Rican macawis anextinctspecies ofmacawwhose remains have been found on theCaribbean islandsofSt. CroixandPuerto Rico.It was described in 1937 based on atibiotarsusleg bone unearthed from akitchen middenat apre-Columbiansite on St. Croix. A second specimen consisting of various bones from a similar site on Puerto Rico was described in 2008, while acoracoidfromMontserratmay belong to this or another extinct species of macaw. The St. Croix macaw is one of 13 extinct macaw species that have been proposed to have lived on the Caribbean islands. Macaws were frequently transported long distances by humans in prehistoric and historical times, so it is impossible to know whether species known only from bones or accounts were native or imported.
As it is only known from bones, the St. Croix macaw's color is not known. Extant macaws can generally be grouped in either large-body or small-body size clusters. Yet, the bones of the St. Croix macaw are intermediate in size between the two, and it was slightly larger than the extinctCuban macaw(Ara tricolor). Only theblue-throated macaw(Ara glaucogularis) andLear's macaw(Anodorhynchus leari) are similar in size. It differed from other macaws in various skeletal details and shared several features with only the genusAra.Like other macaw species in the Caribbean, the St. Croix macaw is believed to have been driven to extinction by humans, as indicated by the fact that its remains were found in kitchen middens.
Taxonomy
[edit]In 1934, the archeologist Lewis J. Korn (working under theMuseum of the American Indian) excavated akitchen midden(a dump for domestic waste) at a site nearConcordiaon the southwestern coast ofSt. Croix,one of theVirgin Islandsin theCaribbean Sea.The midden was located 370 m (400 yd) inland from the beach, and its depth was around 76 cm (30 in). Bones of mammals, birds, turtles, and fish were obtained from the bottom of the deposit, with bird bones being concentrated at the mid-level. The exact age of the material could not be determined, but since no European origin objects were found in the deposit, it was assumed to bepre-Columbian,between 500 and 800 years old. 23 species of birds were represented among the well-preserved bones, some of which wereextinct.In 1937, the ornithologistAlexander Wetmoreidentified several species among these bones, including a lefttibiotarsus(lower leg bone) of an immaturemacaw,which was unexpected since no such birds were previously known from St. Croix.[1]
Wetmore made the tibiotarsus theholotype specimenof a new macaw species, which he placed in the genusAra,asAra autocthones.Thespecific nameis from theAncient Greekαὐτόχθων(autochthon), meaning native or aborigine. The holotype is housed along with the other bones found at the U.S.National Museum of Natural History,cataloged as USNM 483530. Though numerous other now-extinct macaws had been described from the Caribbean based on old accounts alone, the only other species described based on physical remains at the time was theCuban macaw(Ara tricolor), which was known from skins. Though Wetmore conceded that many uncertainties were surrounding the bone, especially regarding its affinities to other Caribbean macaws, he thought it appropriate to designate it as a new species.[1][2][3]
In 1978, the ornithologistStorrs L. Olson(using the spellingautochthones) agreed that the bone belonged to a macaw not assignable to any known species, but noted it may not have been native to St. Croix, sinceindigenous Caribbeansare known to have kept and traded macaws over long distances.[4]In 1983, he indicated that if the macaw had indeed been transported, the specific name would be amisnomer.[5]The zoologist Elizabeth S. Wing agreed in 1989 that the macaw could have been traded,[6]but the ornithologists Matthew I. Williams and David W. Steadman stated in 2001 that given the evidence for other macaws having existed in the region, there was no reason why St. Croix could not have had an indigenous species.[7]
In 1987, the ornithologist Edgar J. Máiz López found several associated bones of a single bird (cataloged as USNM 44834) at the Hernández Colón archeological site on the eastern bank of theCerrillos-Bucanáriver in south central Puerto Rico. The archeological site represents a pre-ColumbianSaladoid-Ostionoidvillage of around 15,000m2(3.7acres) in size, situated on analluvial terrace.Both cultural and faunal remains were excavated, and the macaw remains were found in a kitchen midden deposit that has been dated to around 300 AD. The specimen consists of partial bones including the leftcoracoid(missing a portion of thebone's "head"), both ends of the lefthumerus,the upper end of the rightradius,the leftcarpometacarpus(missing onemetacarpal), the leftfemur(lacking the lower end), the right tibiotarsus (lacking part of the upper articular surface), upper and lower portions of the left tibiotarsus, as well as unidentified elements. In 2008, Olson and Máiz López assigned the specimen toAra autocthones(it had been assigned toArasp. in 2004, indicating uncertain classification within the genusAra), as its tibiotarsus is identical in size to the holotype.[3][8]
