Monteverde Institute: Tropical Ecology and Conservation

Follow

• 

  Arbuscular mycorrhizal fungi vesicles in Coffea arabica (Rubiaceae): Agroforestry and conventional coffee farms, May 2010

  Jason C. Kopp

  Due to their nutrient-poor soils, a pressing issue in tropical countries is the conservation of land through more sustainable agricultural practices in order to continue to feed their booming populations. Agroforestry is a possible sustainable solution, which reduces negative impacts on the environment, including impacts on mycorrhizal fungi. Mycorrhizal fungal associations within plants are important designators of a healthy crop and a more sustainable management system. This study investigates differences in arbuscular mycorrhizal fungi (AMF) vesicle abundance between the center and edge of an agroforestry coffee farm and the center of a conventional coffee farm. Eight different root samples were stained from each of the three locations using Trypan Blue (24 total root samples). The number of vesicles were then counted in three root segments from each of the 24 samples, and averaged for each location. Results showed a marginally statistically significant difference between all three locations (ANOVA, F=3.31, p=0.05, df=23). In addition, the center coffee plants in agroforestry had more AMF vesicles per root segment (28.04 ± 9.38 std) than roots at the center of conventional coffee (12.96 ± 11.23 std) and were statistically different; but neither were statistically different from coffee at agroforestry edge (21.17 ± 14.08 std; Tukey's Multiple Comparison, q=2.52, p<0.05). Although there was little difference in AMF vesicle abundance on a micro-scale within the agroforestry farm, there were more vesicles than in conventional coffee production. This could be attributed to the use of biological fungicide, greater moisture retention, or younger trees in the agroforestry farm.

• 

  Childhood outdoor experiences and current behavior: Attitude towards the environment and conservation, May 2010

  Katherine A. Wilson

  Pro-environmental attitudes are an important component of the base of conservation organizations. In order for conservation organizations to successfully protect and preserve natural habitats it is important to understand the origin of symbolic attitudes to the environment. The purpose of this study was to show how childhood experiences influence how an individual feels about the environment in adulthood. Ninety people in the Monteverde Region of Costa Rica answered questions pertaining to childhood experiences and current attitudes involving the environment. The study showed that childhood activities, such as playing outside, have a positive correlation with pro environmental attitudes and environmentally benefiting behaviors as an adult. I conclude that the people of Monteverde have a higher appreciation and concern for nature because being outside as a child caused them to build a positive relationship with nature. Conservation organizations should apply these results when recruiting new support methods.

• 

  Community composition and chlorophyll levels in lichens as indicators of atmospheric pollution in Monteverde, Costa Rica, May 2010

  Kathryn A. Graziano

  Lichens and their photosynthetic pigments are commonly used as bioindicators of atmospheric pollutants. This study compared lichen community structure and chlorophyll levels between two sites in the Monteverde region, Costa Rica, to determine the effect of local pollution. The first site, Santa Elena, is rapidly becoming more populated as a result of an increase in ecotourism, leading to heavy vehicle traffic. The other site, Bajo del Tigre, is secondary forest surrounded by a sparsely populated area far removed from automobile exhaust. Lichen samples were collected from each site. Chlorophyll was extracted with 90 percent acetone and degradation was measured as a ratio of absorbance between 435 and 415 nm, in which a lower ratio implied higher chlorophyll degradation and more pollution. No significant difference was found in chlorophyll between the two sites, and chlorophyll was degraded in all samples. Species diversity and evenness were higher in Santa Elena, while abundance was higher in Bajo del Tigre, resulting in no significant diffeence in species richness as measured by the Shannon Weiner Index. Factors affecting community composition may be too complex in the Tropics to use lichen species or diversity as bioindicators of pollution. Low chlorophyll levels may indicate that pollution has permeated the entire area as acid rain.

