Monteverde Institute: Tropical Ecology and Conservation

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  Communal care of offspring in the white-faced capuchin monkey (Cebus capucinus), May 2005

  Kristin A. Hook

  The purpose of this study was to document whether a communal infant care system existed in the whitefaced capuchin monkey, Cebus capucinus (Cebidae), in the Monteverde area. The intention was to draw comparisons in time allocation spent between infants and other individuals in the troops followed. In addition, approach and leave times in interactions involving the infant and other members of the troop as well as the sexes of those individuals involved were documented. It was found that a communal infant care system does in fact seem to exist for this species of primate. Infants spent the majority of their time on the backs of a primary female in addition to the backs of juveniles. The majority of approaches made were to engage in social interaction. The majority of approaches made by individuals other than the primary female were either solicitations or offers for rides. There was no difference in numbers of approaches initiated by female or male individuals; however, females spent more time involved with the infant during their interactions than did the males.

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  Distribution and abundance of Epidendrum parkinsonianum (Orchidaceae) in relation to habitat and microhabitat type, May 2005

  Alyson Mohan-Lucas

  Orchid distribution and abundance are likely functions of both abiotic and biotic factors. Forty host trees were surveyed, 20 in a closed forest site and 20 in an open area, in Monteverde, Costa Rica. The distribution and abundance of Epidendrum parkinsonianum were examined in order to better understand how they are spatially distributed across habitats and microhabitats, and to suggest possible explanations for this distribution. Epidendrum parkinsonianum was significantly more common in the open area than the closed forest, with more orchids found per tree. Trees were divided into five tree zones to compare the distribution of orchids along abiotic gradients within microhabitats. Epidendrum parkinsonianum followed a random distribution in the open site, however in the closed site there were more orchids than expected in zone two and less than expected in zone four. In addition a significant correlation was found between the percent occupied by other vascular epiphytes and the E. parkinsonianum. Further investigation needs to be done in order to better understand exactly which factors are affecting the distribution and to what degree.

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  Dung and soil type as factors for niche partitioning in dung beetles (Scarabaeidae), May 2005

  Sasha Hays

  The Competitive Exclusion Principle proposes that each species fulfills a unique niche, yet dung beetles are an extremely diverse taxon and subsist upon a very limited resource. Dung beetles were caught in a Monteverde, Costa Rica, cloud forest in traps that varied in soil and dung type, to examine how these species partition niches. Additionally, four species of dung beetles were subjected to dung and soil choice experiments in a laboratory. There was a significant relationship between dung type and diversity in the traps. One species, Deltochilum mexicanum, showed significant preferences for soil and dung across both field and laboratory studies, but did not show its soil preference in the presence of a competitor, Ontherus propracellens/O.incensus. Overall, trap communities were significantly less similar, perhaps due to the difference in abiotic factors, particularly dung and soil type.

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  Effects of detritus abundance and diversity on the composition of detritivore communities within tank bromeliads, May 2005

  Callie Brown

  Detritivores are important in the cycling of nutrients within bromeliads as they help release nutrients from detritus, making them available to the plant. This study set out to explore how the amount and diversity of detritus influenced the detritivore community structure within bromeliads. Results indicated that a greater amount of detritus supported a greater number of detritivore individuals and by some indices, a richer detritivore community. However, detritus diversity appeared to have no significant effect on the richness or abundance of detritivores. This could indicate that detritus is in fact a homogeneous resource and resource partitioning is not occurring among detritivores. It is also possible that detritivores are partitioning detritus according to factors other than the detritus source material, which was the factor considered in this study.

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  Factors influencing pollination and fruit set in Epidendrum radicans, May 2005

  Megan Dixon

  Food deception mimicry is a device in which plants lure pollinators with flowers that don’t contain a reward. Flowers that use deception may use two taxa mimicry, automimicry, or mimicry based on naivete. Epidendrum radicans has been documented to take advantage of two taxa mimicry only in close geographic range. This study finds that although pollinia removal and pollination is low in monospecific patches of E. radicans, successful pollination is a product of pollinator naivete and/or long distance two taxa mimicry. The likelihood of pollinator visitation increases for each plant with inflorescence size. Pollination rate peaks with the peak in migrating populations of naïve butterflies. With low rates of pollination, it is highly likely that thriving populations rely heavily on vegetative reproduction. In the case of pollination, pollinia removal leads the plant to drop its flower early. I hypothesize that this mechanism promotes genetic diversity within the population.

