Monteverde Institute: Tropical Ecology and Conservation

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  Sugar concentrations, hummingbird aggressiveness, and community composition in Monteverde, Costa Rica, August 2006

  Paul Brooks and Jennifer M. Gillen

  We studied hummingbird communities in Cañitas, Monteverde, Puntarenas, Costa Rica to observe territorial tendencies when given high and low percentage sugar concentration of food resources at artificial feeders along the edge of a forest patch. We wanted to determine if community composition was disproportionately affected by more aggressive, and therefore territorial species. We observed interactions of hummingbirds at artificial feeders of 20 and 33% sugar concentration. We found a disproportionately high number of visits by Rufous-tailed Hummingbirds (Amazilia tzacatl) at both sets of feeders (52.5% at 20% feeders and 89.4% at 33% feeders). We found a higher frequency of visits by all species at low reward feeder than at the high reward feeder (1016 visits at 20% feeders and 716 at 33% feeders) and a higher proportion of aggressive interactions at the lower reward feeder. Rufous-tailed hummingbirds were the most territorial species at our study site and their behavior influenced the relative abundance of subordinate species. Contrary to what we expected, we found that frequency of close chases and far chases at different sugar concentration feeders were not different than random.

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  Tremella sp. data sheet: Tremella sp. [images], August 2006

  Jason Prior and Matthew Prior

  Specimen data sheet and accompanying images of Tremella sp.

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  Tricholomataceae [sp.] #2 data sheet: Tricholomataceae [sp.] #2 [images], August 2006

  Jason Prior and Matthew Prior

  Specimen data sheet and accompanying images of Tricholomataceae [sp.] #2 in a macrofungal abundance and distribution study done during the wet season in Monteverde, Costa Rica.

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  Tricholomataceae [sp.] #3 data sheet: Tricholomataceae [sp.] #3 [images], August 2006

  Jason Prior and Matthew Prior

  Specimen data sheet and accompanying images of Tricholomataceae [sp.] #3 in a macrofungal abundance and distribution study done during the wet season in Monteverde, Costa Rica.

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  Tricholomataceae [sp.] #4 data sheet: Tricholomataceae [sp.]#4 [images], August 2006

  Jason Prior and Matthew Prior

  Specimen data sheet and accompanying images of Tricholomataceae [sp.] #4 in a macrofungal abundance and distribution study done during the wet season in Monteverde, Costa Rica.

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  Tricholomataceae [sp.] #5 data sheet: Tricholomataceae [sp.] #5 [images], August 2006

  Jason Prior and Matthew Prior

  Specimen data sheet and accompanying images of Tricholomataceae [sp.] #5 in a macrofungal abundance and distribution study done during the wet season in Monteverde, Costa Rica.

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  Tricholomataceae [sp.] #6 data sheet: Tricholomataceae [sp.] #6 [images], August 2006

  Jason Prior and Matthew Prior

  Specimen data sheet and accompanying images of Tricholomataceae [sp.] #6 in a macrofungal abundance and distribution study done during the wet season in Monteverde, Costa Rica.

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  Tricholomataceae [sp.] #7 data sheet: Tricholomataceae [sp.] #7 [images], August 2006

  Jason Prior and Matthew Prior

  Specimen data sheet and accompanying images of Tricholomataceae [sp.] #7 in a macrofungal abundance and distribution study done during the wet season in Monteverde, Costa Rica.

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  Tricholomataceae [sp.] #8 data sheet: Tricholomataceae [sp.] #8 [images], August 2006

  Jason Prior and Matthew Prior

  Specimen data sheet and accompanying images of Tricholomataceae [sp.] #8 in a macrofungal abundance and distribution study done during the wet season in Monteverde, Costa Rica.

