Monteverde Institute: Tropical Ecology and Conservation

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  Preferential oviposition by Heliconiinae (Nymphalidae) butterflies on Passiflora biflora (Passifloraceae) leaves with higher cyanide concentrations, May 2008

  Phillip Burkholder

  Passiflora spp. produces cyanogenic glycosides to prevent herbivory. The butterfly subfamily Heliconiinae (Nymphalidae) has broken through this defense with the ability to ingest the cyanogenic compounds. A coevolutionary arms race of adaptations and counter-adaptations followed, in which it is believed that Passiflora spp. evolved a series of counter-adaptive defenses, like egg-mimics, leaf shape, and extrafloral nectarines, to specifically combat heliconiines. While sometimes overcoming these adaptations, heliconiines still consider them for oviposition. Additionally, the role of cyanide may also have an effect on oviposition. It has been suggested that while detrimental to larvae, cyanide provides protection that promotes oviposition. There are also numerous studies suggesting defensive and nutritional benefits of CN when Heliconiinae is able to sequester cyanogenic compounds. Many times there are trade-offs in the defenses of young leaves, which might suggest that cyanide indicates fewer defenses. This study examines the role of cyanide (CN) concentrations in Passiflora biflora on ovipostion by Heliconiinae. Two studies were performed on cyanide preference. First, an analysis of cyanide concentration in similar leaves with and without eggs was conducted. Second, leaves had their cyanide concentrations artificially increased with CN/methanol extract and were then monitored for oviposition. When analyzing the cyanide concentrations of similar leaves with and without eggs, a trend of preferential oviposition on leaves of higher cyanide concentration was observed. There also seemed to be a two-fold difference, on average, between leaves with and without eggs, 0.50µg and 0.25µg CN respectively. The second study showed a preference for leaves with CN/methanol extract to leaves with extract alone and leaves with no alteration with eggs totaling nine, one, and one, respectively. This study suggests the importance of cyanide concentration for oviposition by heliconiines. This behavior might be explained by the protection provided from non-heliconiine herbivores or by possible nutritional and chemical benefits associated with the sequestration of CN. Additionally, if trade-offs are present, cyanide might indicate fewer non-cyanide defenses.

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  Range change in Cecropia and Azteca: the effects of climate change on mutualistic partners in Monteverde, Costa Rica, May 2008

  Garrison Loope

  The effects of climate change on the fauna of the Monteverde area has been well documented for vertebrate taxa such as birds, anurans, Norops spp, (Pounds 1999) and bats (LaVal 2004), but like the rest of the world little work has been done on the effects of climate change on invertebrates. This study examines the altitudinal ranges of the four species of Azteca and the three species of Cecropia living between 1500 and 700m in an area from Monteverde-Cerro Plano to San Luis. The current ranges of species are compared to elevations from a 1985 survey by John Longino (Longino 1989) and a 2003 survey by Mazzei (2003). In the last 23 years two species, A. xanthochroa, and A. alfari, are shown to have moved significantly up slope with a change in mean elevation of 103m, and 100m (P= .0018, and .0348). A. constructor shows no evidence for upslope movement but it increased its relative population size threefold over that reported by Longino (1989). The lowermost Azteca, A. coeruleipennis, has not shifted with climate change but its distribution may be restricted by the range of C. peltata. The two ant-housing Cecropia species did not have significant changes in means, but the upper of the two, C.obtusifolia, did show an extension of its range upslope as well as an increase in hybrids between it and the uppermost non-ant-housing species C. angustifolia. These data are unique in showing the effect of climate change on invertebrate populations. Although the impact of climate change on invertebrates throughout the world has been poorly studied, this study suggests that they can be heavily impacted by climate change.

