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Fraccionamiento de nichos en cuatro murcilagos frugvoros neotropicales: Carollia subrufa, Carollia perspicillata, Sturnira ludovici y Artibeus toltecus
Niche portioning in four frugivorous neotropical bats: Carollia subrufa, Carollia perspicillata, Sturnira ludovici, and Artibeus toltecus
Neotropical bat diversity is high, suggesting finely partitioned niches. Mist nets were set up on edges of Premontane
Moist Forest and secondary forest remnants of San Luis, Costa Rica to examine plant use by frugivorous bats there. I caught 42 frugivorous bats of four species and one nectavorous bat: Carollia subrufa, Carollia perspicillata, Sturnira ludovici, Artibeus toltecus, and Glossophaga soricina The number of Piper, Solanum, and other seeds
were counted and identified in fecal matter to see what each species of bats were eating. The main diet of all 4 species of bats studied consisted of similar species of Piper. Although A. toltecus is known to have a diet consisting of mainly Solanum (Dinerstein, 1981), I found that every A. toltecus fecal sample had only Piper. Though Piper species were not distinguished from one another, their general morphology and accessibility to bats suggest that bats
are not partitioning niches. Instead, all four sympatric bat species seem to be eating the same thing. It could be that all four of these species could coexist because there is an abundance of Piper in the area at present. Because area plants have complex seasonal flowering and fruiting phenologies, the study might have to be repeated at a time of resource depletion to see possible niche partitioning.
La diversidad de los murcilagos Neotropicales es alta, lo que sugiere que los nichos estn finamente divididos. Las redes de niebla se establecieron en los bordes del bosque hmedo premontano y restos de bosque secundario de San Luis, Costa Rica para examinar el uso de las plantas por los murcilagos frugvoros all. Cog 42 murcilagos frugvoros de cuatro especies de murcilagos y un nectavorous: Carollia subrufa, Carollia perspicillata, Sturnira ludovici, toltecus Artibeus y Glossophaga soricina. El nmero de Piper, Solanum, y otras semillas fueron contados e identificados en la materia fecal para ver lo que cada especie de murcilagos estaba comiendo. La dieta principal de las 4 especies de murcilagos estudiadas consista en especies similares de Piper. Aunque A. toltecus se sabe que tiene una dieta que consiste principalmente en Solanum (Dinerstein, 1981), me encontr con que todas las muestras fecales A. toltecus slo tena Piper. A pesar de que las especies de Piper no se distinguan unos de otros, su morfologa general y la accesibilidad a los murcilagos sugieren que los murcilagos no son nichos de particin. En cambio, las cuatro especies simptricas de murcilagos parecen estar comiendo lo mismo. Podra ser que todos los cuatro de estas especies pueden coexistir porque hay una abundancia de Piper en la zona en la actualidad. Debido a que las plantas de la zona tienen complejo de floracin estacional y fenologa de fructificacin, el estudio podra tener que repetirse en un momento de agotamiento de los recursos para ver la posible particin del nicho.
Text in English.
Costa Rica--Puntarenas--Monteverde Zone--San Luis
Diversidad de especies
Costa Rica--Puntarenas--Zona de Monteverde-San Luis
Tropical Ecology Summer 2010
Ecologa Tropical Verano 2010
t Monteverde Institute : Tropical Ecology
N iche portioning in four Frugivorous Neotropical Bats: Carollia subrufa , Carollia perspicillata , Sturnira ludovici , and Artibeus toltecus Gregory Pavur Texas Tech University Fish and Wildlife Management Abstract Neotropical bat diversity is high, suggesting finely partitioned niches. Mist nets were set up on edges of Premontane Moist Forest and secondary forest remnants of San Luis, Costa Rica to examine plant use by frugivorous bats there. I caught 42 frugivorous bats of four species and one nectavorous bat : Carollia subrufa , Carollia perspicillata, Sturnira ludovici , Artibeus toltecus, and Glossophaga soricina . The number of Piper, Solanum, and other seeds were counted and identified in fecal matter to see what each spec ies of bats were eating. The main diet of all 4 species of bats studied consisted of similar species of Piper . Although A. toltecus is known to have a diet consisting of mainly Solanum (Dinerstein, 1981), I found that every A. toltecus fecal sample had onl y Piper . Though Piper species were not distinguished from one another, their general morphology and accessibility to bats suggest that bats are not partitioning niches. Instead, all four sympatric bat species seem to be eating the same thing. It could be that all four of these species could coexist because there is an abundance of Piper in the area at present . Because area plants have complex seasonal flowering and fruiting phenologies, the study might have to be repeated at a time of resource depletion to see possible niche partitioning. INTRODUCTION Costa Rica is the home of at least 108 species of bats, or 11% of the total numbe r of bat species in th e world (LaVal and Rodriguez, 2002) . For them to coexist, the Competitive Exclusion Principle states that these bats would have to partition their resources. Indeed, the feeding guilds of Costa Rica bats include insectivores , frugivores, nectarivores, piscivores , and sangu ivores ( Janzen . 1983) . For example, sympatric bats within a feeding guild may prefe r different habitats, like Sturnira ludovici , and Artibeus toltecus who both feed on Piper but prefer either primary or secondary forests, respectively. Others share habitats but feed at different vertical heights or strat a in the forest, like species Artibeus toltecus and species Carollia perspicillata , feeding low and high in the forest (LaVal and Rodriguez, 2002) . Sympatric frugivorous bats such as Carollia subrufa , Carollia perspicillata , Sturnira ludovici , and Artibeus toltecus all live in San Luis , Costa Rica. These bats forage in similar habitat and similar strata and appear to feed on similar fruits, though there are certain preferences (Dinerstein, 1983) .