Olson and Máiz López considered it likely thatAra autocthoneswas endemic to theWest Indianregion rather than a species transported from the mainland by Native Americans, as it is far more likely a species restricted to islands would have been driven extinct. Since they found it unlikely the bird occurred naturally on St. Croix and questioned whether it could even have occurred naturally on Puerto Rico, they considered the nameautocthones"probably one of the worst possible choices" for the species. Thoughfossilsof the parrot generaAmazonaandAratingahave been found in pre-human sites on Puerto Rico, none such belonging to macaws have been found. Olson and Máiz López conceded that macaws are unlikely to be found in cave deposits and noted that the Cuban macaw's fossils had been found in aquatic deposits. They also pointed out that various animal species were transported and kept in captivity by Native Americans – for example thePuerto Rican hutia(Isolobodon portoricensis,an extinctrodent) and theAntillean cave rail(Nesotrochis debooyi,an extinct flightless rail) were both transported to St. Croix and found in kitchen middens.[3]
Olson and Máiz López pointed out that a coracoid from the island ofMontserrat(reported by Williams and Steadman in 2001, and cataloged asUF4416) could belong to the macaw of St. Croix and Puerto Rico or the Cuban macaw, as it was within the size range of the two (smaller than the former).[3]The ornithologists James W. Wiley and Guy M. Kirwan instead suggested in 2013 that the bone from Montserrat could belong to the extinctLesser Antillean macaw(A. guadeloupensis) ofGuadeloupe.[9]Ara autocthoneshas been referred to as the St. Croix macaw, but, after more remains were described from Puerto Rico, it has also been called the Puerto Rican macaw.[7][9][10]The ornithologistJoseph M. Forshawargued in 2017 that the latter was a more appropriate name since he found it more plausible that it naturally occurred on Puerto Rico and had been transported to the Virgin Islands.[11]
As many as 13 now-extinct species of macaw have lived on the Caribbean islands, it has been suggested. Still, many of these were based on old descriptions or drawings and represented onlyhypothetical species.[12]In addition to the St. Croix macaw, only two other endemic Caribbean macaw species are known from physical remains; the Cuban macaw is known from 19 museum skins andsubfossils,and the Lesser Antillean macaw is possibly known from subfossils.[3][13]Macaws are known to have been transported between the Caribbean islands and from mainland South America to the Caribbean, both in prehistoric times byPaleoamericansand in historic times by Europeans and natives. Parrots were important in the culture of native Caribbeans and were among the gifts offered to the explorerChristopher Columbuswhen he reached theBahamasin 1492. Historical records of macaws on these islands, therefore, may not have represented distinct, endemic species; it is also possible that these macaws were escaped or feral birds that had been transported to the islands from elsewhere.[3]The identity and distribution of indigenous macaws in the Caribbean are likely to be resolved only through paleontological discoveries and examination of contemporary reports and artwork.[9][14]
Description
[edit]
Since only bones are known of the St. Croix macaw, nothing can be said about its coloration.[10]While the holotype tibiotarsus appears to belong to a fully grown individual, the fact that the bone is slightly spongy at the ends indicates it was immature. This left tibiotarsus is 77.7 mm (3.06 in) in total length, 9.4 mm (0.37 in) in breadth from side to side across the lower end, and the smallest breadth from side to side of the shaft is 3.9 mm (0.15 in). Though similar to the same bone in the Cuban macaw, it is wider from side to side (comparisons between the lower ends of their tibiotarsi indicate it was a slightly larger bird). It is slender compared to those of larger macaws. The holotype tibiotarsus is intermediate in size between those of large macaws such as thescarlet macaw(Ara macao) and themilitary macaw(Ara militaris), and the smallchestnut-fronted macaw(Ara severus). Compared to the tibiotarsi of extant macaws, the bone is more slender and has a slightly greater hindwards development of the upper end. Apart from this, its only distinguishing feature is that its dimensions do not fall within those of other known species. The slender proportions of the bone and more elongated ridges around the upper end show it is a macaw and distinguishes it from the Amazon parrots such as the largeimperial amazon(Amazona imperialis).[1]
