Encyclopedia of Islands

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Antillean Rodents

The nature of the biodiversity of small organisms such as ants, bees, and forest insects is poorly understood on many islands and archipelagoes but is fabulously preserved in amber deposits of the Dominican Republic. This record, preserved in fossilized resin of a now extinct algarrobo tree (Hymenaea protera), is a record of the broad biodiversity of plants and animals living together in a complex moist tropical forest between 15 and 45 million years ago in the western part of what is now Hispaniola. This tall forest habitat, referred to by George and Roberta Poinar (1999) as the “Amber Forest,” was an ancient forest ecosystem of 40-m-tall canopy trees such as the caoba (Swietenia), the algarrobo (Hymenaea), and the nazareno (Peltogyne), as well as a diverse understory layer of shrubs, ferns, and flowers.

Antillean RodentsThere are few surviving examples of the rich mammalian fauna that characterized the Antilles 18,000 years ago. At that time, land areas of the Greater Antilles were much larger than today because of lower sea levels. The mammals that inhabited these islands included a variety of rodents, sloths, primates, and primitive insectivores. The rich diversity of endemic terrestrial mammals was especially true on the large, topographically diverse islands of Hispaniola and Cuba.

The best-known taxa are members of the rodent family Capromyidae. They are known as “jutias” in Cuba and the Dominican Republic, “zagoutis” in Haiti, and “conies” in Jamaica and the Bahamas. We will call them hutias. They reached high levels of diversity in the Cuban archipelago (five genera, three endemic) and on Hispaniola (four endemic genera). They are not known to have occurred in the Lesser Antilles, but one genus (Geocapromys) with three subspecies occurred in the Bahamas and dispersed to the Cayman Islands and to very small Little Swan Island.

There were at least 55 species, of which 42 have become extinct (76%). The reasons for the extinction of these rodents, many of which were the size of squirrels and large house cats, was likely overhunting by Amerindians, habitat destruction, and predation by introduced dogs, cats, and the mongoose. The largest numbers of surviving hutias occur on Cuba, where 11 species are found in habitats ranging from small isolated offshore islands to mainland Cuban swamps and forested areas. One species (Capromys pilorides) is common throughout Cuba, where it is well known and frequently eaten as “bush meat.” On Hispaniola, the single surviving species of hutia (Plagiodontia aedium) has two extant subspecies, one of which is mainly restricted to southern Hispaniola (P. a. Aedium) and the other to northern Hispaniola (P. a. hylaeum). A closely related hutia (the now extinct Rhizoplagiodontia lemkei) was restricted to the far west of the southern peninsula of Haiti in the Massif de la Hotte. It was very abundant and was part of the cluster of endemic plants and animals that characterized the Massif de la Hotte hotspot.

On Cuba, a fossil rodent of early Miocene age (Zazamys veronicae) has been discovered, which is ancestral to Hispaniolan hutias of the genus Isolobodon. This species, like most other capromyid rodents, was a delicacy, and its remains are common in Amerindian kitchen middens.

“Conies” of the genus Geocapromys still survive in Jamaica and the Bahamas. Thus, it is still possible to observe the last remnants of the once great Antillean radiation of capromyid rodents.

In addition to capromyid rodents, large, heavy-bodied, wide-toothed, hutia-like rodents were present on Jamaica, Hispaniola, and Puerto Rico as well as on two small islands (Anguilla and St. Martin [St. Martin Bank]) in the northern-most Lesser Antilles. Some of these forms, such as the gigantic Amblyrhiza inundata from Anguilla and St. Martin, were as large as 200 kg. These giant rodents (family Heptaxodontidae) were known as “twisted-toothed giant hutias.” They apparently did not radiate into many species, but they were of exceptional mass.

Hispaniola, Cuba, and Puerto Rico shared a radiation of small, spiny, rat-like rodents. They were smaller than hutias in mass and had cheek teeth similar in morphology to South American spiny rats. Two species are common in cave deposits on Hispaniola, and another two species occurred in Cuba. Three species are known from Puerto Rico. The remains of most of these species are fresh in appearance, indicating that they became extinct in historical times, especially on the high plateaus of southwestern Haiti. Remains are common in sinkholes, in cave deposits, and in Amerindian kitchen middens. They were likely driven to extinction by competition from introduced rats and predation by introduced dogs, cats, and possibly even the mongoose.

The radiation of rodents in the Lesser Antilles was much more limited and reflects the very different origin of this long chain of volcanic islands. There are no capromyids, spiny rats, or (with the exception of Anguilla and St. Martin) giant hutias. Instead, the rodents of these small islands were sigmodontine rodents of the genera Oryzomys and Megalomys that made their way onto this chain of oceanic islands by overwater dispersal from South America.

There are described and undescribed taxa of sigmodontines from Anguilla, Antigua, Barbados, Barbuda, Guadeloupe, Marie Galante, Montserrat, St. Eustatius, St. Kitts, St. Lucia, and St. Vincent. One species of Oryzomys is known from Jamaica, which likely dispersed there over water from Central America. All of these forms are now extinct.