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  Small mammal diversity and population densities in Monteverde, Costa Rica: A follow- up study of Rothman (1999), May 2008

  Caroline C. Burdick

  Widespread deforestation and El Niño events may have an effect on Costa Rican’s climate, and overall, Monteverde’s climate is becoming drier and less predictable due to short-term global warming impacts. Due to widespread habitat fragmentation and hunting, the population of small and medium-sized mammals has decreased dramatically. This study investigates rodent species richness, abundance, and diversity in three life zones in Monteverde, Costa Rica, to determine whether they have changed since a similar study conducted in 1999. Small mammals were sampled in Tropical Lower Montane Wet Forest, Tropical Premontane Moist Forest, and Tropical Lower Montane Rain Forest in the Monteverde region, Costa Rica, during the end of the dry season in mid-April, early-May. Data were collected using thirty 26 x 10 x 12 cm Sherman Live Traps. In 15 nights of trapping (450 total traps), 47 individuals were captured (with a few recaptures). Overall, six species and two orders were represented: Murid and Heteromyid rodents included 33 P. nudipes, six S. teguina, four H. desmarestianas, one O. albigularis, and one R. rattus. Order Insectivora was represented by two soricid shrews, C. gracilis. The mid-elevation site (see comments about “mid-elevation below) had the lowest rodent abundance, and thus differing greatly from the results of Rothman’s study. Furthermore, P. nudipes was absent from this site. Changing climate conditions could be partially responsible for the missing P. nudipes and relatively low abundance in the Tropical Lower Montane Wet Forest life zone, but also chance could play a strong role, as could sampling methods.

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  Sugar preference across butterfly families, May 2008

  Juliana Olsson

  Adult butterflies have a carbohydrate-based diet, acquiring their sugars mostly from nectar or from rotting fruits. Fruit-eating butterflies most often encounter fructose and glucose (Omura and Honda, 2003), while nectarivorous butterflies may encounter hexose-rich nectars in short-corolla flowers or sucrose-rich nectars in long-corolla flowers (Baker and Baker, 1983). This study explores the possibility that butterfly species exhibit certain sugar preferences that reflect not only their diet but their phylogeny as well, since feeding habits are often the result of co-evolution with pollination syndromes in the case of nectar-feeding butterflies. Butterflies from as many species as possible were given a solution of either 20% sucrose by weight or a 20% solution of combined glucose and fructose. The amount imbibed was recorded for the 26 species caught. No obvious preference for either sucrose or hexose nectars were uncovered. Butterflies would drink from either solution, indicating that fruits and flowers offering either sugar would be acceptable to most butterflies and that sugar preference is not as rigidly an evolved trait as was thought. However, minor trends towards sucrose preference are compelling grounds for further study.

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  The effect of flower angle on bat pollination of Mucuna urens (F. Papilionaceae), May 2008

  Laura Grieneisen

  The purpose of this study is to examine the relationship between bat pollination and flower angle in Mucuna urens (F. Papilionaceae). To determine the natural variation among M. urens, the angles of 100 M. urens flowers were measured with a protractor to the nearest 5o. The mean angle was -82.45o from the horizon, the mode was -90o, and the range was from -45o to -105o. Approximately one-third of the flowers were tied so that they opened at 90o greater than the natural angle, one-third were tied to open at 90o less than the natural angle, and one-third were left at the natural angle. Over several nights, the pollination status of 383 mature M. urens flowers was observed. More flowers than expected were pollinated at the natural angle and fewer flowers than expected were pollinated at the positive and negative angles. (X2 = 63.96, p<0.001, df = 2). This suggests that natural M. urens flower angles are more accessible to bats than other angles.

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  Use of shade trees to reduce leaf herbivory of Coffea arabica by Atta cephalotes (Formicidae) on farms in Cañitas, Puntarenas, Costa Rica, May 2008

  Tyler H. Stuart

  The addition of a specific group of rapid-growth shade tree species to coffee in monoculture, or the inclusion of these species in shade-grown coffee, may reduce leaf herbivory by Atta cephalotes. This study was conducted in Cañitas, Costa Rica on three plots—shade-grown, monoculture, and no coffee—within coffee plantations, each of which had a separate A. cephalotes colony. After observing the selection process of the leaf-cutter ants among four non-coffee, shade tree species and two varieties of coffee, Caturra and Katway, results indicated that the ants had no preference(s) of the tested species within any of the tested plots (Shade: K-W = 0.976, p = 0.98; Monoculture: K-W = 1.319, p = 0.971; No Coffee: K-W = 0.803, p = 0.992; All plots: df = 6, n = 35). The ants more frequently selected Erythrina lanceolata at the Shade-Grown Plot than the other two plots (K-W = 7.22, n = 15, df = 2, p = 0.027). These findings may have important implications for both coffee farming and the restoration of biodiversity in monoculture crops.

