|A "harp" trap being set up at the entrance to Windsor Cave||Artibeus jamaicensis being removed from trap|
The following text is taken from a report by Dr. Michael Gannon of his assessment of the bat colony of Windsor Cave:
The Bats of Windsor Great Cave, Jamaica
Michael R. Gannon, Ph. D.
Department of Biology
The Pennsylvania State University
Altoona College, 3000 Ivyside park
Altoona, PA 16601-3760
Jamaican Conservation Development Trust
Windsor Research Station
Bats are unique keystone species almost everywhere they occur. This is particularly true in tropical and subtropical regions where bats play important roles in insect control, seed dispersal, and pollination. As such, basic knowledge of bat biology and ecology is essential in developing any management plan for the this group.
The Chiroptera remain a little studied group relative to many terrestrial mammals. This lack of research is largely due to the unique and inherently difficult problems of monitoring and observation that bat populations present (Gannon and Willig, 1998). Bats are nocturnal, extremely mobile, and highly variable in their behavior. They are hard to observe under the best situations, and data collection for bats can be laborious. General knowledge of diet, reproduction, roosting habits, and habitat requirements are lacking for many bat species. This is particularly true of the bat fauna of Jamaica where little research has addressed any aspect of bat biology, conservation, or management. Most studies conducted consist simply of species lists for different areas of the island.
Jamaica harbors a unique bat fauna. Of it's 21 known species, 15 are dependent entirely or largely on underground roosts (Fincham, 1997). Although Jamaica has over 1000 caves that have been described and mapped, bats have been documented to occur in only about 17% (Fincham, 1997). This makes those caves of exceptional importance in sustaining bat populations, and ultimately in the maintenance and functioning of the island ecosystem. The purpose of this work is to begin to document the bat species that occur at Windsor Great Cave located in Trelawny (Cockpit Country) of Jamaica, and make recommendations in developing a long term monitoring and conservation plan for the area.
The Bats of Windsor Great Cave, Jamaica are being investigated by Windsor Research Centre in conjunction with J.C.D.T. under the terms of reference of the WWF delegation of management.
Windsor Great Caveis located only a few hundred meters from Windsor Great House (coordinates) in Trelawny (Cockpit Country), Jamaica. It is a large cave, almost 3000 meters in length that runs north-south. A complete cave description, along with a map can be found in Fincham (1997). Windsor Great Cave has long been known to harbor a large population of bats. Most recent estimates are in excess of 50,000 individuals (Vogel, 1997). There are two entrances at the northern end of the Cave.
Previous surveys have been conducted at Windsor Great Cave. Several published and unpublished reports were found, and the number of species recorded by each are summarized in Table 1. It should be noted that voucher specimens for these works are not known to exist at this time. Therefore the identification of specimens for any work previous to this survey could not be verified.
Bat populations were assessed at Windsor Great Cave, Jamaica during July of 1999. Mist nets were used to capture bats by setting them near cave openings at dusk and monitoring them for approximately four hours. The actual number of nets varied depending on the availability of personnel to monitor them. In addition, bats were captured with a hand net as they exited the cave each night for about the first 30 minutes after dusk. Both the upper and lower entrances to Windsor Great Cave were surveyed following this methodology. Upon capture, all bats were assessed as to species, age, weight, and reproductive condition. These data are considered standard in bat research (Wilson, et al., 1996). Field identification of species were made using two different keys (Baker et al, 1984; Fincham, 1977). Age was determined for each individual as evidenced by epiphyseal-diaphyseal fusion of long bones in the wing (Anthony 1988). Reproductive condition of females was recorded as pregnant (based on abdominal palpation), lactating, pregnant and lactating, or inactive (Racey, 1988). A representative sample (maximum of 10 individuals, 5 males and 5 females when possible) of each species was collected and preserved as voucher specimens for the study. The remainder were immediately released. A population index of numerical dominance based on numbers of individuals captured was calculated for each species. This index provides an estimate the importance or dominance of each species of bat present in the survey area compared to all bats present (Gannon and Willig, 1998, Willig and Gannon, 1996). Numerical dominance (ND) for each species was measured as ni/N, where ni is the number of captured individuals of species i and
A total of 228 bats comprising eight different species were captured during the eight nights of this survey at Windsor Great Cave (Table 1). Surveys were conducted for five nights at the upper, larger entrance of the Cave, and for three nights at the smaller lower entrance of the Cave. Total numbers of each species captured can be seen in Table 2. In addition, numbers of each species are reported by locality (upper or lower entrance) as well. Lastly, numerical dominance indices are reported for the Cave overall, and for each entrance separately.
