Encyclopedia of Islands

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Antillean Mammals

Living Fossils and “Island Shrews”

The surviving solenodons and very recently extinct (if they are extinct) island shrews are like “living fossils” from an earlier and long-extinct North American radiation. They are distributed on Hispaniola, Cuba (and the nearby Cayman Islands), and Puerto Rico (including adjacent Vieques Island). Presumably, solenodontids dispersed from North America to proto-Cuba between 70 and 80 million years ago in the Late Cretaceous, when the proto-Antilles and North America were last connected. They could have dispersed to what is now northern Hispaniola when eastern Cuba and northern Hispaniola were connected during the Oligocene. There is DNA evidence that Solenodon paradoxus and S. cubanus diverged 25 million years ago.

 

This is about the time that eastern Cuba and northern Hispaniola began separating. The dispersal of Solenodon and Nesophontes to southern Haiti and the adjacent southern Dominican Republic could not have occurred until the Late Miocene or Early Pliocene, when the isolated “south island” crunched into true Hispaniola.

DNA analyses suggest that the two solenodons are so genetically divergent that the Cuban form could be considered as a separate genus (Atopogale). Solenodons never radiated into many species (an additional extinct species is known from each island). Solenodon paradoxus has a widespread distribution in the mountains and in appropriate lowland karst zones of southern Haiti and much of the Dominican Republic. In Cuba, Solenodon cubanus is now restricted to the  high karst mountains of eastern Cuba. These living fossils have poor vision and are slow moving. They are easily preyed upon by dogs and the ever more abundant introduced mongoose, so their future survival, even under the best of conservation efforts, is questionable.

ISLAND SHREWS

Endemic “island shrews” of the genus Nesophontes are part of the other soricomorph radiation in the Greater Antilles. The best current hypothesis is that solenodons and island shrews are closely related to each other. Cuba and Hispaniola each have three species of island shrew. In Hispaniola the remains of all three species of Nesophontes are abundant in some cave and sinkhole deposits under barn owl roosting sites. Some bones still have bits of dried tissue on them, and they are often mixed with the fresh-looking remains of introduced rats. The extinction of island shrews in both Cuba and Hispaniola was likely quite recent and may have been caused by competition and predation from black rats and mongooses. It is believed that the final extinction of Nesophontes in both Cuba and Hispaniola may have been as recent as the last 60 years.

In Puerto Rico, there is just one, much larger species (Nesophontes edithae), which may have been an ectomorph of Solenodon. Remains are abundant on the island but are not nearly as recent in appearance as remains from Cuba and Hispaniola, and it is likely that this species became extinct before the arrival of Europeans in the Antilles, and before rats and dogs were introduced.

SOLENODONS

Solenodons are found on Cuba (Solenodon cubanus) and Hispaniola (Solenodon paradoxus). Both are now very rare and are threatened with extinction. Saving these forms from extinction has been given top priority by the Zoological Society of London’s EDGE scheme (Evolutionarily Distinct and Globally Endangered). They are truly evolutionarily distinct, having become isolated from all.

Other Antillean Mammals

Bats are the best known of the other major groups of Antillean mammals. There are 56 known extant species of bats in the Antilles, 28 (50%) of which are endemic. Cuba has the largest and most diverse bat fauna, with 26 living species (plus four extinct and three extirpated species). The next largest assemblage of bats is surprisingly (because it is so much smaller and less diverse than Hispaniola) found on Jamaica, with 21 extant species and three extirpated forms. The much larger island of Hispaniola has 18 extant species and three extinct. In the Lesser Antilles, most major islands have between 10 and 13 extant bat species, with small islands such as Saba (three species) and the Grenadines (four species) having many fewer. Fossil species known from the Lesser Antilles include one extinct form and three locally extinct species (but which still occur in the Greater Antilles). The five most common and widespread species of Antillean bats are Monophyllus redmani, Brachyphylla cavernarum, Artibeus jamaicensis, Noctilio leporinus, and Molossus molossus.

Carnivores appear to be lacking as native species in the Antilles, although they are ecologically present in the form of feral dogs and cats, and the small Indian mongoose (Herpestes javanicus) that was introduced to Trinidad from India in 1870, and has now spread to 29 Antillean islands. The extinct “wild dogs” described from fossils in Cuban cave deposits (Cubacyon and Paracyon) are most likely remains of deformed domestic dogs. There are also reports of native raccoons in the Antilles. Recent molecular studies of the DNA of raccoons have confirmed that what were previously considered to be endemic island species (Procyon maynardi from the Bahamas, P. minor from Guadeloupe, and P. gloveralleni from Barbados) are conspecific with the North American raccoon Procyon lotor.