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  UV-blocking chemicals in forest canopy and understory lichens, May 2008

  Katherine Rose Heal

  Lichens produce over eight hundred secondary metabolites, many of which are found nowhere else in nature. Many of these chemicals have UV-blocking properties, including usnic acid and many depsides. These chemicals could affect colonization success between understory and canopy lichens. In Monteverde, Costa Rica, a total of 244 lichens were extracted from six trees, half from canopy branch tips and half from the trunk in the understory. Canopy coverage was significantly higher in the understory (t-test, F = 88.78, p < 0.05). In the pooled population, usnic acid was present in the branch tips more often than on the trunks (after Yates correction factor X2 c = 26.23, df = 1, p = 3.03E-07). Conversely, depsides were present more often on the trunks (after Yates correction factor X2 c = 26.23, df = 1, p = 3.02E-07). The differences in the chemical constituents, which are associated with differences in lichen community composition, may reflect adaptations that allow niche partitioning along light gradients.

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  Atta cephalotes (Formicidae) as a reliable bioassay for anti-fungal compounds in plants of Monteverde, Costa Rica, December 2007

  Annie Chisholm

  Studies have shown Atta cephalotes (Formicidae) to be selective in choosing host plants, avoiding those that contain nonpolar secondary compounds harmful to their mutualistic fungus (Howard 1988). Due to this selectivity, several studies have found A. cephalotes to be a reliable bioassay tool for detecting antifungal properties of plants (Ozaki 1993; Taylor 1995). This experiment tests the acceptability of A. cephalotes towards six Costa Rican plants with known anti-fungal compounds. It was hypothesized that A. cephalotes would selectively avoid extracts of these plants. The frequency of removal of oat flakes dipped in the anti-fungal and control treatments was measured. A. cephalotes preferred the control to the anti-fungal extracts for six of the seven treatments: Allium satium, Oreopanax sp., Phytolacca rivinoides, Nectandra membranacea, Bocconia frutescens, and the commercial fungicide (10% propanodiol). However, there was no difference in preference between Heliconia sp. and control treatments. These results suggest that this species is a reliable bioassay tool for detecting anti-fungal compounds in medicinal plants.

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  Behavioral response of wrens (Troglodytidae) to familiar and unfamiliar predator playbacks, December 2007

  Carl D. Johnson

  Predator-prey interactions are important for determining fitness, especially including a prey species’ ability to distinguish a predator from a non-predator. In this study, I investigated how three wren species: the Plain Wren (Thryothorus modestus), the House Wren (Troglodytes musculus) and the Rufus-and-white Wren (Thryothorus rutilus) respond to familiar and unfamiliar predatory calls. The test subjects responded with higher warning call frequency to the predatory calls than the control (p<0.05). Wrens responded to the two predatory birds with similar call frequency, though there were varied responses in approach behavior. The fact that wrens respond to unknown predators similarly to known predators implies that a combination of both genetic inheritance and learning affects predatory birdcall recognition in wrens.

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  Differences in bark beetle (Coleoptera: Curculionidae) community composition within Cecropia obtusifolia (Cecropiaceae) petioles in two habitats in Monteverde, Costa Rica, December 2007