Voucher specimens for each species captured were collected and are housed at the Oklahoma Museum of Natural History. At that locality, identification of all specimens will be confirmed and they will be archived as a permanent record of this study.
All species captured in this study except one have been reported in at least one other survey that previously occurred at Windsor. One individual of Erophylla sezekorni was captured at the upper entrance to Windsor Great Cave. This is a new record for this Cave. The species is considered uncommon or rare on Jamaica.
Over the last 30 years, five reports have appeared that indicate as many as 16 species of bats present in Windsor Great Cave (see Table 1). Most of these surveys took place over only one or two nights, and it is unclear from the reports whether both Cave entrances were surveyed. Any voucher specimens from these surveys have yet been located, so independent verification of these identifications cannot be confirmed. Also, it could not be ascertained, for several of these reports, as to the numbers of each species that were captured, which might indicate whether they were common or rare species. With this information lacking, those data must be viewed with some caution.
In contrast, this study took place over eight different nights and included surveys at both the upper and lower Cave entrances. Voucher specimens for each species were taken, and counts of individuals captured were recorded (Table 2). This study shows differences in species composition and numerical dominance between the two Cave entrances. The upper Cave entrance is dominated by Pteronotus parnellii making up nearly 63% of bats captured, followed by Monophyllus redmani (15%), Tadarida brasiliensis (12%) and Glossophaga sorcina (4%). The lower entrance showed a very different species composition with G. sorcina dominating at 70% of bats captured here, followed by Macrotus waterhousii (9%), Artibeus jamaicensis (7%) and P. parnellii (4%). It is clear that bats are partitioning themselves within the Cave differently and thus different species are using different cave openings as they enter and leave. If we based our assessment on all bats captured regardless of their locality we find P. parnellii making up nearly 50% of the overall numbers of bats captured at Windsor Great Cave, followed by G. sorcina (about 23%), M. redmani (12%) and T. brasiliensis (10%). Had the survey been conducted at only one entrance, we would have concluded that a very different species composition and dominance existed within this Cave.
Several discrepancies exist between data on species composition obtained in this survey and those of other studies. Without voucher specimens to verify identifications, one can only speculate on how and why these occur. It may be possible that each of these species was at one time present in Windsor Great Cave but has since been extirpated for a variety of reasons. However since the Cave has remained relatively undisturbed in the past 30 years, and no major changes have been noted, this explanation is unlikely. It is also possible that the species are present, but extremely rare, making it unlikely that many individuals would be taken. However, without further data, the most plausible explanation at this time would be identification error. One author reported Molossus molossus from Windsor Great Cave. This may possibly be a misidentification as M. molossus is similar in many ways to T. brasiliensis, but is distinguished visually in the field by its smooth upper lip, as opposed to the wrinkled upper lip of T. brasiliensis (Baker et al., 1984). Tadarida macrotis, reported by two authors, is also very similar to T. brasiliensis, but is easily distinguished by its larger size (forearm 56-63 mm as opposed to 36-46 mm for T. brasiliensis, Baker et al., 1984). This may also be a case of misidentification. Phyllonycteris aphylla is closely related to Erophylla sezekorni, and is distinguished based upon the absence of a calcar, which is present in E. sezekorni (Baker et al., 1984). Based on this, the specimen from this study is clearly E. sezekorni. The records by two authors for P. aphylla may reflect such an identification mistake. The record of Noctilio leporinus may also be inaccurate. This is a large bat which feeds primarily on fish. Although they are known from a variety of roost sites including caves near water, they generally roost in large numbers of 30 or more individuals, and often forages in large groups. It is unlikely that such a bat would have gone undetected in so many other surveys if they were present within Windsor.
