... SPECIES DIVERSITY OF BATS AT SPRINGFIELD ESTATE Cary Labrenz Texas A&M University Dominica Study Abroad Research June 8, 1998

Transcription

1 ... SPECIES DIVERSITY OF BATS AT SPRINGFIELD ESTATE Cary Labrenz Texas A&M University Dminica Study Abrad Research June 8, 1998

2 SPECIES DIVERSITY OF BATS AT SPRINGFIELD ESTATE Cary Labrenz Texas A&M Uni"ersity Dminica Study Abrad Research Intrductin There are twelve bat species that have been bserved n Dminica, tw f which are endemic t the Lesser Antilles. Bats are essential fr insect cntrl and pllinatin n Dminica. These ncturnal mammals rely heavily n echlcatin while they frage. The purpse f this prject was t determine species deversity f bats in Springfield. Hpefully this prject will be a useful guide fr future bat research prjects. Fr this reasn, nt nly was species diversity recrded, but net placement, time f capture, and general weather cnditins were als nted. Materials and Methds T capture the bats, mist nets 6 meters lng were set up. Bamb was cut with a machete t abut 9 feet lng t make ples. Bamb ples were chsen that were abut 2 inches in diameter s the mist net culd easily slip ver. A pst hle digger r shvel was used t dig hles abut 1 ft deep t place ples. Rpe and stakes were used t secure the ples. Six nets were placed at different lcatins. The lcatins were the stream, bee huse, dining area, streamhuse, and tw at Mt. Jy. The nets were placed during the day, and a different net was drpped each night. Nets were drpped arund dusk (between 6 and 7 pm) except fr the dining net which culd nt be drpped until after dinner (arund 9 pm). When a net was nt in use it was flded n itself and held tgether with clse pins. Species, sex, time f capture, parasite cllectin, and tissue samples were recrded r cllected fr each bat. Bats were remved frm the net and released nce identified and prcessed. [f pssible, each lcatin was dne twice. The fllwing are descriptins f net placement at different lcatins. 1. Stream -Net placed at abut a 45 degree angle frm the stream t the bank alng side. net a-ttnil 2. Mt. Jy -First net placed parallel t remains fmt. Jy huse in the grass. -Secnd net placed further up the trail frm the huse in a clearing just ff the "I tnu. '" ---- :>04 Mt. h~~ " \' t cl nbf- \;7.n ' ~{((-!jra-'s~~ ~.. I I l~ner 3. Stream huse -Net placed diagnally acrss a crner f the secnd flr balcny...".l.-.' _

3 4. Dining area -Net placed diagnally frm table where fd is served t railing. a Ii 5. Bee huse Kitchen -Net placed between the pnd and trail in a clearing between trees. ~ Results Three species f bats were caught in the nets that were placed: Artibeus jamaicensis, Mlssus mlssus, and Stumira lilium. A. jamaicensis is a large brwn fruit eating bat, and is ne f several leaf nsed bats in Dminica. M. mlssus is a very small, redish- brwn free tail bat that has very velvety fur and eats insects. S. lilium is a small, dark brwn fruit eating bat with reddish shulders and a nseleaf Bats were nly caught at three f the lcatins: bee huse, stream, and stream huse. The fllwing is a sample data sheet thatwas used t recrd bat infrmatin, net lcatin, time f net use, and weather : D[1;fe: Lcatin: Wea,iher: Net drtp 1irYlt. Ntt up tlrne.,: I N f 5~GS ISex/11m< r ~I fnxtwrg. I The fllwing data represents the species and frequency at each lcatin and the ttal number f bats caught at each lcatin. Lcatin Mt. Jy Bee Huse Stream Stream Huse Dining Area A. jamaicensis 1 7 M. mlssus 2 30 S.lilium 3 1 Ttal 4 IO 30 See Figure 1 als. Percentages f species at each lcatin was 25% A. jamaicensis and 75% S. lilium at the bee huse, 70% A. jamaicensis, 10% S. lilium, and 20% M. mlssus at the stream, and 100% M. mlssus at the stream huse. See Figure 2. Discussin Six nets were set up in 5 different areas f the Springfield estate. Bats were caught at the stream, stream huse, and bee huse. N bats were caught at Mt. Jy r the dining area.

4 A ttal f 44 bats were caught. Three species f bats caught were Artibeus jamaicensis, Mlssus mlssus, and Stumira lilium. At the stream huse nly Mlssus mlssus were caught. This is mst likely because the Mlssus are rsting in the rf f the stream huse. The bats caught were either leaving r returning t the rst in the rf This bservatin became the center f tw classsmates' bat prject. It was als interesting that f the 30 mlssus caught, nly ne was male, and six f the females were pregnant n palpatin. This suggests that the mlssus may live in harem grups r the clny might be a nursing clny. At the bee huse S. lilium was the predmininant species caught. The net was placed in an pen area by the pnd t catch bats in their flight path t drink water. The stream net had the mst species diversity f bats. Althugh A. jamaicensis was the clear majrity, sme M. mlssus and S. lilium were als caught. The stream was chsen as a lcatin because it was a big clearing near running water which bats culd fly thrugh t get water. Althugh I bserved bats in the dining area after dinner, all three attempts at netting were unsuccessful. I bserved bats feed n the insects attracted t the light in the dining area, s the net was put in the dining areaa with the same light n. It was questinable whether r nt the bats culd see the net with the light n, but if the light was ff then there wuld be n bugs fr bats t feed n. This dilemma culd be why n bats were caught. Anther prblem was that it rained n and ff everytime we netted in the dining area. I bserved that when it rained at the bee huse ne night, bats were caught befre the rain started, but n bats were caught after the rain started. The rain culd be anther reasn why n bats were caught at the dining area. N bats were caught at Mt. Jy in either net. Net placement culd be a pssible reasn. Placing the net(s) at different angles in the clearings at Mt. Jy might be mre successful. Als, the night at Mt. Jy that netting was attempted, the sky was very clear. Bats usually fly less in the clearings and mre in the trees t avid predatrs in these cnditins. Since bats are ncturnal, the nets were drpped at dusk, presumably just befre bats leave the rst. Bats were caught as early as 6:45 pm and as late as 10: 15 pm. N nets were left dwn later than 11:43, s n data was cllected fr this prject after that time. Hpefully this infrmatin will give future bat prjects in Dminica a place t start as far as lcatin and species diversity s that mre extensive research can be attempted. Wrks Cited Carvan, Paul Bat Prject Dminica. Evans, Peter and Arlingtn, James Dminica Nature Island f the Caribbean: Checklists. Vl. 2, Rseau Kricher, Jhn C Netrpical Cmpanin Wildlife New Jersey: Princetn University Press.

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