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  Water quality in the Quebrada Máquina: heavy metal, fecal coliform, chloride and sulfide Levels, August 2006

  Rachel Johnson, Jessica McElfresh, and Laura Sawatzke

  The purpose of this study is to determine if concentrations of heavy metals, sulfide, chloride and fecal coliforms vary based on relative location to commercial and domestic waste sources along the Quebrada Máquina in Monteverde. Assessments were performed at stream and road run-off sites near Hotel Belmar, CPI Language School, the Monteverde gas station, and below a main road. In addition, three pristine forest stream sites were assessed as controls for a basis of comparison. Chromium-hexavalent, chloride, copper, iron and sulfide levels were tested at each of the seven sites. No significant difference was observed for any heavy metals tested, or for chloride or sulfide. However, higher levels of copper and iron were observed at the gas station and road run-off sites. These sites were exposed to the highest levels of commercial waste, which may account for the trends observed. One water sample was analyzed for the presence of arsenic, mercury and lead from the off-road site and upper-most forest site. Concentrations were identical at both sites for all three metals and were well below toxicity levels. Coliform levels were tested at the pristine forest site and near a lower site exposed to domestic activity. There was a significant difference in the levels of coliforms between the two sites (p < 0.0001). The low levels observed at the pristine forest site were most likely due to animal feces and plant run-off, while the extremely high levels observed at the lower CPI site were likely indicative of improper disposal of domestic sewage.

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  Clavaria sp. data sheet: Clavaria sp. [images], July 18, 2006

  Jason Prior and Matthew Prior

  Specimen data sheet and accompanying images of Clavaria sp.

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  Density-dependent parasitism in Centropogon solanifolius (Campanulaceae) and changes in floral and sex-phase longevity following infestation, July 15, 2006

  Erik Z. Solberg

  Centropogon solanifolius flowers (Campanulaceae) are parasitized by the fly larvae of Zygothrica neolinea (Drosophilidae). The larvae burrow into the anther of the developing flower bud and eat the pollen, which changes the longevity dynamics among the infested, protandrous flowers. This study investigated whether the flies were parasitizing in a density dependent manner. The study also explored strategies that flowers used to cope with the high infestation rates (!50% in a previous study and documented here as well). To find answers to these questions, 83 flowers were located, their infestation status noted, and nearest neighbor distance measured. Additionally, 78 other flowers were bagged and tagged to look for changes in overall flower lifetime, as well as the longevities of the male and female phases. The results show that group dependence parasitism is operating, with 33% more grouped flowers parasitized (n = 83) ("# = 5.55, df = 1, P < 0.05). Parasitism based on distance to nearest neighbor is also observed (t = 2.261, P = 0.0266). To cope with parasitism and the loss of available pollen in the system, infested flowers shorten their male phase by approximately two days, from 4.2 ± 2.4 to 2.5 ± 2.1 days (t = 2.26, P < 0.21), while experiencing no significant difference in overall flower longevity (t = 0.55, P < 0.59). This results in an implied lengthening of the female phase in infected flowers, increasing the chances of pollination in the pollen-depleted system.

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  Attack pheromone response among colonies and castes in the leaf-cutting ant Atta cephalotes, June 2006

  Matthew Ward

  Attack pheromones in Atta cephalotes are important in coordinating defense responses to protect the colony. Little is known about the dynamics of A. cephalotes defenses and their underlying mechanisms (Whitehouse and Jaffe 1996). The objective of this study was to test for differences in response between four colonies and between the three classes of ant; minor, worker, and soldiers. Eight treatments were performed to carry out the two experiments. Toothpicks were coated with the attack pheromone from each of the four colonies and each of the three castes and one toothpick was tested without any pheromone as a control. Using a Kruskal- Wallis and Post- Hoc test, eight relationships were found to be significant. It was determined that the minor class is the primary attacking class for attack pheromones (Kruskal-Wallis p-value < .0001, df = 2). These data indicate that A. cephalotes follows the square law proposed by Franks and Partridge (1993). Initially, these minors responded more intensely to the pheromone of their own pheromones (Kruskal-Wallis p-value = .0036, df = 3). Over the full 20-minute duration of the trial they responded more greatly to the worker pheromone (Kruskal-Wallis p-value = 0.0042, df = 3). The response of the worker class during the trials was greater for the minor pheromone (Kruskal-Wallis p-value = 0.0099, df = 3). The overall response by A. Cephalotes was greater for the toothpicks with the attack pheromone than it was for the control (Kruskal-Wallis P-Value = .0260, df= 4). An interesting relationship was uncovered between two of the colonies studied. When the attack pheromone from colony C was placed in the trails of colony D, the response from the colony was not significantly different from that of the control for both the initial and total responses (respectively, Kruskal Wallis p- value = .0030, df = 4 and Kruskal Wallis p- value = .0269, df = 4). These data may have indicated that when colonies are close to one another, as colony C and colony D are, then interactions may cause the dynamic between them to change.

