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Burkard, Gregory Paul, Jr.
Depredacin de semillas de Persea americana por Dasyprocta punctata en Monteverde, Costa Rica
Seed predation on Persea americana by Dasyprocta punctata in Monteverde, Costa Rica
Digitized by MVI
Dasyprocta punctata (Rodentia: Dasyproctidae), a scatter-hoarding rodent, plays an important role in seedling recruitment and tropical forest composition. (Herrera and Pellmyr 2002) The purpose of this study was to see if D. punctata maximizes its fitness by behaving as a density-dependent forager, and if the scatter-hoarding caching behavior of D. punctata is aiding the fitness of Persea americana (Lauraceae). P. americana seeds were presented to D. punctata in three distinct densities at the Santuario Ecolgico in Cerro Plano, Costa Rica to observe individual seed fate. No significant difference was found for the fates of P. americana seeds between the three densities (p = 0.8651, Chisquare = 0.2900, df = 2). However, more seeds were cached than eaten, partially eaten, or untouched (Two-way ANOVA, p = 0.0002, < 0.0001, < 0.0001, respectively, df = 3). This study gives evidence that D. punctata is a density-independent forager, possibly due to seed satiation (overabundance of seeds), which aids the fitness of P. americana via caching.
Dasyprocta punctata (Rodentia: Dasyproctidae), es un roedor que deposita las semillas debajo de la tierra; este animal juega un papel importante en el reclutamiento de semillas y en la composicin del bosque tropical (Herrera y Pellmyr 2002). El propsito de este estudio fue determinar si D. punctata maximiza sus adaptaciones al comportarse como un depredador dependiente de la densidad, y si el comportamiento de esconder las semillas ayuda a Persea americana (Lauraceae). Las semillas de P. americana fueron presentadas a D. punctata en tres densidades diferentes en el Santuario Ecolgico en Cerro Plano, Costa Rica, para observar el destino de cada semilla. No se encontraron diferencias significativas para el destino de las semillas de P. americana entre las tres densidades (p = 0.8651, Chi-square = 0.2900, df = 2). Sin embargo, enterraron ms semillas de las que se comieron, fueron parcialmente comidas, o no las tocaron del todo (ANOVA, p = 0.0002, < 0.0001, < 0.0001, respectivamente, df = 3). Este estudio proporcion evidencia de que D. punctata es un depredador independiente de la densidad de semillas; posiblemente debido a la saciedad (Sobreabundancia de semillas), lo que ayuda a la adaptacin de P. Americana.
Text in English.
Central American agouti
Costa Rica--Puntarenas--Monteverde Zone--Cerro Plano
Costa Rica--Puntarenas--Zona de Monteverde--Cerro Plano
Tropical Ecology Fall 2005
Ecologa Tropical Otoo 2005
t Monteverde Institute : Tropical Ecology
Seed Predation on Persea americana by Dasyprocta punctata in Monteverde, Costa Rica Gregory Paul Burkard Jr Department of Comprehensive Sciences, Villanova University ABSTRACT Dasyprocta punctata (Rodentia: Dasyproctidae) a scatter hoarding rodent, plays an important role in seedling recruitment and tropical forest composition (Herrera and Pellmyr 2002). The purpose of this study was to see if D. punctata maximizes its fitness by behaving as a density dependent forager, an d if the scatter hoarding caching behavior of D. punctata is aiding the fitness of Persea americana (Lauraceae). P. americana seeds were presented to D. punctata in three distinct densities at the Santuario Ecolgico in Cerro Plano, Costa Rica; to observe individual seed fate. No significant difference was found for the fates of P. americana seeds between the three densities (p = 0.8651, Chi square = 0.2900, df = 2). However, more seeds were cached than eaten, partially eaten, or untouched (Two way ANOVA p = 0.0002, < 0.0001, < 0.0001, respectively, df = 3). This study gives evidence that D. punctata is a density independent forager, possibly due to seed satiation (overabundance of seeds), which aids the fitness of P. americana via caching. RESUMEN Dasyprocta punctata (Rodentia: Dasyproctidae) es un roedor que deposita semillas debajo de la tierra; este animal juega un papel importante en el recrutamiento de semillas y en la composicin del bosque tropical (Herrera and Pellmyr 2002). El propsito de este estudio fue determinar si D. punctata maximiza sus adaptaciones al comportarse como un depredador dependiente de la densidad, y si el comportamiento de esconder las semillas ayuda a Persea americana (Lauraceae). Las semillas de P. americana fuero n presentadas a D. punctata en tres densidades diferentes en el Santuario Ecolgico en Cerro Plano, Costa Rica, para observar el destino de cada semilla. No se encontraron diferencias significativas para el destino de semillas de P. americana entre las tres densidades (p = 0.8651, Chi square = 0.2900, df = 2). Sin embargo, ms semillas fueron enterradas que