The most striking discrepancy between this study and others is the absence of any individuals of P. macleayii in the present survey, while it was reported in all of the others. Pteronotus macleayii and P. parnellii are very similar species which are distinguished most easily by their difference in size. Pteronotus macleayii is smaller with a forearm ranging from 42-46 mm while P. parnellii has a much larger forearm of 50 mm or greater (Baker et al., 1984). Forearm measurements for all of the 106 Pteronotus captured during this study were recorded. All were in excess of 50 mm. It is unlikely that so many authors would have been in error when the size difference between these two species is easily distinguishable. At this time, additional data are needed to speculate further on why this species was not found.
With only about 17% of Jamaican caves harboring bats, any such cave is ecologically important to the island. Few caves on the island are reported to have bat populations as large as that of Windsor Great Cave, clearly making it important habitat for bats within the Cockpit Country. Because bats act as seed dispersers, pollinators, and insect control agents, and because this study has shown that Windsor Great Cave harbors large numbers of each, protection of this Cave and the bats within should be of paramount concern to the inhabitants of the region. The Cave still exists in a natural, undeveloped state, and the level of use by tourists and researchers is extremely low. It is unlikely that if such use continues, it will adversely affect the bats. However, this use should be monitored and regulated at its present levels. Full scale tourist development has been suggested for this cave. Any further development would likely disturb and reduce the bat populations. Because the roosting areas of bats are located near the cave entrances, development would cause constant disruption of individuals present and would likely result in a severe reduction or total extirpation the bats from Windsor Great Cave within a short period of time.
As so few caves on Jamaica are suitable for bats, those that are should receive the utmost protection. The Jamaican Conservation Development Trust has already taken steps in protection by hiring a caretaker who is experienced and knowledgeable about bats, keeps records of cave use, and is concerned with the conservation and preservation of this valuable resource. This should continue. Education programs should also be developed in conjunction with tourist visits and for use in the neighboring communities to stress the importance of bats and this valuable resource in the daily life of Jamaicans, particularly those who live and farm in the Cockpit region.
As conservation of biodiversity becomes of increasing worldwide concern, management schemes designed to conserve populations and insure ecosystem stability, need to consider the consequences of temporal variation of populations, whether it be cyclic, directional, episodic, or catastrophic (Gannon and Willig, 1998). Only long-term monitoring of populations can examine such sources of variation. The close proximity of Windsor Great Cave to Windsor Research Station makes it an ideal locality to begin long term monitoring of bats on Jamaica. Initially, monitoring should include population analyses that track changes which may occur over long periods. Ideally, monthly surveys (over several nights each month) should be performed to provide baseline data before any further work is attempted. Recommendations for long-term monitoring techniques that may be employed can be found in Gannon and Willig (1998).
I would like to thank D. Smith, M. Mundle and the Jamaican Conservation Development Trust for providing primary funding for this work . Additional support was provided by the Pennsylvania State University, Altoona College. Logistic support in Jamaica was provided by M. Schwartz and S. Koenig of Windsor Research Station. Field work and data collection were assisted by S. Bryce, H. Davis, D. Holmes, E. Kay, and S. Koenig. I would especially like to thank Franklyn "Dango" Taylor for sharing his knowledge of the cave and for providing technical assistance in the field. Lastly, I would like to thank A. Donaldson and the Natural Resources Conservation Authority for granting permission that made this work possible.
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