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  Foliar changes in Saurauia montana along an altitudinal and soil fertility gradient, May 2005

  Miles T. Gray

  Despite high productivity, tropical forests are found on soils with low soil fertility. The creation of new biomass requires nutrients, so trees on these soils are more efficient at using and cycling nutrients. Tropical soils have been found to show soil fertility gradients in relation to annual precipitation, seasonality, age, and altitude. While tropical ecosystems and single temperate trees have been shown to respond to soil fertility gradients, similar studies of tropical trees are sparse. Here, I study a single species of tropical tree, Saurauia montana, from 1530 to 1785 m, to find changes in leaf toughness, specific leaf area, and foliar phosphorous levels. I found a slight decrease in phosphorous levels with altitude along with slight decreases in calcium, magnesium, potassium, iron, and nitrogen. S. montana leaves differed altitudinally with increased toughness, decreased specific leaf area, and decreased leaflitter phosphorous levels with increasing altitude. Corresponding changes in decomposition rates of leaves along the gradient were not found. Leaflitter levels suggest that retranslocation occurs more at higher altitudes, but calculated retranslocation values showed no trend. With altitude, the leaf toughness increased, the specific leaf area decreased, and leaflitter phosphorous levels decreased, but none of these changes was shown to be directly related to soil phosphorous levels. So, the foliar changes in S. montana may be related to another environmental factor that varies with altitude.

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  Forest regeneration in Rosellinia infected areas of Los Llanos, Monteverde, and possible biocontrol agents, May 2005

  Jessica Smith

  A fast-spreading fungus in the genus Rosellinia threatens the forest composing the Monteverde Corridor in Los Llanos area. This fungus spreads through the soil and has been observed to kill both adult and juvenile trees. The intent of this study was to learn more about the effects of Rosellinia in the forest with the ultimate goal of creating a biocontol. The experiments consisted of four parts: seed germination of pioneer and canopy tree species, sapling infection rates of pioneer and canopy tree species, evaluation of the understory composition of the infected area in comparison to a pristine, and previous tree composition data, and the investigation of the presence of another fungus from the genus Trichoderma that may serve as a natural predator of Rosellinia. Overall, the fungus was found to be a general root specialist. Of the two genera evaluated as possible biocontrols, Bocconia was found to have effects on the germination of Ocotea whitei seeds in infected soil; however, these effects did not extend to Citharexylum costaricensis seeds. The absence of Trichoderma from the soil does not seem to be the reason Rosellinia established, nor does it look promising as a biological control without the introduction of an exotic species. Evaluation of the regenerating plant community in the infected area indicated that Rosellinia has not yet affected the seed bank. This fact gives hope for the future in that if a biological control can be found, the forest should be able to regenerate to a pristine condition.

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  Functional differences among color morphs of Impatiens walleriana (Balsaminaceae), May 2005