comidas, parcialmente comidas, o no manipuladas (ANOVA, p = 0.0002, < 0.0001, < 0.0001, respectivamente. df = 3). Este estudio proporcion evidenci a de que D. punctata es un depredador independiente de la densidad de semillas; posiblemente debido a la saciedad (Sobreabundancia de semillas), lo que ayuda a la adaptacin de P. Americana INTRODUCTION Janzen proposed the theory of density depen dent predation in 1970 (Janzen1970). Which states that as the density of seeds around trees increases, the probability of a particular seed being preyed upon increases as well (Janzen 1970, Herrera and Pellmyr 2002). This occurs for two reasons; reward a pparentness and potential fitness gain (through nutrition) for the predator. Plants and seeds that are more apparent to their predator experience higher rates of herbivory (Rhoades and Cates 1976). Thus something that is visually attractive in quantity o r in clumps, such as seeds, is more easily found and preyed upon. Predators have evolved to maximize fitness when foraging as stated in the optimal foraging theory, therefore it is more advantageous to feed in denser seed areas and on larger crops (Herrer a and Pellmyr 2002). Larger crops offer bigger rewards, usually resulting in a greater chance of attracting seed predators (Herrera and Pellmyr 2002). Thus, seed predators are foraging for the two previously stated reasons, apparentness and potential fi tness gain. This behavior supports the density dependent predation
theory because it is advantageous for predators to feed in denser areas by minimizing the cost of searching for seeds. Density dependent seed removal amongst rodents is common for small s eeds, but limited experiments and data suggest rodents do not respond to differences in seed frequency (Hulme and Hunt 1999). Scatter hoarding is a practice in which rodents and small mammals remove seeds from the parent tree and bury them in the earth intending to return when resources are low (Herrera and Pellmyr 2002). This technique of scatter hoarding and caching is crucial to the survival and reproduction of rodents (Herrera and Pellmyr 2002, Levey et al. 2002). It is by this method that rodent s create several shallow caches with a low density of seeds, which may lead to germination if recovery is not complete (Herrera and Pellmyr 2002, Levey et al. 2002). If rodents do not recollect all the seeds, they are aiding the fitness of the plant by pr oviding protection from other seed predators, as well as a substrate in which to grow (Herrera and Pellmyr 2002). Scattering is beneficial, because if a seed predator, such as the peccary finds one cache, only a few seeds will be found and it does not aff ect the fitness of the tree. Also, scatter hoarding caches are generally shallow, resulting in the ideal position for seeds to germinate (Herrera and Pellmyr 2002). The seed germination for scattered hoarded seeds is generally low, but a previous study f ound that survival and germination ranges from .75 10% for Gustavia superba (Forget 1992). Despite the fact that germination is low, scatter hoarders have important indirect effects on trees. Scatter hoarders can greatly impact the fitness of trees and forest diversity even though germination of cached seeds is low. The Central American agouti, Dasyprocta punctata (Rodentia, Dasyproctidae) is the most common diurnal mammal in low to mid elevation rainforest in Central America (Smythe 1978). D. puncta ta eats seeds, fruits (Smythe 1978) and cotyledons of seedlings depending on the time of year (Emmons and Feer 1997). Seeds are nutrient rich, and D. punctata store them by way of caching behavior via scatter hoarding, which is essential for survival in t imes of scarcity (Smythe 1978). D. punctata is a rodent that survives on cached seeds when food is scarce, such as in the dry season, because it is not adept at storing nutrients as fat (Smythe 1978, Emmons and Feer 1997). A previous study found that the presence of Dasyprocta sp. greatly increases the probability of successful establishment of Hymenaea courbaril seeds and tree diversity (Asquith et al. 1999). It was concluded that the loss of scatter hoarding mammals like D. punctata will decrease fores t diversity and can lead to local extinctions in the presence of many seed predators. D. punctata therefore acts as both a predator and a disperser for trees. The purpose of this study was to find whether D. punctata maximizes its fitness by b ehaving as a density dependent forager. Additionally, the study aimed to discover whether the scatter hoarding caching behavior of D. punctata is aiding the fitness of Persea americana (Lauraceae), the cultivated avocado It was expected that there would be a positive correlation between the D. punctata foraging techniques and the density of seeds. Also D. punctata would disperse more seeds than they destroy, thus enhancing the fitness of P. americana. MATERIALS AND METHODS Study Site/Seed Preparation This study was conducted at the Santuario Ecolgico (formally Finca Ecolgica) located in Cerro Plano, Costa Rica, between October 28, 2005 and November 16, 2005 (Fig. 1a) for a total of five data days of data collection. A large sample of P. americana s eeds were collected from local