  Amy Strauss

  Cecropia obtusifolia trees shed leaves daily throughout the year, regularly dropping large, woody leaf petioles. These petioles serve as the perfect habitat for Scolytine bark beetles, which burrow in, lay their eggs, and feed on the moist, fibrous pith of the petiole (Wood 1983). Cecropia spp. are known to thrive in fragmented, edge habitats altered by human land use transformation (Bello et al 1996) but success rates of associated fauna, including Azteca spp. ants, scale insects and Scolytine beetles, are less understood. This study examined the bark beetle community composition, morphospecies richness, and abundance inside C. obtusifolia petioles. It also investigated the rate of petiole colonization by Scolytine beetles, comparing two habitats: a C. obtusifolia population occurring in a forest tree fall light gap, and a population occurring along a neighborhood road. Both populations were located in Monteverde, Costa Rica. Fallen, dead petioles were collected and dissected from each habitat type, and all fauna found inside the woody petioles were removed, identified, and recorded. They were identified as either a Scolytine larva, one of five observed Scolytinae morphospecies, or a non-Scolytine organism. Differences between observed beetle communities in the two studied habitats were then compared. This revealed equal species richness and equal rates of petiole colonization for beetle communities at each site. The human disturbed habitat had greater Scolytinae abundance, while the forest light gap habitat had greater diversity due to higher evenness of morphospecies abundances. This is explained by the particularly high abundance of one morphospecies in disturbed habitat beetle communities. Overall, there were few evident differences between Scolytinae communities in the two examined habitats, indicating that observed Scolytinae populations are adaptable to human-caused habitat alterations and can disperse to fragmented C. obtusifolia trees. Their maintained survival and reproduction rates indicate that C. obtusifolia associated Scolytinae beetles are poor indicators for biodiversity loss and impacts on species relationships that result from continued global deforestation and habitat degradation.

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  Differential aboveground adventitious root production by Senecio cooperi (Asteraceae), December 2007

  Nathan J. Ebnet

  Previous studies have suggested that aboveground adventitious roots (AARs) are produced by plants in order to extract nutrients from the epiphytes they support (Nadkarni 1981 & 1984). I asked whether Senecio cooperi, a neotropical plant which produces AARs, generates these roots for nutrient absorption, fragmentation establishment, or structural support. I conducted a survey in which I measured multiple characteristics of S. cooperi and their AARs in Monteverde, Costa Rica. Naturally fragmented stems produced more AARs than expected by chance (x2 = 12.80, df = 1, p < 0.05). No purely vertical stems contained AARs associated with the moss mats growing on them. However, vertical stems displayed basal AARs which increased in diameter as both plant height and DBH increased (R2 = 0.330, P < 0.001, N = 50, R2 = 0.402, P < 0.0001, N = 50 respectively). These findings suggest that the naturally occurring role of AARs of S. cooperi are not for nutrient absorption, but rather for structural support and fragmentation regeneration. These functions of AARs allow S. cooperi to be more successful as a pioneer species in disturbed habitats, and highlight the need to reevaluate the functionality of AARs among other plants.

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  Ecotourism as a driver of forest conservation on small farms in Costa Rica, December 2007

  Sarah Owens

  Conservation of fragmented forest on private land is instrumental to long-term protection of tropical biodiversity. However, few incentives exist for small landowners to conserve. This study addresses ecotourism as an incentive for forest fragment conservation. Small farmers were interviewed to determine the extent of land in regeneration or protection and the ecotouristic activities on each property. The data suggest that a greater percentage of land is in regeneration on farms with small-scale tourism (20% + 10.1) than on farms with large-scale tourism (12% + 6.0) and no tourism (5% + 2.1; Kruskal-Wallis Test, H = 6.0673, p = 0.0481, N = 19). I conclude that of the farms employing tourism, three types of private property classifications exist: 1) land that would be conserved with or without tourism, 2) land whose maintenance benefits from ecotourism directly, and 3) land with tourism that is not ecological, but could still contribute to conservation. Each property type is addressed with a specific conservation strategy that could enhance long-term biodiversity protection in the Monteverde area.

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  Evidence of subsocial behavior through analysis of prey capture and feeding in a new species of Anelosimus (Araneae: Theridiidae), December 2007

  Aaron Mitchell-Dick

  Sociality is a little studied, little occurring, and unique trait in spider biology. Recently, in the genus Anelosimus, where sociality has originated eight or nine times, research has shown that more quasisocial species exist at low elevations and almost all subsocial species at higher elevations. The purpose of this study was to determine the sociality of a new species of Anelosimus, and add to the knowledge base of social Anelosimus spiders. Analysis of prey capture and feeding has provided evidence for a subsocial classification. In 12 webs of a female and her offspring, juveniles coordinated efforts to capture prey. Almost all of the spiders in the web fed communally (R=0.97; p=.0001). Juveniles more adeptly captured prey smaller than their body size prey, and spent longer capturing prey larger than their body. Other natural history aspects of these spiders were described, including guarding of egg sacks, web heights of 0.2m-2.3m, and tendency of webs to be found on tips of branches. With as much knowledge as to the extent of sociality in Anelosimus, we may be able to accurately analyze trends, and provide insight into the mechanisms of evolution and their origins.