  Anne B. Morris

  Functional differences between color morphs of Impatiens walleriana were studied in Monteverde, Costa Rica to see if they influenced the fitness of the color morphs. Nectar removal rates, nectar quantity, nectar quality, length of pollen availability, flower longevity, and seed set were compared between magenta, salmon, pink, and white color morphs. Red, purple, magenta, pink, salmon, and white cultivated Impatiens and magenta, salmon, pink, and peach I. walleriana were observed in the Monteverde Butterfly Garden to see if color preferences occur among butterflies. In addition, magenta color morphs were studied along an altitudinal gradient to see if altitude caused functional differences within a single color morph and to see if instances of nectar robbery varied on an altitudinal scale. Among I. walleriana color morphs nectar removal rates were found to be affected by nectar robbery, all morphs suffered equally from nectar robbery. Color morphs also produced similar quantities of nectar. Magenta and salmon morphs produced nectar with higher sucrose concentrations than pink and white morphs. Color morphs did not exhibit differences in the length of pollen availability, but pink and white flowers were found to live longer than magenta and salmon flowers. In terms of seed set, all flowers were found to have high occurrences of seed set despite differences in nectar removal, robbery, and quality and in flower longevity among morphs. When cultivated Impatiens were observed for removal rates, pink and white had the most nectar removed. Heliconiinae butterflies showed species specific color preferences to the cultivated Impatiens. Eueides isabella preferred pink, white and salmon colors. Heliconius hecale preferred pink and magenta flowers. Dryas iulia preferred white and salmon colors and Heliconius charitonius preferred the colors pink and salmon. When I. walleriana color morphs were observed in the butterfly garden, salmon was the morph with the least nectar removed. Two Heliconiinae butterflies showed specific color preferences to I. walleriana. Eueides isabella disliked the color salmon. Heliconius hecale preferred salmon and peach. Although, Dryas iulia and Heliconius charitonius also visited I. walleriana they did not demonstrate specific color preferences. In addition, magenta color morphs were observed in San Luis (1105 m), on la Trocha (1305 m), and in Montverde (1535 m). A significant difference was found between nectar removal in San Luis and la Trocha; this may have been due to nectar robbery, which only occurred in San Luis. Differences in pollen availability were also found between the three sites. Along the gradient, almost all flowers set seed. Differences in color (nectar removal), nectar concentration, flower longevity, length of pollen availability, and nectar robbery cannot explain the high occurrence of seed set in all flowers; therefore, I. walleriana color morphs have similar fitness. It is likely that most flowers are being pollinated, and thus set seed, due to the presence of many different pollinators whose preferences encompass all the color morphs.

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  Herbivore-induced defenses in Passiflora biflora, May 2005

  Melissa Morris

  Herbivore-induced defenses in plants save energy in the absence of herbivory (Karban et al. 1997). Despite this, Passiflora biflora has not been shown to have short-term induced defenses in past studies (Baptiste 2002). P. biflora might have a slower reaction to chronic herbivory either through greater leaf toughness or greater cyanide concentrations. To test this, leaves from three sites were assessed for herbivory defense. The first two sites were butterfly gardens with high and low populations of butterflies from the genus Heliconius, for whom Passiflora vines are the host plant. Defense levels were compared with nearby plants outside the garden at a third site. Light intensity, percent herbivory, leaf toughness, and cyanide were measured at each site to quantify herbivory defense. Light intensity was significantly higher in the garden with lower Heliconius populations (p=0.0086). Herbivory, measured by number of caterpillars encountered, was significantly higher in the garden with high Heliconius density. Leaf toughness was significantly lower at the roadside site (p=0.0231), but similar for the two butterfly gardens. Cyanide concentrations were significantly lower in the garden with fewer Heliconius, compared to the other two sites (p=0.002). While the cyanide concentration for vines outside the garden was higher, low leaf toughness there indicates younger vines, which are reported to have higher cyanide content (Magee 1995). Both gardens had similar leaf toughness, indicating similar age, yet significant differences in cyanide content. This implies that at higher and chronic levels of herbivory, Passiflora biflora shows induced defenses to herbivory.

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  Impact of tourism on bird diversity, abundance, and community composition, May 2005

  Micah Scholer

  In recent years the ecotourism industry has been touted as offering incentives for protecting biodiversity while promoting economic growth for the surrounding communities. This paper examines the impact that ecotourism has on bird communities in the Monteverde Cloud Forest Preserve. Abundance and species richness for birds were compared on tourist trails and trails closed to tourist. The results indicated no significant difference in H’ values between trail types. The average species richness between trail types was not significantly different, but tourist trails significantly increased in average abundance. Increases may be a result of food resources provided by the Preserve on tourist trails or to a decrease in predation on such trails. Sustainable tourism requires an awareness of the pitfalls of tourism and requires efforts to minimize the impact visitors have on the environment.