restaurants and bought from the super market. These seeds were used because Wittman (2005) found that the D. punctata showed a preference for P. americana. Seed exocarp was removed and cleaned with a towel if any remained o n the seed. The seeds were rinsed and allowed to dry fully. A one half meter piece of 50 mm diameter monofilament fishing line was passed through a small drilled hole in the top portion of each seed so as to not damage the embryo, and triple knotted. A piece of flagging tape was secured to the end opposite the seed. This technique of marking seeds was found not to influence the caching behavior of scatter hoarders in previous studies (Forget 1990), and has been found to have no effect on seedling viabil ity, germination or establishment (Forget 1993). Three different colors of flagging tape were used, corresponding to the three groups of seeds: A, B and C. Mock Tree A control tree that was not in the process of fruiting was chosen for a mock test in th e middle of the banana plantation (Fig. 1b). Two hundred meters away from the Santuario Ecolgico entrance, a circle of 50 meters in diameter around the control tree was cleared of any fallen seeds and fruits. The three colors of flagging tape corresponde d to the three distinct density rings. The closest ring to the tree, represented by letter A was the densest ring and contained 90 seeds randomly placed in a two meter ring around the tree. The second ring, represented by letter B, was the second densest ring with 40 randomly scattered seeds defined by a new ring two meters from the edge of ring A. The third ring, C, stretched two meters past ring B and contain ten seeds similarly scattered (Fig. 2). Seed Collection The seeds were set up at dawn and re collected the following day. Since the P. americana seeds were left out during night, and the Agouti paca (Rodentia, Dasyproctidae) is a nocturnal seed predator, any seed that got preyed upon by the A. paca was considered within the D. punctata predation (Reid 1997) Five different categories were observed for each seed corresponding to its ring: eaten, partially eaten, untouched, not recovered, and cached. Eaten seeds are seeds that were moved from their original ring and those which had 50% or more re moved by D. punctata thus affecting seed viability (Hopkins 1995). Partially eaten seeds are those that were moved from the original ring and may have been bitten but less than 50% was removed. Untouched seeds had not been altered in any way by the D. punctata and still remained in the original ring. Seeds that were not recovered consisted of lost seeds where the flag was found. Cached seeds were seeds that were buried under a substrate, earth or leaves, and were not damaged in any way. Qualitativ e observations of seed distance from parent tree, and caching depth were considered. Statistical Analysis A Chi squared test of independence was used to determine the foraging technique of D. punctata This test was used to compare touched seeds (eaten, partially eaten, and cached) to untouched seeds between the density groups. It was also used to compare the four fates of the seeds (eaten, partially eaten, cached and untouched) among their corresponding density groups. A two way ANOVA was used to dete rmine the fate of P. americana seeds. This test was used to make two comparisons; the different seed fates (eaten, partially eaten, cached, and untouched)
disregarding density groups, and the different seed fates (eaten, partially eaten, cached, and untou ched) for each specific density group. RESULTS A total of 700 seeds were presented to the D. punctata. Five hundred and seventy five were D. punctata out of all groups Touched seeds included seeds that the D. punctata had eaten or moved f rom their original ring. This included all seeds from the categories: eaten, partially eaten, not recovered, and cached. A total of 27 seeds were left in their original position. These seeds were disregarded by D. punctata and part of the category of un touched (Table 1). A Chi square test of independence (contingency table) between touched and untouched number of seeds found no statistical difference between the density groups A, B and C (p = 0.8651, Chi square = 0.2900, df = 2). No significant differ ences were found when comparing fates of the P. americana seeds (eaten, partially eaten, cached and untouched) and their corresponding density groups (A; B and C combined) (p = 0.3688, Chi square = 3.1520). Group B and C were combined to form one group be cause group C was too small