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  Influence of resource availability on the foraging behavior of traplining hummingbirds in Monteverde, Costa Rica, December 2007

  Michelle Levesque

  Traplining hummingbirds have been observed to change their foraging behavior in response to a change in resource availability. Generally, trapliners change to territorial behavior when presented with an economically defendable resource. I investigated the degree to which aggressive behavior increases by observing changes in behavior frequency in response to increased resources. I observed that trapliner species showed an increase in aggressive behavior and a decrease in the total frequency of traplining behavior following the introduction of increased resources. My study also supports that traplining hummingbirds could switch their foraging behavior to territoriality when resources become economically defendable.

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  Mycorrhizal fungi in epiphytic and terrestrial Oerstedella exasperata (Orchidaceae), December 2007

  Nicole M. Williams

  All orchids have a relationship with mycorrhizae during germination. Nutrient availability in soils often determines whether these relationships are maintained into adulthood. The aim of this study was to investigate the frequency of mycorrhizae infection in epiphytic and terrestrial Oerstedella exasperata. Since orchids that are rooted in the ground may have greater access to, or more consistent supplies of, nutrients I predicted that mycorrhizae would be found less often in terrestrial individuals. Furthermore, since plant fitness may be affected by the presence or absence of mycorrhizae or the availability of nutrients, fitness of epiphytic and terrestrial plants, with and without mycorrhizae were compared. I found a difference in the frequency of infection between the two substrate types with terrestrial individuals showing a higher frequency than expected by chance and in frequencies that exceeded those for the epiphytic individuals. Significant differences were not found in fitness parameters for orchids between the two substrates but trends were found that showed individuals occurring on both substrate types did better with the presence of mycorrhizae.

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  Niche partitioning between Eisenia foetida (Lumbricidae) and native earthworms in Monteverde, Costa Rica, December 2007

  Christine Askham

  With an increased susceptibility to invasive species due to deforestation, exotic species in tropical rainforests are quickly gaining potential to alter these already disappearing ecosystems. This study examined whether the exotic earthworm Eisenia foetida (Lumbricidae) has the potential to become an invasive species. Niche preference for level of organic soil content, level of soil texture, and humidity level was tested between native and exotic species in Monteverde, Puntarenas, Costa Rica. There was a significant difference for organic soil content level between native earthworms and E. foetida. This significant difference was present both when the exotics and natives were tested alone and in each other’s presence. Native earthworms avoided high organic content while the exotic earthworms preferred it. No significant difference between preferences of native and exotic worms was found for varying levels of soil texture. Both native and exotic earthworms were most abundant in the low soil texture level when tested alone. Native worms resided an average distance farther from the water source than exotic worms.

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  Pollen diversity on male Hylonycteris underwoodi (Glossophaginae), December 2007

  Julia Hoeh

  Nectivorous bats play important roles in pollination systems in the tropics, by transferring pollen carried on their bodies between the plants that they visit for nectar. The purpose of this study was to evaluate diversity indices of pollen loads found on individuals of Hylonycteris underwoodi (Glossophaginae). It was conducted in the Selvatura Adventure Park in Monteverde, Costa Rica during the rainy season, and related pollen load diversity to aspect ratio, wing tip index, and mass of individuals (N = 30 males). The pollen load on individuals had low richness (2.20 ± 0.81), diversity (0.09 ± 0.16), and evenness (0.09 ± 0.15) due to the large abundance of Markea sp. pollen grains. Markea sp. was present on every individual, suggesting a specialization by H. underwoodi. Neither the variation of the overall pollen load nor the variation in the abundance of Markea sp. pollen grains could be explained by aspect ratio, wing tip index, or mass of the individuals.