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  Call recognition in Brown jays (Cyanocorax morio), June 2006

  Lisa Michi

  Call recognition in birds is important so energy and time are not wasted. Many studies have used heterospecific calls that were evolutionarily distant from the species being tested to show that recognition was possible. This study looked at species recognition of both an evolutionary distant species (common potoo, Nyctibius griseus: Nyctibiidae) and of a species in the same family (magpie jay, Calocitta formosa: Corvidae) in brown jays (Cyanocorax morio: Corvidae). Three different calls (brown jay, magpie jay, and common potoo) were played in ten different territories of brown jays in the Monteverde area during the dry season. Results suggested that brown jays could distinguish their call from the other two species (p = 0.019). Brown jays also responded more strongly to the magpie jay call than to the common potoo call, suggesting that evolutionary similar species have similar structure to their calls as opposed to evolutionarily distant species.

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  Community composition of frugivorous butterflies in a Neotropical land Mosaic, June 2006

  Emily Heim

  It is important to consider land transformation and its effects on species abundance, richness, and diversity. Frugivorous Nymphalid butterflies, baited using fruit-traps, were used to assess trends in diversity for a mosaic of three habitat types (forest, edge, and pasture) in a premontane wet Costa Rican landscape. Results showed more species in the pasture habitat, but a higher richness, evenness, and diversity in the forest habitat. Integration of conservation areas in the expanding array of human-impacted landscapes is necessary to best maintain regional biodiversity in the long term.

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  Diapause aggregations in Stenotarsus sp. (Endomychidae), June 2006

  Alison Bernhardt

  Stenotarsus sp. (Endomychidae, Coleoptera) are handsome fungus beetles, which feed on fungus and rotten wood. The genus Stenotarsus is well known for its formation of large aggregations often composed of several layers, during diapause. Stenotarsus sp. has been shown to form these aggregations for mating purposes, predator avoidance and water conservation. Therefore, given these reasons for aggregating this study predicts that larger individuals will have an advantage at acquiring positions low in the stacks and towards the center where they are less likely to be picked off by predators and will have an advantage in conserving water. This study also predicts that males will be found in the upper layers or on top of the females in order to copulate. A sample of Stenotarsus sp. was collected from the diameter of an aggregation and analyzed to determine if there were any relationships between sex, size, stacking and distance from the center. A biased ratio of females was found which could suggest that many of the males had already dispersed. Males were found to be significantly larger than females for two different size measurements showing that the beetles are sexually dimorphic. The results did not support the predictions that larger individuals would be found in the best positions and that males would be found above females.

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  Different agricultural management practices concerning soil fertility: case studies of six rural Monteverde farms, June 2006

  Katie Stalland

  This paper reports on six case studies of small scale agricultural practices and soil fertility for six farms of Monteverde, Costa Rica. Data were collected through interviews with farmers regarding agricultural techniques and from soil. Samples from various areas of each farm were analyzed for nutrient contents (N, P, K, pH, and humus). The majority of farmers were found to be utilizing numerous techniques in order to increase soil fertility, though methods differ greatly between farms. Results indicate that organic fertilizers, compost, and manures were effective in increasing soil nutrient levels. Two foliar fertilizers were tested to assess nutrient degradation over time, and results showed an increase in nutrient concentration over time for one of these. Recommendations are made for local farmers to apply some form of compost, manure, or foliar fertilizer to increase nutrient content. Analysis of interviews which highlighted a large range in management practices leads me to recommend increased communication between farmers and citizens within the community, increased awareness of effective agricultural management techniques, and support increasing use of sustainable and organic methods of agriculture.

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  Dry season macrofungi of the Monteverde reserve, June 2006

  Sara Williams

  Fungi make up a great portion of the biodiversity of the planet, yet they remain poorly described and sorely understudied. Generally, fungi field guides are only available at the country level. A database for the macrofungi of the Monteverde Reserve was started in the fall of 2005, creating an identification guide at the local level. The aim of this study was to add samples to the database, expanding particularly to include fungi specimens of the dry season. The main goal of establishing a macrofungi database of the area is to induce and facilitate additional fungi research.