for Stat View to run a contingency table. Since the data proved before that there was no significant difference between density groups, it is logical to say that combining group B and C would not alter the data. This is also p artly due to group C having a very small sample size in comparison with group A. D. punctata on average ate 5.8 6.3270 seeds, partially ate 5.2 5.4010 seeds, cached 15.267 15.7500 seeds, and untouched 1.8 2.9080 seeds for all density groups combi ned. (Fig. 3) The standard deviations are very large because the data are a combination of the different density groups. There is a wide range of data because of different sample sizes for each fate category of seed. D. punctata showed a preference tow ards caching seeds in time of abundance. A two way ANOVA found significant differences between the total number cached and eaten seeds (p = 0.0057, df = 1), cached and partially eaten seeds (p = 0.0034, df = 1), and cached and untouched seeds (p = 0.0010, df = 1). Splitting up the density groups, D. punctata on average, ate for groups A, B and C, 12.4 6.6560 seeds, 3.8 2.9500 seeds and 1.2 1.0950 seeds, respectively. D. punctata on average, partially ate for groups A, B and C, 10 5.6120 seeds, 5. 2 3.5640 seeds and .4 .5480 seeds, respectively. D. punctata on average, cached for groups A, B and C, 29.6 17.8970 seeds, 14.6 7.4700 seeds and 1.6 1.1400 seeds, respectively. D. punctata on average, untouched for groups A, B, and C, 3.8 4.3 240 seeds, 1.4 1.5170 seeds and 0.2 0.4470 seeds, respectively (Fig. 4). Again, the standard deviations are very large, but this is due to extreme differences between seed numbers for different data collection days. A two way ANOVA verified the findi ngs before, and found significance between cached and eaten seeds (p = 0.0002, df = 3), cached and partially eaten seeds (p < 0.0001, df = 3), and cached and untouched seeds (p < 0.0001, df = 3). It was observed that D. punctata had a finite limit to th e distance in moved P. americana seeds. In the field, no seed was found farther then 75 meters from the parent mock tree. Also, it was apparent that there was a positive relation between caching depth and size of seed.
______________________________________________________________________________ TABLE 1. The number of seeds that were touched and not touched for each density group and the totals, collected in November 2005 at the Santuario Ecolgico, Monteverde. Touched seeds consisted of recorded seeds that were eaten or moved from the original ring (Eaten, Partially eaten, Not Recovered and Cached). Untouched seeds were seeds disregarded by D. punctata (Untouched) (n = 700). _____________________________________________ _________________________________ Touched Seeds Not touched Seeds Group A 376 19 Group B 172 7 Group C 27 1 Total 575 27 DISCUSSION The purpose of this study was to determine if there was a positive correlation between the D. punctata foraging techniques and the density of seeds; also if D. punctata disperses more of P. americana seeds than they destroyed. This would result in D. punctata being a density dependent forager that increases the fitness of P. americana. The data suggest D. punctata does not forage based upon different densities. This result is evidence that D. punctata is a density independent forager because the density groups were distinctly different. Different fates of the seed having no difference between density g roups further proves that the D. punctata is a density independent forager in all of its ways of foraging. Density dependent and frequency dependent foraging are related because they both involve t rodents are not frequency dependent foragers (Hulme and Hunt 1999). Being a density independent forager shows that D. punctata does not forage efficiently. Since it is foraging randomly it is spending more energy in the process of seeking for food than it would be if foraging in a dense area (Herrera and Pellmyr 2002, Levey et al. 2002). In addition, this study does not discredit D. punctata as an exceptional forager. Only few seeds were left in their original position (Table 1), showing that D. punc tata is an optimal forager by taking advantage of the quantity of seeds through eating, partially eating and caching. One possible explanation for being a density independent forager is the quantity of seeds on the ground. The highest fruit production occu rs between September through January in Monteverde (Haber 2000). D. punctata is currently satiated with seeds, so it could be building up seeds in caches for the harsh dry season. The D. punctata is not adept at storing nutrients as fat, so its survival relies on the stored seeds in caches (Smythe 1978, Emmons and Feer 1997). Since there are many seeds, it is possible that it is foraging behavior involves gathering all possible seeds for future use, thus a density independent forager. The