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  Relationship between floral advertisement and pollinia removal in Oerstedella exasperata (Orchidaceae), December 2007

  Mary Snayd

  The purpose of this study was to examine how the floral displays and morphology of Oerstedella exasperata affect reproductive success. This species of orchid is typified by extreme variability in both inflorescence and floral characteristics. In particular there is a wide distribution regarding the degree of symmetry observed in the labellum. The degrees of symmetry are characterized by variations within the fringe symmetry and bilateral symmetry. Furthermore, the surface area of the labellum varies greatly within a population. These remarkably diverse phenotypic morphologies and the summation of the floral traits can enhance or reduce the reproductive success of particular species. To test the relationship between floral advertisement and reproductive success, each flower was examined and grouped according to pollinia presence or removal. Results indicated that pollinia removal was not affected by the degree of bilateral or fringe symmetry or by the size of the labellum. Furthermore, within the 100 individuals examined, the asymmetrical trends were considered directional for bilateral symmetry but nondirectional for fringe symmetry.

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  Selection for survival: soil grain size preference and body size in wormlion (Vermilio sp.) larvae affect pit trap construction, December 2007

  Alice McCarthy

  Sessile predatory larvae rely on their habitats to provide biotic and abiotic factors needed for sufficient prey capture. I examined the hypothesis that for Vermilio sp. (wormlion) larvae, body size and soil grain size affect pit trap size and prey capture efficiency. At the Estación Biológica de Monteverde in Costa Rica. I measured and compared larva size versus pit trap size, put larvae in containers with half fine grain soil (< 2 mm) and half coarse grain soil (2mm to 6mm), tested for preference, and compared size of pit traps constructed in the two soil types. I also dropped ants into pits and measured time to escape and frequency of capture by the larvae. Pit trap size was positively correlated with larva size. Larvae preferred fine grain soil over coarse grain soil ( χ2 = 45.08, df = 1, P < 0.01) and constructed traps less often in coarse grain soil. I found no difference between pit trap sizes in fine and coarse grain soil, yet sample size was small and I noted the trend that ants remained trapped in fine grain soil longer than in coarse grain soil. Preference for fine grain soil indicates habitat selection of larval Vermilio sp. for areas that increase prey capture, therefore promoting the survival of the species.

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  The role of cyanide in oviposition by Heliconius (Nymphalidae: Heliconiinae) on Passiflora (Passifloraceae), December 2007

  Zach Sheff

  Vines of the Passifloraceae contain cyanide that deters most potential herbivores but not Heliconius spp. (Nymphalidae: Heliconiinae). Despite their ability to cope with cyanide in Passifloraceae, Heliconius spp may preferentially oviposit on leaves with lower cyanide concentrations, as young larval stages may still be subject to toxicity. Leaf samples both with and without eggs were collected from Passiflora spp. from the Monteverde Butterfly Garden and were assayed for cyanide concentration. There was no significant relationship between cyanide concentration and oviposition (mean concentration with eggs = 6.04 + 9.41 (μg/mg), mean concentration = 11.13 + 18.84 (μg/mg); t = 1.15, p = 0.26, df = 42). Thus, ovipositing Heliconius are either indiscriminate in their choice of leaves or are selecting leaves based upon other traits that are more important to determining egg survivorship or early larval development.

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  Effect of minima on the velocity of the workers in Atta cephalotes, August 2007

  Nicholas J. Fabeck

  The leaf-cutting ant, Atta cephalotes, creates trails of foragers which carry leaf fragments to the nest. A division of labor is created based on ant body size (Stevens 1983). The smallest members of the caste system, the minima, “hitchhike” on the leaves of workers returning to the nest. My study was performed on a large colony in Monteverde, Costa Rica to research the cost of efficiency to the colony in relation to velocity with minima travelers. I hypothesized that load size affects velocity of the worker and predicted that an increased load size will negatively influence velocity. I collected Atta workers (n = 240) with leaf fragments and their minima and measured their velocity and ant, minima, and fragment mass. Though it was discovered that more minima travel on smaller leaves (2 = 1990.13 p = < 0.001, df = 2), there was no significant relationship between increased load mass and velocity. The heavier load by the minima may be a trade off by foragers for the protection from parasitic flies that prey on workers.