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  Importance of volcanic ash deposits in the soil horizon of the Monteverde cloud forest, May 2005

  Jesse Robinson

  Soils derived from volcanic activity are some of the most productive in the world, and the tropical Andisols of Monteverde, Costa Rica are no exception. This study is a general analysis of the importance of one aspect of volcanic activity, historic ash deposition, found in visible, differentiated soil horizons throughout the lower-montane cloud forest ecosystem of Monteverde. This analysis was performed with three separate experiments to explain two hypotheses: (1) The use of volcanic ash in existing root systems, and (2) the importance of historic ash deposit exposure through landslides. Soil was sampled in exposed profiles in six separate sites. Phosphorus and Nitrate nutrient levels were tested at defined points in the soil profile: AHorizon (organic layer), Upper B Horizon, and the ash layer. Soil samples from site two were sent to the Ministry of Agriculture (MAG) for additional nutrient analysis. Germination rate and success of Phytolacca rivinoides, a gap colonizing species, was tested for soil samples from three differentiated horizons (A, B-Upper and Ash) from each site. Finally, root penetration throughout the soil profile was measured. Results for nutrient tests indicate no difference between soil horizons (Friedman rank-sum, p = 1) indicating that the ash layer is not an important reservoir of Phosphorus and Nitrate. Seed germination success was limited (<1%) and no further analysis was possible. Root penetration for the only tested profile shows an increase of dry-weight in the profile surrounding the volcanic ash horizon. Other nutrients or untested properties of this horizon may be a useful source to roots, and possibly important in other biotic ways. Results suggest that ash layers are not a reservoir for limiting nutrients, but may enhance root development through texture or unmeasured nutrients.

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  Lichen richness along an air pollution gradient in Monteverde, Costa Rica, May 2005

  Jennifer M. Toy

  Lichens have a long history of being used to indicate and monitor air pollution because of their extreme sensitivity to air and water pollutants. However, knowledge about their effectiveness as bioindicators in the tropics is limited. The purpose of this study was to determine the effects of air pollution on lichen species richness and abundance as a function of: 1) orientation, or the side of the tree facing the road (front side) versus the side of the tree facing away (backside) from the road, 2) position, or where the tree is located in relation to the road and other surveyed trees, 3) absolute distance from the road, and 4) host diameter breast high (DBH). Nine sites were established, each with a transect of five Cupressus sempervirens trees moving perpendicularly away from heavily trafficked roads in Monteverde, Costa Rica. For each host tree (n = 45), the host DBH, absolute distance, and position were measured and the lichen community richness and the percent of the host bark covered were estimated. A multiple regression revealed a relationship between tree size and cover (p = 0.041). Friedman tests revealed that lichen species richness and abundance increased as a function of position along transects up to the fourth tree from the road. Wilcoxon sign-rank tests revealed that the number of times the back side of trees closest (in terms of position) to the road had a greater lichen abundance was significantly higher than the front side of the same trees.

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  Litter depth, soil moisture, stem and seed counts around trees on slopes in a premontane tropical moist forest, May 2005

  Sarah Schramm

  Leaf litter maintains soil moisture (Kohnke and Franzmeier 1995), potentially enhances seed capture, and provides nutrients such as nitrogen (Foth 1970; Orndoff and Lang 1987), all three of which are important in seed germination and recruitment (Hopkins 1993; Harms et al. 2000). It was expected that areas of litter capture (tree bases on slopes) would have greater seedling recruitment as a result of the environmental conditions enhanced by leaf litter. This study was conducted in the Monteverde cloud forest, a premontane tropical moist forest in Costa Rica, during the end of the dry season (April-May). Twenty trees with a mean diameter of 28.7 cm (SD = +/- 4.6 cm) were selected and a circular plot extended 60 cm from the tree surface, which was divided into upslope and downslope halves. The number of stems, litter depth, soil moisture, and number of seeds were measured in each half, and the differences between the values were averaged. There was no significant difference found between upslope and downslope values for each variable (stems, moisture, and seeds all had the first SD overlap zero, litter depth p = 0.36 in paired t-test). Additionally, there was no significant difference in stem number (upslope-down) as a function of slope (p = 0.78, regression analysis). This may be due to the overlap of upslope and downslope conditions of different trees, causing litter capture to be evenly distributed or, alternatively, leaf litter in this environment may inhibit seedling recruitment by reducing oxygen and light.