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  Edge effects on understory Rubiaceae communities in lower montane moist forest at Monteverde, Costa Rica, June 2006

  Jenna Halsey

  Understory plants are important to tropical forest structure as they support diverse communities of frugivorous birds, insects, and mammals. The biodiversity in understory communities is becoming increasingly altered as fragmentation of forests exposes more land to edge effects. Rubiaceae is a common understory fruiting plant family that can be found in forest fragments in tropical and subtropical regions. This study examined the effects of distance from a pasture edge on the abundance and species richness of Rubiaceae. I tested a total of ten transects that ran 68 m deep into the forest fragment. Each transect contained four 2x2 m2 plots, and each plot was placed 20 meters apart. I took a census of Rubiaceae species in each plot and calculated the abundance and species richness. I tested for a significant gradient of abundance and species diversity across all plots, per transect. I found a strongly consistent correlation between abundance and species diversity and thus concluded that distance from the edge had a profound effect on Rubiaceae. I also tested the effects that distance from the pasture edge had on the overall composition of Rubiaceae in the forest. I found that the composition of the plot nearest to the edge differed to a great extent from the farthest plot. Thus, edges also have a great effect on Rubiaceae composition. The effects of edges on crucial understory plants, such as Rubiaceae, are important to tropical and subtropical conservation and management.

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  Effects of weevil parasitismo n a Cecropia-Azteca mutualism, June 2006

  Scott J. Edmundson

  Mutualisms, beneficial interactions between organisms, are complex and often involve many species. Parasites on mutualisms disrupt the energy exchange and recycling between the mutually benefited species. This experiment explores the mutualism between Cecropia obtusifolia and Azteca xanthacroa and the effects of a parasitic disruption. Levels of fitness were estimated for sapling C. obtusifolia by measuring Müllerian body production and leaf herbivory. In addition, fitness levels of ants were ascertained by using the number of ants actively patrolling the top four nodes of the sapling as an estimation of the colony number. Results demonstrated that the Müllerian body production rate is significantly positively correlated with the number of ants actively patrolling (regression analysis, R2 = 0.530, p-value = 0.0003, n = 20). The number of ants did not significantly correspond with increased percent leaf herbivory, although a trend that an increase in ants conferred a decrease in herbivory was noticed (regression analysis, R2 = 0.093, p-value = 0.205, n = 20). The percent of trichilia infected by a petiole weevil (Curculionidae: Zygopinae), corresponded negatively with the rate of Müllerian body production (regression analysis, R2 = 0.492, pvalue = 0.0006, n = 20). Saplings that had any amount of infested trichilia had significantly less ants patrolling (Mann- Whitney U test: U = 13.5, p-value = 0.0055, n = 20). I also found the greater the degree of trichilia infestation, the higher the levels of herbivory (regression analysis, R2 = 0.286, p-value = 0.015, n = 20). These results suggest that this parasitic interference may reduce the fitness of one or both of the partners in the mutualism.

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  Epiphyll community diversity on Anthurium and Philodendron (Araceae), June 2006

  Ellen Frondorf

  Little is known about epiphyll community diversity. This study compared epiphyll diversity growing on leaves from Anthurium and Philodendron. I hypothesized that the effect of a collecting vein, present on Anthurium, but not on Philodendron, would affect microhabitats and epiphyll species diversity. I predicted lower epiphyll abundance on Anthurium than on Philodendron. Fifteen leaves were collected from each plant species. Morphological species of epiphylls were counted for total percent cover, as well as the total area of the leaves. The Shannon-Weiner Index was used, along with Margalof’s index of richness. Analysis was done at metacommunity (all the leaves of Anthurium and Philodendron) and the local community (individual leaves of Anthurium and Philodendron) levels. Species richness was significantly greater in both communities, as well as the number of epiphyll occupied boxes for Philodendron. Evenness was equal at the metacommunity level (EPhilodendron = 0.62, E Anthurium = 0.61), but at the local community level, Anthurium had higher evenness of epiphyll species (EPhilodendron = 0.56, EAnthurium = 0.67, Mann Whitney U' = 163, p = 0.04). I hypothesized that the underlying reason is that the collecting vein gives a path for water to leave the leaf, resulting in a drier and more homogenous habitat of the leaf surface. Therefore, no niche-specializing epiphylls can become too abundant. Further studies need to be conducted on collecting veins and homogeneity, coupled with the specialized niches of epiphylls.