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  Feeding preferences of captive Morpho peleides at the Monteverde Butterfly Garden, August 2007

  Beth Wright

  Morpho peleides is one of many tropical butterfly species that are fruit-feeding butterflies. In this paper, I will (1) explain the importance of biochemical components in banana pulp including amino acids, sugar, and alcohol in the diet of M. peleides and how it affects the butterflies’ food choices, and (2) suggest how fermentation might encourage or discourage food preferences banana pulp with high or low concentrations of alcohol. Six combinations were tested in this study: mature pulp with amino acids, mature pulp with water, mature pulp with rum, overripe pulp with water, overripe pulp with amino acids, and overripe pulp with rum. There was no significant difference among average feeding durations (ANOVA: F ratio = 1.60; p value = 0.16; df = 5) or among frequencies of visits between each food type (Chi-square Goodness of Fit: 2 = 8.77, p > 0.05). The similarity between visit times and frequencies for banana pulp samples with higher concentrations of amino acids and rum can be explained by (1) previous research suggesting that it is more common for nectar-feeding butterflies to have preferences for amino acids than it is for fruit-feeding butterflies like M. peleides, and (2) nutritional compensation of overripe bananas via (a) more amino acids released from the peel into the pulp or (b) higher sugar concentration peaks later on in the maturation process combined with stronger odor cues that attract the butterflies.

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  Going batty: response of foraging glossophagine bats to auditorily perceived predator presence, August 2007

  Hannah Kim Frank

  Predator presence is known to alter the foraging behavior of many species leading to decreased resource acquisition and lowered reproductive rate (Werner 1994). Previous studies have examined the effect of predator presence on the emergence of roosting bats and the effect of predator models on foraging bats (Baxter et al. 2006). Only one study, however, has examined the importance of auditory cues in alerting foraging bats to the presence of predators (in this case, owls; Baxter et al. 2006). The study concluded that bats not only avoid perceived owls but also the call of a diurnal woodpecker, leading the authors to question whether the latter finding was the result of novel sound avoidance or acoustic interference. This study, conducted in Monteverde, Costa Rica, investigated whether the findings of the earlier study were due to the effects of a novel sound or acoustic interference. Predator avoidance was quantified by counting number of visits to a hummingbird feeder after playing an owl call, a frog call or no call (a silent control). Significantly fewer visits were detected after the owl call than either the frog call or silence (ANOVA, F = 11.0203, p = 0.0001, df = 2) indicating the results of the previous study were due to novel sound avoidance. This study also reaffirmed the importance of auditory cues as a technique for predator detection in foraging bats, demonstrating a globally significant trait of bats.

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  Herpetofauna distribution and species richness along an elevational gradient, August 2007

  Beth Schlimm

  Monteverde, Costa Rica has experienced a significant increase in temperature and reduction in mist frequency in the last 20 years. These changes in abiotic conditions have been linked to the extinction 40 percent of local amphibian populations and several reptile species. The purpose of this study was to determine if the herpetofaunal community composition of Monteverde is still transitioning in response to continued changes in abiotic conditions. Reptiles and amphibians were censused along a 191 m elevational gradient to observe zonal distributions, and species richness and abundance. Species distributions were observed for shifts from their expected ranges. Visual and audio data were collected in the study. Visual data include collection of herpetofauna from trail transect day and night hikes and tree buttress plots while audio data consist of nighttime amphibian call documentation. Upslope shifts in distribution were found for three frog species. Species richness and abundance were not significantly correlated with elevation. Distributional shifts to higher elevations as demonstrated by the herpetofauna in this study seem to follow the trend of upslope shifts in cloud and mist distribution of tropical cloud forests. Changes in abiotic conditions including temperature, cloudiness and mist frequency may be exerting increasing pressure on herpetofauna that is resulting in distributional shifts and changing species richness trends in Monteverde.