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  Niche partitioning by frugivorous bats in the San Luis Valley, Costa Rica, May 2005

  Rachel M. Johnson

  Niche partitioning is an important form of ecological differentiation that allows two or more species to coexist. It has also been shown to be responsible for maintaining the vast diversity of bat species found in the tropics (Aguirre et al. 2002). A community of frugivorous bats in the San Luis Valley, Costa Rica, was sampled to determine the parameters of niche differentiation used by the bats. The study took place at the San Luis Ecolodge at 1100 meters in elevation in premontane wet secondary forest. Bats were mist netted using two 12-meter mist nets over seven nights in the month of April, 2005. Time of capture, forearm measurements and weights were recorded and fecal samples were collected. Seeds present in the samples were identified to species to determine if the bats were differentiating niches based on species of plant consumed. There was no niche partitioning due to plant species, but statistical significance was found when time of foraging and the size of the bat compared to the species of fruit eaten were analyzed. It was determined that the species were differentiating niches based on fruit size and time of foraging.

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  Palm epiphylls response to elevation and mist frequency in a Costa Rican cloud forest: A possible bioindicator of local climate change, May 2005

  John E. Drake

  Recent extinctions coupled with climate changes in montane cloud forests of Costa Rica have highlighted the need to understand the biological consequences of local drying and decreased mist frequency in these ecosystems. With the intent of identifying a bioindicator of mist frequency, I performed an altitudinal transect of epiphyll cover on Geonoma fronds and an experimental manipulation of mist conditions on epiphylls of Chamaedorea fronds. Epiphyll cover on Geonoma was found to increase linearly with elevation (p < 0.0001). Percent cover of epiphylls did not respond to added mist, but the variation in epiphyll cover increased significantly with experimentally added mist (F-test, p <0.05). The ratio of liverworts to lichens was high in dry conditions and low in conditions of experimentally added mist. This ratio shows promise as a bioindicator of mist conditions in tropical montane cloud forests.

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  Pollinator limitation and seed set of Impatiens walleriana, May 2005

  Alison Parker

  Plants that are pollinator limited may show important fitness relationships with factors influencing visitation. Groups of 60 bagged, natural, and hand-pollinated flowers of Impatiens walleriana (Balsaminaceae) showed much higher seed set with pollination - flowers produced seed pods 21%, 70%, and 100% of the time, respectively. I also found higher seed set for high visitation sites in the Monteverde Butterfly Garden with naturally visited patches outside – mean seed set inside was 146.5 per 60 stems, while outside it was only 81. Neighborhood, patch size, sunlight, and elevation are speculated to play a role in pollinator visitation. I compared seed set of these variables among patches throughout Monteverde, Costa Rica. With a mean of 81 seed pods per 60 stems, patches located in the vicinity of other flowering plants have a significantly higher seed set than isolated patches, with a mean of 55.6 seed pods per 60 stems. There is a slight tendency for seed set to increase with patch size, but this relationship is not significant. Flowers located in higher sunlight produced significantly more seed pods than those in the shade with means of 5.6 and 2.4 pods per 5 stems, respectively. Finally, seed set increases along an altitudinal gradient. It appears that I. walleriana is pollinator limited and that nearby flowers of other species, higher sunlight and higher elevation increase the likelihood of seed set through greater visitation.

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  Preference on the scatter-hoarding behavior of the Central American Agouti (Dasyprocta punctata), May 2005

  Emily Christine Wittman

  Dasyprocta punctata is a scatter hoarding rodent commonly found in the lowland rainforests of Costa Rica. Its method of seed dispersal consists of carrying seeds from the ground below trees and storing each individual seed in small caches for consumption in times of food scarcity (Jansen et al. 2002). For this reason, D. punctata plays an important role in seedling recruitment and forest composition (Herrera and Pellmyr 2002). The purpose of this study was to determine the role preference played on the scatterhoarding behavior of D. punctata. Three species of seeds (Panopsis suaveolens, Persea americana, and Inga punctata) were offered at the Finca Ecológica in the Monteverde region of Costa Rica to observe the role of preference. A total of 420 seeds were presented to D. punctata at the site over a two-week period; data were collected on what behaviors were performed on the seeds. Results showed significant preference for different behavior treatments of seeds (Chi- squared = 7.11, p = 0.05), in addition to significant preference for caching seeds in different microhabitats (Chi – squared = 26.3, p = 0.05).