The tibiotarsus of the assigned specimen is essentially identical in size to the holotype. It is 74.5 mm (2.93 in) from the upper articular surface, 47.2 mm (1.86 in) from the lower end of the fibular crest to the externalcondyle(the round prominences at the end of a bone), 11.4 mm (0.45 in) deep through the innercnemial crest(a ridge at the front side of the head), 5.2 by 4.0 mm (0.20 by 0.16 in) wide and deep at the mid shaft, and 10.1 mm (0.40 in) wide at the lower end. The estimated length of the coracoid is 43.5 mm (1.71 in) from its head to the internal corner of thesternalfacet, 26.5 mm (1.04 in) from the base of the procoracoid process to the internal corner of the sternal facet, the glenoid facet is 10.5 by 6.1 mm (0.41 by 0.24 in) wide and deep, the shaft is 5.2 by 4.4 mm (0.20 by 0.17 in) wide and deep at midpoint, and the sternal facet is 10.5 mm (0.41 in) wide. The upper width of the humerus is 19.9 mm (0.78 in), the depth through its external tuberosity is 12.8 mm (0.50 in), the depth of its head is 6.2 mm (0.24 in), the width of the lower end is about 15.5 mm (0.61 in), and the height and width of the radial condyle is 7.4 by 5.0 mm (0.29 by 0.20 in). The carpometacarpus is 55.8 mm (2.20 in) long, its upper depth is 14.3 mm (0.56 in), the trochlea (a grooved structure where bones join) is 5.7 mm (0.22 in) wide, and the shaft is 4.5 by 5.0 mm (0.18 by 0.20 in) at midpoint. The upper part of the radius is 6.0 mm (0.24 in) at its greatest diameter. The estimated length of the femur is 51.5 mm (2.03 in), its upper width is 12.5 mm (0.49 in), the depth through itstrochanteris 8.2 mm (0.32 in), the head is 6.2 mm (0.24 in) deep, and the shaft is 4.9 by 5.4 mm (0.19 by 0.21 in) wide and deep at its midpoint.[3]
Olson and Máiz López stated that extant macaws fall into two size-clusters, representing large and small species. In contrast, the St. Croix macaw was distinct in being intermediate between the two clusters, with only theblue-throated macaw(Ara glaucogularis) andLear's macaw(Anodorhynchus leari) being similar in size. They observed that thepectoralattachment on the humerus is less excavated compared to those two macaws. In contrast, the capital groove (a groove separating two parts of the humerus's head) is wider. The head of the femur is more massive, and when seen from the back, is more excavated under the head, neck, and trochanter. In contrast, the femur's more robust shaft is similar to that ofArabut dissimilar toAnodorhynchus.The tibiotarsus is more robust with a flared lower extremity. The tibiotarsus' length is shorter than in the blue-throated macaw but longer than in Lear's macaw. In contrast, the lengths of the coracoid, carpometacarpus, and femur are smaller than in either.[3]
Olson and Máiz López ruled out the specimen from Puerto Rico belonging to the Amazon parrots by pointing out characters found only inAramacaws. The coracoid is more elongated and has a relatively narrow shaft, and the ventral lip of the glenoid facet (equivalent to theglenoid fossaof mammals) protrudes more. The carpometacarpus is proportionally much longer with aprocesson thealular metacarpalthat is not curved at its upper part, while the ectepicondylar process (a bony elevation) and the attachment of pronator brevis (one of the twopronationmuscles in the wing) on the humerus is placed farther upwards. The femur has a proportionally larger head, and the tibiotarsus has a narrower internal condyle and a distinctive inner cnemial crest that is more pointed and extends further upwards.[3]
Extinction
[edit]All the endemic Caribbean macaws were likely driven to extinction by humans (in prehistoric and historical times), though hurricanes and disease may have contributed. Native Caribbeans hunted macaws and held them captive for later use as food, but also as pets. Since they are known from kitchen midden deposits, the macaws from Puerto Rico and St. Croix were evidently also used for subsistence.[9][15]It is likely that the St. Croix macaw became extinct due to these factors, but the date it happened is unknown.[10]
References
[edit]- ^abcWetmore, A. (1937)."Ancient records of birds from the island of St. Croix with observations on extinct and living birds of Puerto Rico".Journal of Agriculture of the University of Puerto Rico.21(1): 5–16.doi:10.46429/jaupr.v21i1.14340.
