Chiroptera Neotropical 16(1), July 2010 BATS OF THE GRENADINE ISLANDS, WEST INDIES, AND PLACEMENT OF KOOPMAN’S LINE Hugh H. Genoways1*, Gary G. Kwiecinski2, Peter A. Larsen3, Scott C. Pedersen4, Roxanne J. Larsen3, Justin D. Hoffman5, Mark de Silva6, Carleton J. Phillips3, and Robert J. Baker3 1. University of Nebraska State Museum, W436 Nebraska Hall, Lincoln, NE 68588. U.S.A. 2. Biology Department, University of Scranton, 800 Linden Street, Scranton, PA 18510. U.S.A. 3. Department of Biological Sciences and Museum, Texas Tech University, Lubbock, TX 79409 . U.S.A. 4. Department of Biology and Microbiology, South Dakota State University, Brookings, SD 57007. U.S.A. 5. Department of Biological and Health Sciences, McNeese State University, MSU Box 92000, Lake Charles, LA 70609. U.S.A. 6. P.O. Box 860, Kingstown, St. Vincent and the Grenadines. * Corresponding author. Email: [email protected] Abstract. Almost nothing is known concerning the chiropteran fauna on the Grenadine Islands, a chain of islands between St. Vincent and Grenada located near the southern end of the Lesser Antilles. Previously, only a single species—Glossophaga longirostris—had been reported from the Grenadines. Our research, conducted on 4 occasions over the period of 1980 to 2006, provided museum vouchers and genetic specimens for the addition of 4 other species to the known fauna of these islands—Noctilio leporinus, Artibeus lituratus, Artibeus schwartzi, and Molossus molossus. The Grenadines, being situated between St. Vincent and Grenada, occupy an important zoogeographic position. None of the 12 species of bats occurring on Grenada are Antillean endemics, whereas on St. Vincent, to the north of the Grenadines, 3 of the 12 species are Antillean endemics. The boundary of the West Indian Subregion of the Neotropical Region based on the distribution of mammals has been designated as Koopman’s Line. One of the areas where placement of Koopman’s Line was unresolved was among the Grenadine Islands because the chiropteran fauna of this area was essentially unknown. Based on data reported herein, we place Koopman’s Line along the 14-km wide Bequia Channel that separates St. Vincent and the northern-most Grenadine island of Bequia. Keywords: biodiversity, Chiroptera, Grenadine Islands, Koopman’s Line, systematics, zoogeography. Introduction sedimentary elements (Beard 1949). Although The Grenadines are a series of nearly 200 politically divided, the Grenadines are islands, islets, cays, and rocks in the southern geologically united along the narrow 4000 square Lesser Antilles. Geographically, the Grenadines km platform known as the Grenada Bank. The span a 110-km stretch of water between St. 14-km wide Bequia Channel separating St. Vincent in the north and Grenada in the south. At Vincent and Bequia, which reaches a depth of least 7 of the islands have permanent settlements 1100 m, marks the northern end of the Grenada and some of the other smaller islets have been Bank. Channels ranging from only 22 to 37 m converted into resorts. Today, tourism is the deep separate the islands along this bank, which main industry in the Grenadines and is the cause extends at this depth approximately 30 km to the of considerable development on many of the southwest of Grenada, although without islands. islands. The Grenadines are divided politically, The Grenadine islands were united with Grenada with those islands north of the Petite Martinique to form a single elongate island during the Last Channel (Fig. 1) being part of the nation of St. Glacial Maximum (26,500 to 19,000 years before Vincent and the Grenadines—major islands present; Clark et al. 2009), resulting from a including Bequia, Mustique, Canouan, Mayreau, Pleistocene sea level lowering of 120 to 135 m and Union—and those south of the channel being (Watters 1989). part of the nation of Grenada—the only major Although the chiropteran faunas of St. Vincent island is Carriacou, whereas Petite Martinique is (Vaughan and Hill 1996) and Grenada much smaller. (Genoways et al. 1998) have been studied in The Grenadine islands are primarily of volcanic recent years, almost nothing is published origin, but many also include uplifted concerning the intervening fauna on the 501 Chiroptera Neotropical 16(1), July 2010 Grenadines. Allen (1908) was the first to record specimens under the name Glossophaga bats from the Grenadine islands when he longirostris rostrata (Miller 1913a). The only presented data on a series of Glossophaga other mention of Grenadine bats was by Jones longirostris from Carriacou and Union Island (1989) when he included 4 species from the deposited in the Museum of Comparative islands in his table on the distribution of bats in Zoology, Harvard University. These same the Lesser Antilles. These species occurrences vouchers were reported again by Allen (1911) in were reported without reference to specific his classic “Mammals of the West Indies” and by localities or islands, and were based on bats Miller (1913b) in his revision of the