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  Presence of protozoan parasite Ophryocystis elektroscirrha (Neogregarinda: Ophryocystidae) in populations of butterflies in Monteverde, Costa Rica, May 2005

  Jess Singleton

  Ophryocystis elektroschirrha (Neogregarinda: Ophryocystidae), is a parasite found in populations of monarch (Danaus plexippus) and queen (Danuas gilippus) butterflies (Lepidoptera Nymphalidae Danainae) (Altizer & Oberhauser 1997, Altizer et al. 2000, Leong et al. 1997, Vickerman et al. 1999). The parasite has both asexual and sexual stages in its lifecycle, and produces spores while the butterfly is pupating (Yixian Yueh 2005). Larvae become infected when they consume leaves or egg shells contaminated with spores. High densities of spores restrict body size and can reduce fecundity and life span in male adults (Altizer & Oberhauser 1999). This study investigates whether the parasite occurs on other species of butterflies. One hundred and fifty-two butterflies were caught in Monteverde, Costa Rica, and sampled for spores. A one cm squared piece of transparent sticky tape was pressed against the abdomen, and then adhered to a microscope slide. Slides were examined under 40 X magnification, and all spores were counted. The butterflies represented the families Pieridae and Papilionidae and also seven sub-families of Nymphalidae: Charaxinae, Danainae, Ithomiinae, Melitaeinae, Nymphalinae and Morphinae. Five individuals were infected, all D. plexippus. The spore counts ranged between 590 and more than 1000 per square centimetre. These intensities were much higher than in a previous study in the Monteverde region which found only seven and three spores on two monarch butterflies (Hsu 2004). The absence of the parasite in the other families and sub-families sampled may be due to inadequate sample sizes, or alternatively may be explained if the parasite host relationship is an obligate one. Future studies could more extensively research the occurrence of O. elektroscirrha in monarch and queen populations in Monteverde. It would also be worthwhile to focus on Danaine and Ithomiine butterflies closely related to D. plexippus and D. gilippus in case phylogenetic relatedness controls susceptibility to infection.

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  Protist community diversity in relation to resources in bromeliads, May 2005

  Jessica Spaulding

  Protists are microscopic organisms which play an important role in nutrient degradation in tank bromeliads (Carrias et al 2001). Their diverse communities provide good subjects of study on community assembly and their existence in bromeliads make them a unique, yet accessible case study. Resource based models suggest that an increase in resources leads to an increase in biodiversity. Since no two species can occupy the same niche, increased resources can lead to niche differentiation, promoting community diversity (Osborne 2000). This study hypothesized that as the amount of light, area, water, and food sources increase in a bromeliad community, the diversity of protists will also increase. Data were collected among 48 bromeliads at the Ecolodge San Luis (1100 m), Monteverde, Costa Rica, at the end of dry season, between April 20 and May 5, 2005. Shannon Weiner indices (H’, N, S, and E) were calculated and analyzed against the four resources (light, area, water, and food source) using a multiple regression. The results of the multiple regression showed that an increase in these resources had no significant effect on protist diversity in bromeliads (p values > 0.05). This study indicates that there may have been other factors influencing protist diversity in bromeliads. An increase in resource diversity may have effects on protist diversity, but further study is needed.