• 

  Crop size, ripening, and fruit removal in Solanum umbellatum (Solanaceae) by Phyllostomid bats, May 2010

  Eleanor Caves

  Effective seed dispersal is of primary importance to most plants. Maximum dispersal should result from a larger fruit crop, since large fruit crops are more obvious to frugivores; however, producing too many fruits can be detrimental to dispersal as it satiates the frugivore. Thus, plants must strike the proper balance to maximize dispersal. I examine the effects of ripe fruit density, ripe fruit number, and fruit crop size within infructescences on fruit removal probabilities (FRPs) of wild Solanum umbellatum in Monteverde, Costa Rica. Further, I examine preferences of frugivorous Phyllostomid bats for various proportions of ripe fruits. Each day, the ripeness status of 1537 S. umbellatum fruits was recorded. Simultaneously, flight-cage experiments were performed with five species of frugivorous Phyllostomid bat, in which the bats were offered arrays of three different proportions of ripe of S. umbellatum fruits. Results showed that FRP was independent of proportion of ripe fruits per infructescence on wild S. umbellatum, but was negatively correlated with total and ripe fruit crop size. In captivity, bats exhibited a significant preference toward fruit arrays with higher proportions of ripe fruit; however, over time the bats learned to eat from all arrays equally. These results suggest that, because frugivorous bats in nature are not naïve to S. umbellatum fruits (as they were in captivity), they can learn locations of fruiting plants; thus, S. umbellatum does not need to produce a certain proportion of ripe fruits to attract dispersers. Rather, frugivore selection may be driven by some unobservable factor, such as fruit nutritional quality.

• 

  Diversity of macroinvertebrate feeding guilds along a stream order continuum in San Luis Valley, Costa Rica, May 2010

  Tim Schrautemeier

  Under the surface of streams, there is dominance and compositional variance among biological communities, which normally goes unobserved. The River Continuum Concept (RCC) describes shifts in biological communities caused by shifts in abiotic factors along a longitudinal gradient of a river system. Macroinvertebrates, which are influenced by the RCC, were collected and identified from 18 sites along 3.6 km of the Rio San Luis. The Morisita Index of Similarity and cluster analysis showed a difference in upper and lower reaches of the river. Canopy cover and feeding guild composition were strongly correlated. Different families showed higher dominance with and without the presence of canopy. The RCC was supported by the stream tests, however, changes in biodiversity, composition, and abundance occurred in a much shorter distance than predicted.

• 

  Effect of ground temperature and nest differences on productivity and worker size in Atta cephalotes (Hymenoptera Formicidae), May 2010

  Hannah Fried-Petersen

  Atta cephalotes is one of the few species that does better in grassy pastures and secondary growth and their abundance, persistent foraging, and that they collect from a lot of different tree species has earned them the reputation of huge agricultural pests. A. cephalotes are poikilotherms meaning their internal body temperature fluctuates greatly with temperature. For this reason, it has been purported that these leaf-cutter ants will only collect leaf fragments at certain temperatures and that different sized workers have different temperature tolerances. The objective of this study was to look for relationships between temperature, productivity, and worker size in nests in Monteverde, Costa Rica. It was found that some nests’ productivity was more responsive to changes in temperature and that nest and temperature interact to predict worker size during foraging. Because of A. cephalotes’ large impact on the ecosystem in Monteverde (whether viewed as good or bad), it is important and interesting to know more about what regulates the speed of their foraging.

• 

  Effects of resource partitioning on the behavior and foraging activity of the Coppery headed emerald and the purple throated mountain gem hummingbirds (Trochilidae), May 2010

  Nicholas J. Buffin

  Organisms specialize in order to decrease the energy required to do certain activities, such as forage and feed. This study was done to see whether altering the flower size affected the specialization of species in terms of abundance and aggression. The abundance increased for the Coppery Headed Emerald (CHE)(from 91-118) individuals as it became more specialized, and decreased for all other species being studied. The Purple Throated Mountain Gem (PTMG) (255-196) was also looked at, as it was present in the greatest abundance both before and after the straws were added. The manipulation also altered the hummingbird’s aggressive behavior. The CHE became less aggressive interspecifically (45-15 total number) (0.49-0.13 per individual), and stayed about the same intraspecifically (38-49 total number) (0.42-0.42 per individual). The PTMG became less aggressive interspecifically (170-89 total number) (0.3-0.17 per individual), and more so intraspecifically (153-143 total number) (0.41-0.65 per individual). The results showed that forced resource partitioning does cause changes in the abundance and behavior of these species of hummingbirds.