Bats are able to coexist through evolving a specific niche that allows them to compete with other bats. Frugivores bats such as the Carollia subrufa , Carollia perspicillata , Sturnira ludovici , and Artibeus toltecus have developed niches to eat certain fruits ( Aguirre et al. 2003 ) . Bats will specialize in plants that live in primary and secondary forest. Some frugivores bats will specialize in eati ng fruit at different canopy levels. Fecal matter is taken from the bats to identify the fruit seeds that are in their diet. Mist nets are set up to catch bats in the forest and on the forest edges. Frugivores in this study are mainly found around Piper and Solanum plants. As stated previously, the Competitive Exclusion Principle dictates that bats sharing resources in the same way should not coexist (Ambrose et al. 2002) . How, then, do C. subrufa , C. perspicillata , S. ludovici and A. toltecus do it? While Dinerstein (1983) did not find compelling evidence for competition and niche partitioning in these species, resources vary from year to year and even month to month. It is possible that his study was performed in year of unusual fruit abundance or some other anoma ly. Here, I repeat species. MATERIALS AND METHODS STUDY AREA AND SITE DESCRIPTION San Luis is located in a P re montane M oist F orest found in Costa Rica . Mist nets were always in or near forest. One site was a cattle farm and another had a fruit garden near by . The third study site was deep in forest. Two sites were located on trails inside the forest. All three study areas were between 1100 1200 meters. I set up mist nets in three different areas at each site . The mist nets were set up around fruiting Piperacea plants that C. subrufa , C. perspicillata , S. ludovici , and A. toltecus would eat. Dinerstein (1983) shows that in the month of July , Piper ( Piperaceae ) and Solanum (Solanaceae ) are fruiting and all four species of bats mentioned above feed on these two plants (Dinerstein, 1983) . I was not able to find any Solanum plants around the study areas but some Piper was seen at two study areas. The entire study was conducted over 13 nights in July. At two sites I set up three mist nets that were attached to two poles. The nets were set up in the trails in the forest because the bats would use the relatively open trails as fly ways . In t he second s ite , I placed two mist nets on the edge of the forest. The nets were only set up on nights when it was not raining. After two to three nights I would move the bat nets 20 40yards in each study area because the bats would start to avoid the nets if they wer e left in the same area every night. I would open the nets at 5pm and close them at 10pm. After opening them I would check each net every 15 minutes to check to see if any bats flew into them. I would take each bat out of the net with gloves and place the bat into a bat bag for 15 minutes to allow the bat to defecate. About 70% of the time the bat would defecate on the glove when the bat was taken out of the net. I placed the fecal matter in a vile and put some alcohol into the vile to preserve the fecal ma tter. After catching bats I looked at the fecal matter underneath a microscope and used a dissecting kit to examine the fecal matter. I in the fecal matter . RESULTS
Samples were taken from a total of 47 bats that consisted of five different species of bats , not just the four I expected . I obtained samples from three Carollia subrufa , twenty seven Carollia perspicillata , six Sturnira ludovici , seven Artibeus toltecus , and four Glossophaga soricina. G. soricina is a nectarivorous bat, but with fruit seeds in its droppings. All species preferred to eat Piper than Solanum as you can see in figure one with the total seed counts of each species. I found a difference in the total number of seeds per bat species ( = 32.31,DF = 8, P< 0.05 ; Ambrose et al. 2002). C. perspicillata had many more seeds overall, even after accounting for the relative number of individuals in my sample. (FIGURE: 1) TABLE 1. All species preferred Piper over other fruit plants. C. subrufa and A. toltecus did not eat any Solanum. A. toltecus only ate Piper plants while C. perspicillata and S. ludovici consumed Piper, Solanum , and other fruits. C. perspicillata C. subrufa S. ludovici G. soricina A. toltecus Piper 26 3 4 3 7 Solanum 4 0 2 1 0 Other 4 1 2 0 0
FIGURE 1. This figure shows that a total of three S. ludocici ate 39 Piper seeds, 15 Solanum seeds, and 8 other seeds. Twenty seven total individuals of C. perspicillata ate 1,179 Piper seeds, 12 Solanum seeds, and 107 other seeds. Seven total individuals of A. toltecus ate only Piper seeds in their diet consisting of 81 seeds total. A total of three C. subrufa ate 47 Piper seeds and 8 other seeds. All four species preferred to eat more Piper than Solanum or other fruits.