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  The impact of avian diversity on insect herbivory in shade and sun coffee plantations, May 2005

  Christina Wong

  In the last 20 years Central American coffee production has drastically increased causing many farmers to accept and utilize monospecific stands, and either reduce or completely eliminate shade trees from coffee plantations. This study examined how a range of different shade and sun plantations affect avian diversity, and the role of avian insectivores on arthropod coffee herbivory. Avian diversity was studied at four sites: simple sun, complex sun, simple shade and complex shade. Avian insectivorous activity was measured from distinct peck-marks on non-toxic artificial caterpillars. Shannon-Weiner diversity indices found species diversity to be highest in complex shade (H’ = 3.34) and lowest in simple sun (H’= 2.27). However, avian diversity in simple shade (H’ =2.83) was not significantly greater than the complex sun (H’ =2.78). Shade coffee also possessed higher arthropod and avian insectivore abundances, but experienced significantly less herbivory and received significantly greater number of caterpillar peck-marks than the sun coffee. My results suggest that a coffee plantation’s vegetative characteristics and structure greatly affects avian diversity and high abundances of avian insectivores can potentially control arthropod herbivory.

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  Trail width and epiphyllous coverage of Chamaedorea spp, May 2005

  Jamie Hallen

  Epiphylls are bryophytes and lichens that grow on the leaves of other trees. These plants are dependent on water for survival and reproduction. Lichens are often used as bioindicators of climate change and pollution. The purpose of this study was to find out if trail width sufficiently changed the microclimate and altered epiphyll cover on trailside leaves. I hypothesized that epiphylls could be used as bioindicators of changing microclimate by trails from a control area. Liverwort and lichen cover were measured on leaves of Chamaedorea spp. (Arecaceae) in the Monteverde Biological Cloud Forest Preserve on five different trail types. Wider trails had decreased epiphyllous growth compared to narrower trails, with reductions of 82% to 89% on wide trails and 28% reductions on narrow trails. Epiphylls have shown that they can be used as bioindicators of small changes in sunlight due to trail widths. Epiphyll cover is declining linearly with trail widths. These effects can be warning signs for others plants that are harder to examine effects on.

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  Importance of green receptivity in Euglossa tridentata (Hymenoptera: Apidae) foraging behavior, March 2005

  Philip J. Kranzusch

  This study experimentally tests the visual discrimination ability of Euglossa tridentata with three colored mazes. A black and white maze represented total contrast, and served as a null model to compare the ability of E. tridentata to distinguish colors in a green and white maze, and a maze designed after the orchid Sobralia lindleyana. Test bees behaved as predicted in the Green-White maze where the mean completion time was significantly longer than each other maze. This indicates Hymenopteran green photoreceptors are relatively insensitive in foraging. Although the null model was predicted to be the easiest color combination to distinguish, the maze based on S. lindleyana’s floral colors had a significantly shorter mean completion time. This suggests that bee vision has evolved to distinguish color sets that indicate the location of resources, and not optimal vision to be able to discriminate between all colors and patterns. The experimental data support “Exaptation Theory” as the most valid model describing the role of green receptivity in Hymenopteran foraging behavior.

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  Sex ratios of Ithomiinae visitation to Ageratum reedii as a source of pyrrolizidine alkaloids, March 2005

  Mary Dain

  People in developing countries have traditionally used forests as sources of local, cheap medicines. One plant used throughout the Neotropics is Cecropia spp., most notably for asthma. The purpose of this study was to determine if tea made from Cecropia obtusifolia leaves increases lung capacity and in what time frame this takes place. This was accomplished by treating a group of people with Cecropia tea for five days and another group with a placebo treatment and comparing the change in lung capacity of the two. The short term change in the placebo group had a statistically insignificant decrease of 2% while the Cecropia showed a significant increase of 4%. This indicates that C. obtusifolia leaves do in fact contain medicinal chemical properties. Hence, while further clinical test should be performed, Cecropia provides a good example of the importance of local plants and their conservation for human health.

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  Anthropogenic impacts upon neotropical mammal communities, November 2004

  Holle Harjer

  Human fragmentation of tropical rainforests greatly affects animal populations and ecosystem composition. In this study the effects of fragmented secondary forests upon mammal diversity and species richness and continuous secondary forests were examined. Track records and visual observations were made for three habitats including the interior secondary forest, forest edge and disturbed areas. Results showed a higher diversity in the more connected Monteverde habitats than in the fragmented San Luis area. Greatest diversity was exhibited in forest edge habitats for both Monteverde (H = 2.71) and San Luis (H = 1.91). Species overlap and community similarity was also greater in the Monteverde region (Cs > 0.60).