• 

  Foraging habits and social learning of white-faced capuchin monkeys (Cebus capucinus), May 2010

  Jennifer E. Koska

  Foraging for food is an essential aspect to the life of Cebus capucinus. The transmission of this knowledge takes many months of careful observations and trial and error. I studied the foraging habits of C. capucinus in the Cloud Rainforest. It was predicted that there would be a difference between adults and juveniles. My data suggests that there is no difference in the foraging habits between adults and juveniles. These results suggest social learning during the juvenile phase of life impacts the foraging behavior of the C. capucinus.

• 

  Greater diversity of fungi on Atlantic slope of Costa Rican cloud forest, May 2010

  Joshua Obermeyer

  Biodiversity in much of the Neotropics is impacted by windward/leeward effects. North East trade winds dump moisture as they hit the mountains, creating a wetter Atlantic slope, and a drier more seasonal Pacific slope. These factors often favor higher biodiversity for a given taxon on the Atlantic slope. Fungi were collected between the two slopes of the Monteverde Cloud Forest. A total of 130 fungi specimens were collected from 1550 meters on both slopes of the Continental Divide to 1750 m. As predicted, fungal species richness (Pacific = 24 species, Atlantic = 39 species), abundance (Pacific = 40, Atlantic = 90), and diversity (H’ Pacific = 1.55, H’ Atlantic = 3.44) were significantly higher on the Atlantic slope than on the Pacific. It was also found that the two slopes, though in close proximity, have almost entirely different fungal communities. The results indicate that the climatic factors of high precipitation and lower seasonality caused by windward/leeward effects greatly effect fungal species diversity and composition.

• 

  Habitat preference of Leptonema sp. (Trichoptera: Hydropsychidae) on tropical waterfalls, May 2010

  Aaron Hamm

  According to Wiggins & Mackay (1978), most Trichoptera live in cases that they have made; there are several species that attach their cases to rocks and feed from the current and others that live in the gravel of the stream. Still, there are others that are located in the areas behind rocks where there is not as much current; most Trichoptera are restricted to cool lotic waters (Wiggins & Mackay 1978b). With such variability in habitat choices available for Trichoptera, it is evident that wherever a habitat is chosen it needs to be the right one. In this study a species of Trichoptera called Leptonema sp. are surveyed to find if water speed across the three different regions of a waterfall effect their distribution. There was no relationship found between Leptonema abundance and height of the waterfall. When the abundance of Leptonema per rock was regressed with the surface area of the rock (mm3) no significant difference was found. When the abundance means for each region were compared there was no significant difference between the above and below region, however both of those regions were marginally different from the crest, which had the most individuals. It was concluded that the Leptonema prefer the crest region because it is there that the fastest water flow occurs. This study is important because it allows an area of tropical stream ecology that has been studied little, to be investigated. The conservation implications of this study are long reaching. The ability to examine streams for the presence or absence of certain macroinvertebrates offers an opportunity to test the water quality of untrammeled lengths of stream, as certain kinds are useful as indicator species.

• 

  Herbivory and alkaloid concentration in Cecropia obtusifolia (Cecropiaceae) trees with and without ants, May 2010

  Katherine A. Riha

  Herbivore damage greatly impacts a plant’s fitness, and because of this, plants have evolved various defenses. Cecropia obtusifolia has a facultative mutualism with Azteca ants. Selection could favor plants without ants to compensate in some way, like increasing concentrations of secondary compounds. In this study, percent herbivory and alkaloid concentration were measured in C. obtusifolia trees with and without ants in Monteverde, Costa Rica. Herbivory levels were low in both occupied (mean ± sd = 2.702 ± 2.139) and unoccupied (3.029 ± 3.662) trees, and no significant difference was found in the concentration of alkaloids (mean ± sd with ants = 0.57 ± 0.34, without ants = 0.63 ± 0.45). These results could be a consequence of the dry season.