FIGURE 2 . The fecal matter of 4 G. soricina consisted of 102 Piper seeds and 1 Solanum seed. G. soricina is a nectavorous bat that preferred mainly Piper plants. Additional Observations G. soricin a was the only non frugivores bat that I caught and obtained a fecal sample from. G. soricin a is a nectavorous bat and I obtained 4 fecal samples from 4 individuals. The G. soricin a preferred more Pip er over Solanum as seen in figure 6. DISCUSSION Piper and Solanum were both present in all the study areas but I do not know which study areas contain higher concentrations of Piper plants or Solanum . I know that Piper and Solanum were present in each study site because both species of plants were found in the fecal matter at all three study areas . Piper and Solanum are both normally fruiting during the study in July (LaVal, 2003) . It is unknown why all species preferred Piper over Solanum o r other fruits. Dinerstein (1983) shows S. ludovici, C. pers picillata , and C. subrufa all consume more Piper than Solanum (Dinerstein, 1983) . Dinerstein does show that each of these three species eats Solanum as well, and all three of these species did consume small quantities of Solanum in this study . A. toltecus is shown to eat mostly Solanum and very small amounts of Piper according to Dinersteins results (Dinerstein, 1983) . On the contrary, my study shows that A. toltecus consumed only Piper (Figure 1) . This could mean that more Piper was in the area and very little Solanum was around. This could also suggest that Solanum plants are preferred and, hence, depletd in the area . Perhaps A. toltecus are adapting to consume more Piper in their diet The fact that a nectarivorous bat had seeds in its droppings is interesting. G. soricina could be feeding on fruits when flowering plants are not blooming. The G. sorici nectar. Since four individuals were captured and retrieved samples from that had fruit seeds in their fecal matter, could suggest that G. soricina are changing their diet. Stud ies have shown that G. soricina will occasionally eat insects and fruits while there are low numbe rs of flowers in the area (Patterson et al. 2003). 99% 1% Glossophaga soricina Piper Solanum
I am assuming that all four species that I studied do not have the same niche because they are coexisting together. Different species of bats were caught at different times of the night which can suggest that different species are feeding at different times. Perhaps different species of bats are eating different species of Piper in order to coexist with one another. I only looked to see if the seeds were in the family of Piper and did not identify which sp ecies of Piper . These bats may be acquiring niches for specific species of Piper . The bats could be feeding only in certain areas of forest or feeding at different times of night. ACKNOWLEDGMENTS Special thanks are due to Moncho Calderon, Eduardo Leiton , Arturo Cruz , Dan Dempsey, Tiffany Reeves, John Colantonio, and Mackenzie Most for helping me catch bats and taking samples of the fecal matter. I really enjoyed working with you Dan Dempsey, we worked hard and made our projects work out and be successful . You made San Luis showing me where the bats like to fly. I owe you a big thanks Arturo being there whenever I needed help. I think I would hav appreciate Moncho and Alan Masters helping me throughout the project telling me what to do and what not to do. I also owe a big thanks to Milten Brenes and the University of Georgia for allowing me to catch bats on their property. LITERATURE CITED Aguirre, C.F., A. Herrel, R. Van Damme and E. Matthysen. 2003. The im plications of food hardness for diet in bats . Functional Ecology. Vol. 17, No. 2. Pg. 201 212. Ambrose, W. Harrison., Ambrose, Katharine., Emlen, Douglas., Bright, Kerry. 2002. A Handbook of Biological Investigation. Sixth edition. Hunters Textbooks. Dinerstein, Eric. 1983. Reproductive Ecology of Fruit Bats and Seasonality of Fruit Production in a Costa Rican Cloud Forest . University of Washington. Janzen, H. Daniel. 1983. Mammals . Costa Rican Natural History. University of Chicago Press. Pg. 426 448. LaVal K. Richard, Rodriguez H Bernal. 2002. Murcielagos de Costa Rica Bats. Instituto Nacional de Biodiversidad. Patterson, D.B., M.R. Willig, and R.D. Stevens. 2003 . Trophic Strategies, niche Partitioning, and patterns of Ecological organization . Bat Ecology. University of Chicago Press.pg.536 568.