- ^Jobling, J. A. (2010).The Helm Dictionary of Scientific Bird Names [electronic resource]: from AALGE to ZUSII.London: Christopher Helm. p.63.ISBN978-1408133262.
- ^abcdefghiOlson, S. L.; Máiz López, E. J. (2008)."New evidence ofAra autochthonesfrom an archeological site in Puerto Rico: a valid species of West Indian macaw of unknown geographical origin (Aves: Psittacidae) "(PDF).Caribbean Journal of Science.44(2): 215–222.doi:10.18475/cjos.v44i2.a9.hdl:10088/6538.S2CID54593515.
- ^Olson, S. L. (1978). Gill, F. B (ed.). "A paleontological perspective of West Indian birds and mammals".Zoogeography in the Caribbean.The 1975 Leidy Medal Symposium: 108.hdl:10088/8455.
{{cite journal}}:CS1 maint: location (link)"Special Publication 13" - ^Olson, S. L. (1983). "Biological archeology in the West Indies".Florida Anthropologist.35(4): 164.hdl:10088/12770.
- ^Wing, E. S. (1989). "Human exploitation of animal resources in the Caribbean". In Woods, C. A.; F. E. Sergile (eds.).Biogeography of the West Indies: Past, Present, and Future(1st ed.). Gainesville: Sandhill Crane Press. pp. 137–152.ISBN978-1-877743-03-0.
- ^abWilliams, M. I.; Steadman, D. W. (2001)."The historic and prehistoric distribution of parrots (Psittacidae) in the West Indies"(PDF).In Woods, C. A.; F. E. Sergile (eds.).Biogeography of the West Indies: Patterns and Perspectives(2nd ed.). Boca Raton: CRC Press. p. 180.ISBN978-0-8493-2001-9.Archived fromthe original(PDF)on 2014-02-07.
- ^Wiley, J. W.; Gnam, R. S.; Koenig, S. E.; Dornelly, A.; Gálvez, X.; Bradley, P. E.; White, T.; Zamore, M.; Reillo, P. R.; Anthony, D. (2004)."Status and conservation of the family Psittacidae in the West Indies"(PDF).Journal of Caribbean Ornithology.17(1): 96.ISSN1544-4953.
- ^abcdWiley, J. W.; Kirwan, G. M. (2013)."The extinct macaws of the West Indies, with special reference to Cuban MacawAra tricolor"(PDF).Bulletin of the British Ornithologists' Club.133:130–131, 137–145, 149–151.
- ^abcHume, J. P.; Walters, M. (2012).Extinct Birds.London: A & C Black. p. 185.ISBN978-1-4081-5725-1.
- ^Forshaw, J. M. (2017).Vanished and Vanishing Parrots: Profiling Extinct and Endangered Species.Clayton: CSIRO Publishing. p. 117.ISBN978-0-643-09632-5.
- ^Turvey, S. T. (2010). "A new historical record of macaws on Jamaica".Archives of Natural History.37(2): 348–351.doi:10.3366/anh.2010.0016.
- ^Gala, M.; A. Lenoble (2015)."Evidence of the former existence of an endemic macaw in Guadeloupe, Lesser Antilles"(PDF).Journal of Ornithology.156(4): 1061–1066.doi:10.1007/s10336-015-1221-6.S2CID18597644.
- ^Olson, S. L.; Suárez, W. (2008). "A fossil cranium of the Cuban MacawAra tricolor(Aves: Psittacidae) from Villa Clara Province, Cuba ".Caribbean Journal of Science.3.44(3): 287–290.doi:10.18475/cjos.v44i3.a3.S2CID87386694.
- ^Nicholls, S. (2009).Paradise Found: Nature in America at the Time of Discovery.Chicago: University of Chicago Press. pp.262–263.ISBN978-0-226-58340-2.