• 

  How ecotourism is felt throughout the greater Monteverde region with an emphasis on local happiness, May 2010

  Hannah L. Findlay

  Within the last two decades, the zone of Monteverde, Costa Rica has been targeted by the tourism industry as an ideal destination for conservationists and adventure-seekers alike. This study investigates many of the potential cultural impacts (including changes in individual levels of happiness) brought upon by the drastic shift in the economic focus of the community from agriculture to tourism in the past 20 years. I conducted 100 face-to-face interviews, each consisting of 18 questions, in all major regions of the zone of Monteverde. Questions aimed to obtain demographic information as well as the participants’ attitudes towards ecotourism and their reported happiness (on a scale of zero to ten) as of 20 years ago and presently. The mean happiness 20 years ago was 8.28 (±2.12) and today’s average is 8.565 (±1.86). I searched for meaningful interactions among demographic variables (age, gender, education level, occupation, percentage of income from tourism, etc.) and reported happiness and did not find any statistically significant correlations. However, valuable conclusions can still be drawn from this overall lack of correlation between demographic data and reported happiness. A more detailed appraisal of individual responses demonstrates that the needs of locals are often conflicting with the needs of tourism which can have detrimental cultural implications. For this reason, additional studies are warranted to more carefully define how the specific effects of tourism affect specific aspects of local culture and happiness and quality of life of the locals.

• 

  Importance of environmental education and knowledge comparing grades 9-12 in Monteverde, Costa Rica and Middleton, Wisconsin, USA, May 2010

  Katie Wipfli

  Environmental education is not always a part of school curricula, particularly in the developing world, where population growth and environmental degradation are increase most rapidly. This study takes place in Monteverde, Costa Rica where three local schools with varying levels of environmental education were surveyed. I compared them to a high school in Middleton, Wisconsin to see how Costa Rica and the United States compare. A 20-question survey was used to measure environmental knowledge of students at each school. I found that environmental education is important. Environmental education was an important determinant of environmental awareness and knowledge. Environmental Education, as a curricular focus, boosted even poor to middle class Costa Ricans to levels beyond average Costa Rican students from the same community; to a level nearly equal to affluent expatriates and students in the suburban United States.

• 

  Non-vocal sounds produced by the wings of Inca doves, Columbina inca, and seasonal effects on communication behavior in Costa rican dry-moist lowland forest, May 2010

  Robert Niese

  Recent studies have shown that many birds communicate non-vocally using highly modified feathers in their wings. Several columbid species (pigeons and doves) are believed to produce these non-vocal sounds when they are alarmed and take-off in flight, conveying threat-related information to other birds. This study investigated the communicative significance of the buzzing wing-sounds created during the flight of the Inca dove in dry to moist lowland forest of the Guanacaste province of Costa Rica and characterized seasonal changes in communication behavior. Recordings of alarmed and non-alarmed flight were acoustically analyzed and used for playback experiments to determine if wing-sounds can convey threat-related information. Playback experiments revealed that Inca doves interpret information from the wing-sounds of other individuals just like they interpret information in the coos of rivals. Responses to wing-sounds were significantly different than responses to coos, indicating that they convey a different kind of information. Wing-sound analysis could not confidently identify Inca dove wing-sounds as whistles or claps, instead suggesting wing-buzz as a more accurate descriptor. Additionally, changes in the seasons significantly affected the behavior of Inca doves, increasing territoriality and courtship behaviors during regular activities and in response to played-back coos. Seasonal changes in the response to wing-sounds could not be fully characterized. Several Inca dove nests were also discovered and characterized, finding that birds prefer to nest in trees and shrubs with thorns to deter nest predation.

• 

  Optimal energy allocation and behavior modification in provisioning Crawfordapis luctuosa, May 2010

  David Gardner

  Behaviors and actions of species can be described according to optimality. Crawfordapis luctuosa, an understudied endemic species to Central America, has little information pertaining to its behavior. Energy allocation can provide insight on what actions are most important to C. luctuosa. Measured times spent inside and outside provisioned nests indicate that manipulations involving the covering of nests influence these times. Optimal energy allocation for behaviors observed during a manipulation are noted and studied. Different behaviors could account for the amount of provisioning the bee needs to maintain. Further research on cost/benefit analyses and C. luctuosa could better describe the natural history and behavior of the species and other insects of the Order Hymenoptera.