data suggest t hat D. punctata caches more P. americana seeds than it eats, partially eats and ignores (Fig. 3, Fig. 4). D. punctata may be increasing the fitness of P. americana by not only giving the seeds a substrate to grow in and protection from other seed predator s, but because of the vast numbers of seeds D. punctata is caching (Herrera and Pellmyr 2002). In French Guiana, 75 100 % of removed Carapa procera seeds were associated with scatter hoarding and secondary dispersal (Forget 1996). Many trees rely on scatter hoarders for survival. This reliance is based on chance of scatter hoarders not recovering the seeds due to
incomplete harvest (Herrera and Pellmyr 2002, Levey et al. 2002). Since such a large number of P. americana seeds were cached compared to other fates of the seed, some seeds will germinate resulting in an increase of fitness to P. americana. It would be advantageous of the P. americana to have a scattered seed rain because the seeds will get dispersed by D. punctata and avoid predation by d ensity dependent foragers. One possible explanation for D. punctata caching significantly more seeds then other foraging behaviors is due to the current season. It is currently the summer (wet season), and winter (dry season) is approaching rapidly. D. punctata is in need of many seeds to survive the harsh season, thus resulting in more cached seeds then preyed upon seeds (Herrera and Pellmyr 2002). Observations were made that there is a limitation to the distance that D. punctata caches the seeds of P americana. This is probably a method of caching so D. punctata can relocate the most seeds by concentrating searching in a specific area. Furthermore, it was also observed that bigger seeds were cached at deeper soil depths. Bigger seeds contain more n utrition, so it is advantageous of the D. punctata to invest more energy into the depth of caching. Since D. punctata will obtain more energy when the larger seed is exhumed, it would make sense to bury it deeper to avoid other predators. There is a dearth of density dependant foraging studies for rodents, and they need to be thoroughly studied to understand the density dependent foraging habits of D. punctata One possibility why this study did not find D. punctata to be a density depend ent forager was the concentric density rings offered to D. punctata might have been too close or not dense enough. D. punctata may have perceived all the rings as one dense area due to being so close, thus explaining why we found D. puncata to be a densit y independent forager. Many different quantities of P. americana seeds need to be observed and varied in distribution to see if D. punctata exhibits density dependence. Research needs to be long term and constantly studied throughout the year to see if s easonality has an influence on the caching behavior of D. punctata. This study does not take into account predation by A. paca, which could have greatly influenced the density dependent foraging results. If this experiment would be a principle study, it would have to separate seed predation by D. punctata and A. paca in the future since both are seed predators. Also, since P. americana is a cultivated fruit and does not occur naturally; it would be better to observe numerous fruiting trees in nature that the D. punctata prey upon. Studying various numbers of different trees will prove if this foraging technique is correct and widespread. It would make a more natural experiment, which is needed to understand the true foraging habits of D. punctata with t rees that it is accustom to feeding on. Vander Wall and Joyner (1998) found that that rodents re cache seeds numerous times, decreasing the quantity of seeds per cache with every move. To verify the concluded results about D. punctata increasing tree fit ness, sit is needed to study the moved caches and compare the final germination rate to the germination rate of P. americana in the absence of its scatter hoarding disperser. Optimal foraging amongst D. punctata also needs to be researched more thoroughly If D. puncata is an optimal forager, it will help understand the foraging behavior that it displays. The two observations of seed caching distance limitations and caching depth of seeds needs to be further studied to understand the true caching behavio r of D. punctata. ACKNOWLEDGEMENTS
