St. Croix macaw

Species of extinct macaw

The St. Croix macaw (Ara autocthones) or Puerto Rican macaw is an extinct species of macaw whose remains have been found on the Caribbean islands of St. Croix and Puerto Rico. It was described in 1937 based on a tibiotarsus leg bone unearthed from a kitchen midden at a pre Columbian site on St. Croix. A second specimen consisting of various bones from a similar site on Puerto Rico was described in 2008, while a coracoid from Montserrat may 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 extinct Cuban macaw (Ara tricolor). Only the blue throated macaw (Ara glaucogularis) and Lear's macaw (Anodorhynchus leari) are similar in size. It differed from other macaws in various skeletal details and shared several features with only the genus Ara. 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.

In 1934, the archeologist Lewis J. Korn (working under the Museum of the American Indian) excavated a kitchen midden (a dump for domestic waste) at a site near Concordia on the southwestern coast of St. Croix, one of the Virgin Islands in the Caribbean Sea. The midden was located inland from the beach, and its depth was around 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 be pre Columbian, between 500 and 800 years old. 23 species of birds were represented among the well preserved bones, some of which were extinct. In 1937, the ornithologist Alexander Wetmore identified several species among these bones, including a left tibiotarsus (lower leg bone) of an immature macaw, which was unexpected since no such birds were previously known from St. Croix. In 1983, he indicated that if the macaw had indeed been transported, the specific name would be a misnomer. The zoologist Elizabeth S. Wing agreed in 1989 that the macaw could have been traded, 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. 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 the Cerrillos Bucaná river in south central Puerto Rico. The archeological site represents a pre Columbian Saladoid Ostionoid village of around 15,000m2 (3.7acres) in size, situated on an alluvial 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 left coracoid (missing a portion of the bone's "head"), both ends of the left humerus, the upper end of the right radius, the left carpometacarpus (missing one metacarpal), the left femur (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 to Ara autocthones (it had been assigned to Ara sp. in 2004, indicating uncertain classification within the genus Ara), as its tibiotarsus is identical in size to the holotype. Olson and Máiz López considered it likely that Ara autocthones was endemic to the West Indian region 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 name autocthones "probably one of the worst possible choices" for the species. Though fossils of the parrot genera Amazona and Aratinga have 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 Americansfor example the Puerto Rican hutia (Isolobodon portoricensis, an extinct rodent) and the Antillean cave rail (Nesotrochis debooyi, an extinct flightless rail) were both transported to St. Croix and found in kitchen middens. The ornithologist Joseph M. Forshaw argued 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. 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 only hypothetical species. 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 and subfossils, and the Lesser Antillean macaw is possibly known from subfossils. Macaws are known to have been transported between the Caribbean islands and from mainland South America to the Caribbean, both in prehistoric times by Paleoamericans and in historic times by Europeans and natives. Parrots were important in the culture of native Caribbeans and were among the gifts offered to the explorer Christopher Columbus when he reached the Bahamas in 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.

Since only bones are known of the St. Croix macaw, nothing can be said about its coloration.

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. It is likely that the St. Croix macaw became extinct due to these factors, but the date it happened is unknown.