• 

  Polyethism in Eciton burchellii army ants: a look at task specializations of worker castes, May 2010

  Colleen Nell

  Insect societies, specifically Eciton burchellii army ants have had high ecological success due to polyethism within the colony. This division of labor within the colony increases efficiency and therefore fitness of the colony, which has selected four morphologically and behaviorally defined castes; majors, submajors, media, and minims. Samples of these castes show strong division of labor and roles throughout the colony. Majors are shown to restrict themselves to the column and bivouac where defense is of highest necessity. Submajors have morphologically evolved to carry large prey and maintain column flow. Media are found to be generalists, reinforcing essential functions of the colony, and the smallest caste, minims play key roles within the structure of the bivouac and bridging for prey transport. Collectively these roles increase the efficiency of the colony and contribute to the ecological success of E.burchellii.

• 

  Responses to prey size in Metabus gravidus (Araneae: Araneidae) provide evidence for optimal foraging, May 2010

  Sunjana Supekar

  Foraging strategy is a critical factor in the fitness of many organisms. The optimal foraging theory states that animals optimize their fitness by selecting food that will provide the most amount of nutrition for the least amount of time and energy spent obtaining food. By minimizing energy spent on foraging, organisms can focus on other activities that benefit them, such as watching for predators, looking for mates, or caring for offspring. Because spiders have a very unique method of predation, they are a useful model organism for the study of optimal foraging. Metabus gravidus (Araneae: Araneidae) is a species of tropical orb-weaving spider common in Monteverde, Costa Rica. They forage by selecting and attacking prey that enter their orb-webs (Buskirk 1975). I investigated optimal foraging in these spiders by throwing moths of different sizes into spider webs and observing the spider responses. I found that spiders were more likely to attack smaller, more manageable moths, while larger moths typically elicited negative responses. These results suggest that M. gravidus prefer smaller sized prey, because they receive more nutrition for much less effort than the pursuit of larger prey would necessitate.

• 

  Shade coffee farms as conservation tools: A measure of butterfly diversity in coffee agroecosystems in the Monteverde Region of Costa Rica, May 2010

  Katie Thompson

  Costa Rica has experienced a history of high deforestation rates and has become a focus for the region’s conservationists. Coffee agro-ecosystems have recently been considered options for combining biodiversity conservation with economic development in the country. There has been debate over how sufficient shade-grown coffee farms are at maintaining biodiversity levels comparable to those of a forest. In this study, I surveyed butterfly richness, abundance, and diversity in a shade-grown coffee plot, a sun-grown coffee plot, and a secondary forest plot. There was a significant effect of location on number of butterfly species caught daily (F=3.81, P=0.03, df=2). Moving from shade to sun plots showed a decrease in butterfly diversity. There was a significant difference in diversity (H’) found between the sun and shade plots (P<0.05, df=118), but there was no significant difference in diversity (H’) between the shade-grown plot and the forest (P>0.20, df=122). This study suggests that, in order to conserve more biodiversity, sun-grown coffee farms should switch to shade-grown farms.

• 

  Site fidelity and song rate as indicators of territoriality in neotropical cricket (Gryllidae), May 2010

  Hannah Bergemann

  Territoriality is a competitive behavior expressed commonly throughout the animal kingdom in a wide variety of ways. To establish there is territoriality in simpler animals such as insects the practice of two specific types of behavior is a strong indicator. The first behavior is site fidelity, or the tendency of an animal to regularly return to previously occupied locations. The second behavior is the expression of aggression during encounters between two individuals in the presence of the aforementioned location. To test the presence of territoriality in a Neotropical cricket population, site fidelity was recorded as well as the response to an ‘intruder’s’ call being played in an individual’s territory. The results of these experiments confirmed the presence of territoriality in the subject, indicated by a high percentage of site fidelity and the reduced song-rate in the response call to intruder playbacks.

• 

  Sleep site selection in three species of Norops lizards (Squamata Polychrotidae) in the San Luis Valley, Puntarenas, Costa Rica, May 2010

  Peter M. Gibson

  The sleeping patterns of animals are important factors in fully understanding their behavior. I studied the sleeping site selection of three species of Norops lizards. I caught the lizards during the day, applied fluorescent powder, and tracked them to their eventual sleeping location at night using UV light. I measured multiple variables, including weather conditions, height, and level of protection provided by the site. Mean night heights of males and females, as well as among species, proved significantly different, thus maintaining daytime stratification. However, males and females were distributed opposite of that seen during the day, with females sleeping higher than males. Additionally, there were significant differences in protection preference across sex and species divisions, as only males and one species showed no preference for protected sites. Weather effects, such as precipitation and temperature, failed to show significance. Therefore, it appears that sex and species differences are the strongest factors driving sleeping site selection. Males seem driven more by sleeping site height, while females demonstrated greater desire for protection. Overall, the lizards were found to have a preference for protected sites.