genus captured during the early phase of our research. Glossophaga. Miller (1913b) reported these Figure 1. Map showing the Grenadine islands, St. Vincent, and Grenada at the southern end of the Lesser Antilles. The Bequia Channel marks the position of Koopman’s Line. The Petit Martinique Channel is the dividing point between the nations of St. Vincent and the Grenadines and Grenada. The Grenadines, being situated between St. support the conclusion that all species of bats Vincent and Grenada, occupy an important inhabiting islands in the Caribbean region arrived zoogeographic position (Genoways et al. 1998). by over water dispersal or evolved in place In 1987-88, nucleotide restriction site mapping of (Baker and Genoways 1978; Hedges 2006; Pregill bat mitochondrial genomes was employed for the 1981; Morgan and Woods 1986; Pumo et al. first time on the Caribbean fauna, and based on 1988, 1996; Phillips et al. 1989, 1991). To the these data it was hypothesized that the Grenadines south of the Grenadines, the chiropteran fauna of acted as a “filter” to northward or southward Grenada consists of species that either invaded dispersal by bats (Phillips et al. 1989). This was from such areas as Trinidad or the South an important hypothesis because all current data American mainland or are species that are so widespread in their distribution that no particular 502 Chiroptera Neotropical 16(1), July 2010 route of invasion can be determined at this time fruit-eating bats. A dense, shrubby under story is (Genoways et al. 1998). None of the species of often dominated by rough velvet seed (Guettarda bats occurring on Grenada are Antillean scabra), cucubano de vieques (G. odorata), false endemics, whereas on St. Vincent, to the north of chiggergrape (Coccoloba venosa), and lancewood the Grenadines, 3 of the 12 species are Antillean (Nectandra coriacea). Low lying coastal areas endemics that are characteristic of the Lesser are dominated by red mangrove (Rhizophora Antilles (Vaughan and Hill 1996). Two of these mangle), black mangrove (Avicennia germinans), species—Monophyllus plethodon and and manchineel (Hippomane mancinella). A Brachyphylla cavernarum—occur from Puerto number of species of regional and introduced fruit Rico southeastward to St. Vincent and Barbados. trees add to the diversity of plants on the islands The third species—Ardops nichollsi—is a Lesser and foods available to bats, but nowhere in the Antillean endemic, but does not occur on Grenadines have we seen these trees occurring in Barbados. The foregoing data and analyses led managed plantations, including mangos Genoways et al. (1998) to place the boundary of (Mangifera indica), banana (Musa sp.), coconut the West Indian Faunal Subregion, designated by palm (Cocos nucifera), guava (Psidium guajava), them as Koopman’s Line, between St. Vincent guinep (Melicoccus bijugatus), sapodilla and Grenada. They opined that once the (Manilkara zapota), nutmeg (Myristica fragrans), chiropteran fauna of the Grenadines was known, lime (Citrus latifolia), and soursop (Annona it could be “that Koopman’s Line may eventually muricata). be found to bisect the Grenadines” (Genoways et All of the islands are relatively low lying, with al. 1998: 20). the highest elevation just over 300 m. Because of The goals of our field research in the Grenadine these low elevations, none of the islands creates islands were a) to describe the biodiversity of the its own weather, making all of the islands chiropteran fauna occurring on the islands and b) comparatively arid (Beard 1949), with annual to use this information to refine our understanding rainfall being in the range of just over 100 cm. of West Indian zoogeography by determining the The islands do have arid-adapted thorny plants, placement of Koopman’s Line in the region. including prickly pear cactus (Opuntia dillenii), Refining our understanding of geographic century plants (Agave caribaeicola), and several placement of Koopman’s Line or, alternatively, species of acacia (Acacia). The driest part of the discovering that it is more of a region than a year is from December to late April. Annual narrow zone, is the first step to testing hypotheses temperatures range from 27º to 32º C. about ecological or other factors involved in the The Grenadines lie near the southern boundary zoogeographic phenomenon. To this purpose, we of the Caribbean hurricane belt, thus experience conducted field research during 4 years in the fewer hurricane-strength tropical storms than Grenadines, including 1980, 1986, 2005, and islands further to the north. Hurricane Janet in 2006. Our work has resulted in the collection of September 1955 caused major damage in the 395 voucher specimens of 5 species. These data islands. More recently, Hurricane Ivan in are reported herein. September 2004 and especially Hurricane Emily in July 2005 caused damage in the Grenadines, Materials and Methods particularly on Carriacou (Caribbean Hurricane Study area. The Grenadine islands are volcanic in Network 2008).