I would first like to thank all of the restaurants for their gracious help in saving as many seeds as they did despite it not being the tourist season and to the Eco Farm for letting me do my research on their property. Thank you Alan for your hilarious a ntics and priceless face impressions. Thank you Karen for your support. Thank you Ollie and Maria for putting up with all of my ridiculous questions and constant pestering about being in the office. I would also like to say thanks to Toby and Mercedes for your help with the tedious process of constructing seeds to Javier for being a good advisor and letting me learn from my mistakes. This truly is a semester th at will never be forgotten. LITERATURE CITED Asquith, N.M., J. Terborgh, A. Elizabeth, and C.M. Riveros. 1999. The Fruits the agouti ate: Hymenaea courbaril seed fate when its disperser is absent. Journal of Tropical Ecology 15: 229 235. Emmons, L.H. and F. Feer. 1997. Neotropical rainforest Mammals, a field guide second edition. The University of Chicago Press, Chicago. Forget, P.M. 1990. Seed dispersal of Vouacapoua americana (Caesalpiniaceae) by caviomorph rodents in French Guiana. In D.J. Leve y, W.R. Silva, and M. Galetti (Eds). Seed dispersal and frugivory: ecology, evolution, and conservation, pp. 212. CABI Publishing, New York, New York. Forget, P.M. 1992. Seed removal and seed fate in Gustavia superba (Lecythidaceae). Biotropica 24: 408 4 14. Forget, P.M. 1993. Post dispersal predation and scatterhoarding of Dipteryx panamensis (Papilionaceae) seeds by rodents in Panama. Oecologia 94: 255 261. Forget, P.M. 1996. Removal of seeds of Carapa procera (Meliaceae ) by rodents and their fate in rainforest in French Guiana. In B.C. Wang and T.B. Smith. Closing the seed dispersal loop. Trends in Ecology and Evolution 17: 379 385. Herrera, C.M. and O. Pellmyr (Eds). 2002. Plant animal interactions, an evolutio nary approach. Blackwell Science Ltd., Oxford. Hopkins, W.G. 1995. Introduction to plant physiology. John Wiley and Son, Inc., New York. Hulme, P.E and M.K. Hunt. 1999. Variability in post dispersal seed predation in deciduous woodland: predator response to absolute and relative abundance of prey. In C.M. Herrera and O. Pellmyr (Eds). Plant animal interactions, an evolutionary approach. Blackwell Science Ltd., Oxford. Janzen, D. H. 1970. Herbivores and the number of tree species in tropical forests. The American Naturalist 104: 501 528. Levey, D.J., W.R. Silva, and M. Galetti (Eds). 2002. Seed dispersal and frugivory ecology, evolution, and conservation. CABI Publishing, New York, New York. Haber, W.A. 2000. Plants and vegetation. In N.M. Nadkarni and N .T Wheelwright (Eds). 2000. Monteverde: ecology and conservation of a tropical cloud forest. Oxford University Press, New York. Reid, F.A. 1997. A field guide to the mammals of Central America and Southeast Mexico. Oxford University Press, New York. Rh oades, D.F., and R.G. Cates. 1976. Toward a general theory of plant antiherbivore chemistry. In P. Coley. Herbivory and defensive characteristics of tree species in a lowland tropical forest. Ecological Monographs. 53: 209 234. Smythe, N. 1978. The natu ral history of the Central American agouti ( Dasyprocta punctata ). In D.J. Levey, W.R. Silva, and M. Galetti (Eds). Seed dispersal and frugivory: ecology, evolution, and conservation, pp. 212. CABI Publishing, New York, New York. Smythe, N. 1978. The natu ral history of the Central American agouti ( Dasyprocta punctata ). In D. H. Janzen (Ed). Costa Rican Natural History, pp. 463 465. University of Chicago Press, Chicago. Vander Wall, S.B. and J.W. Joyner. 1998. Recaching of Jeffrey pine ( Pinus jeffreyi ) se eds by yellow pine
chipmunks ( Tamaias amoenus) : potential effects on plant reproductive success. In B.C. Wang and T.B. Smith. Closing the seed dispersal loop. Trends in Ecology and Evolution 17: 379 385. Wittman, E. 2005. Preference on the scatter hoarding behavior of the Central American agouti ( Dasyprocta punctata ). CIEE Monteverde Spring 2005, Tropical Ecology and Conservation. pp. 220 231.
______________________________________________________________________________ FIGURE 1a. Map of the Monteverde region of Costa Rica. The study site indicated by a red box, was located at the Santuario Ecolgico in Cerro Plano, Costa Rica in November 2005. ______________________________________________________________________________
______________________________________________________________________________ FIGURE 1b. Map of the trails that comprise the Santuario Ecolgico. The study site indicated by the red arrow was located 200 meters in the direction of the picnic tables away from the entrance house in the banana plantation. Cerro Plano, Costa Rica, November 2005. ______________________________________________________________________________ ___________________________________________________________________________ FIGURE 2. The mock tree in which the experiment occurred at the Santuario Ecolgico was comprised of concentric rings that were two meters in width. The densest ring, A, was centered around the tree and contained 90 random scattered seeds. Ring B, the intermedia te dense ring contained 40 random scattered seeds. The least dense and farthest ring from the tree contained ten random scattered seeds. Cerro Plano, Costa Rica, November 2005. ______________________________________________________________________________