• 

  Supernormal stimulus as a mimicry strategy the case for Epidendrum radicans (Orchidaceae), May 2010

  Daniel Paul

  Epidendrum radicans is a food deceptive Batesian mimic of its sympatric model species Asclepias curassavica and Lantana camara. Theoretically, food deceptive orchids should be rare with small inflorescences (Johnson et al. 1993; Weins 1978) yet in San Luis, Costa Rica E. radicans grows in large monotypic stands with individuals sporting up to 12 open flowers per inflorescence. E. radicans might attract pollinators using flower or inflorescence size as a visual supernormal stimulus also implicated in floral mimicry (Scheistl 2004). Pollinia removal of E. radicans was measured in plants with i) inflorescence sizes of two and ten growing amongst model species in patches ii) inflorescence sizes of one through eight flowers on plants growing naturally in dense stands without models and iii) unmodified and enlarged flowers. Pollinia removal was proportionally greater for flowers of smaller inflorescence sizes, and greater for unmodified flowers. E. radicans does not appear to use visual supernormal stimuli to attract pollinators. E. radicans may occur in large monotypic stands as a result of human disturbance. Continued pollinia removal in E. radicans may result from constant recruitment of naïve pollinators to the area.

• 

  The wag-display of the blue-crowned motmot (Momotus momota) as a predator-deterrent signal, May 2010

  Elise Nishikawa

  The blue-crowned motmot (Momotus momota) is a large, omnivorous, Neotropical bird. Momotus momota demonstrates a variety of life history traits that could make the bird more vulnerable to ambush predators as well as adaptations to signal to, and deter attack by, ambush predators. Like other motmots, M. momota performs an exaggerated tail-wagging motion when presented with a visual predatory stimulus. I studied the different reactions elicited by four treatments to examine the importance of the signal receiver as a predator that had been visually located by the motmot. I presented either an avian model or an avian call played back to motmots and observed reactions. Motmots were significantly more likely to wag-display (p = 0.0009) upon seeing an ambush predator, more likely to not interrupt normal behavior like foraging when presented with a non-predatory control call, and subjects never approached either predator stimulus trial. These results support the previous research that suggested that motmots wag-displayed to deter predation.

• 

  Alteration of crickets songs due to competition via playbacks, November 2009

  Katie Ehlers

  In many animal species, females do not mate randomly but rather they choose males based on their courtship signals. With crickets, calls may not be used soley for attracting a mate; they can also be used to reduce a competitor’s reproductive success. It was thus predicted that crickets would both respond to playbacks in an attempt to compete with the singing male and also alter their song in some way when singing competitively. Two different playbacks were created with one having a single cricket’s song and the other having a cricket chorus, and individuals received each treatment to determine its affect of their signal. Results show that the crickets did in fact change their song with respect to the number of elements per song and the rate of the song. It was concluded that crickets respond the same to one cricket as they do to many crickets; the number of crickets used for a given playback did not affect the individual’s likelihood to respond.

• 

  Altitudinal soil continuums of andisols on the Atlantic slope of the Tilaran Mountain Range (Costa Rica), November 2009

  Tyler Reynolds

  Presently, little is known about soils along an altitudinal gradient on the Atlantic Slope of the Tilarán Mountain Range in Costa Rica, so soil samples were taken and horizons were measured, on altitudinal transects from 1700m to 1300m in elevation. Precipitation patterns, decomposition rates, litterfall rates, temperature, and soil parent material depth, are recognized as playing important roles in the % soil root mass and nutrient cycles of tropical mountain soils. This study looks to find trends between these soil formation and maintenance factors, and altitude. These data present significant positive correlations of soil Nitrate-N and Phosphorus concentrations with elevation, and significant negative correlation of Potassium concentrations and pH with elevation. No significant correlation was found between % root mass and elevation due to high local and regional ecosystem heterogeneity. These discoveries lay the ground work for future comparative studies that will likely show the effects of climate change and land alteration practices on mountain rainforest soils.