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  Food choice in frugivorous bats, June 2006

  Lauren Riegler

  Frugivorous bats are important dispersers for many tropical plants and their conservation depends on furthering knowledge in their foraging behaviors and food preferences (Brosset et al. 1996). This study investigated a possible fruit preference of five frugivorous bat species (Carollia brevicauda, Artibeus lituratus, Artibeus jamaicensis, Artibeus toltecus and Platyrrhinus vittatus) found in Monteverde, Costa Rica among three wild fruit species (Solanum umbellatum, Solanum aphyodendron and Ficus pertusa) and two cultivated fruit species (Musa accuminata and Carica papaya). Fruits were presented to the bats in the Bat Jungle of Monteverde, where the foraging of bats can be closely observed. Artibeus toltecus showed a slight trend of preference for Solanum umbellatum over Solanum aphyodendron. However, due to small sample size and pseudoreplication there was no significant preference for any of the fruits by any of the bat species.

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  Foraging behavior and diet preference of Dasyprocta punctata, June 2006

  Lauren Eberhart

  This study analyzed the foraging behaviors and diet preference of the agouties (Dasyprocta punctata) in Monteverde, Costa Rica. The Optimal Foraging Theory explains animal behaviors in terms of maximum efficiency; animals forage in a manner that is optimal to their fitness (Alcock 2005). D. punctata was expected to choose the fruit over seed because fruits would provide more energy for the time spent foraging and, therefore, maximize foraging efficiency. Also, D. punctata have been found to eat fruit when the supply is abundant (Smythe 1978). Syzygium malaccense was used to test whether entire fruits were preferred over naked seeds. A total of 154 seeds and fruits were made available during the experiment; 124 were removed, 59 seeds and 65 fruits (Fig. 3). No significant differences were found between seed or fruit preference (Χ2 = 0.290, p = 3.84). Neither seeds nor fruits were eaten or cached at a significantly different rate (t = 0.14, p = 2.1). Differences found between the distances of the caches were not significant either (t = 0.0008, p = 0.678). No overall preference was found in the diet choice of D. punctata. Optimization may not be as straightforward as the amount of food consumed per unit time. D. punctata appeared to maximize their foraging efficiency by not being selective in food choice. Having an abundant food store provides year-round access to food, therefore alleviating environmental pressures.

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  Hummingbirds and pollen flow in a Neotropical agricultural mosaic, June 2006

  Amy Strieter

  Land transformation in the Tropics leads to greater landscape and forest fragmentation, creating land use mosaics. Some species adjust to new habitats while others go extinct. Adaptability is more complicated, however, when a species is involved in a mutualistic relationship. If host plants are spatially isolated, their pollinators may or may not be able to continue linking that subpopulation to the metapopulation; the pollinator population in turn may suffer due to decreased food supply, habitat, etc. This study examines hummingbird responses to a tropical agricultural/forest mosaic and tracks artificial pollen flow between feeders in different habitats. Hummingbird presence was monitored at feeders in forest, pasture, coffee, and banana crops, and four intermediate edges. Most hummingbird species were not found exclusively at their predicted habitats, and total species richness for each habitat type were not statistically significantly different (Chi-square = 5.762, df = 3, p = 0.12). Habitat edges did not appear preferred or avoided by hummingbirds, and diversity was essentially even across the land use mosaic. Additionally, hummingbird feeders were set with fluorescent dye powder as a “pollen” donor and adhesive tape as a collector. Pollen incidence and ranked pollen counts suggest that pollen from every habitat is moving to every habitat, with the exception of pasture pollen. Results indicate that having agricultural edges, crop variety, and crops in proximity to one another is more useful to several hummingbird species than homogeneous crop areas.