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Stream site selection of Hyalinobatrachium fleischmanni (Centrolenidae)

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Title:
Stream site selection of Hyalinobatrachium fleischmanni (Centrolenidae)
Translated Title:
Selección del sitio de la quebrada de Hyalinobatrachium fleishmanni (Centrolenidae) ( )
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Book
Language:
English
Creator:
Ward, Alicia
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Subjects / Keywords:
Amphibians   ( lcsh )
Habitat selection   ( lcsh )
Costa Rica--Puntarenas--Monteverde Zone   ( lcsh )
Anfibios
Selección de hábitat
Costa Rica--Puntarenas--Zona de Monteverde
Tropical Ecology Fall 2004
Ecología Tropical Otoño 2004
Genre:
Reports   ( lcsh )
Reports

Notes

Abstract:
Census work and habitat analysis for the glass frog species Hyalinobatrachium fleischmanni was performed on four streams in Cañitas and Monteverde, Costa Rica. At each of six sites, the habitat occupied by H. fleischmanni was contrasted with a nearby, paired site where individuals were absent. Seven habitat parameters were investigated: water quality based on dissolved oxygen and phosphate content; water speed; discharge; distance from human development; extent of canopy cover; and presence or absence of common monocots (Zingiberaceae: Hedychium coronarium, Costaceae: Costus spp., Musaceae: Musa acuminata). No statistically significant differences were found between Occupied and Unoccupied locations though patterns suggested a preference for sites with faster water speed, greater discharge, and higher levels of dissolved oxygen. No gradients in group size based on habitat characteristics were observed. Population densities found in this study compared to densities reported by other sources and past studies showed an increase in density. This is especially significant in light of drastic frog population declines in past years in the Monteverde area.
Abstract:
Un censo y un análisis del hábitat de la especie de rana de vidrio, Hyalinobatrachium fleischmanni, se llevó a cabo en seis lugares de cuatro quebradas en el área de Cañitas y Monteverde, Costa Rica. En cada sitio, el hábitat ocupado por H. Fleischmanni se comparó con un lugar similar donde H. fleischmanni estaba ausente. Siete parámetros del hábitat fueron investigados: la calidad del agua basada en pruebas de oxígeno disuelto y fosfato; la velocidad del agua, la descarga, la distancia al desarrollo humano, la extensión de cubierta del dosel y la presencia o ausencia de monocotiledóneas comunes (Zingiberaceae: Hedychium coronarium, Costaceae: Costus spp., Musaceae: Musa acuminata). No se encontraron diferencias significativas entre las localidades ocupadas y desocupadas, aunque los patrones sugirieron una preferencia por los sitios con agua más rápida, más descarga y niveles altos de oxígeno disuelto. No hubo ningún gradiente en el tamaño de los grupos basado en las características del hábitat. En comparación a otras investigaciones, la población de ranas encontradas en esta investigación mostró un aumento de densidad. Este resultado es importante debido al declive de poblaciones de los años pasados en Monteverde.
Language:
Text in English.
General Note:
Born Digital

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University of South Florida Library
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University of South Florida
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All applicable rights reserved by the source institution and holding location.
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usfldc doi - M39-00387
usfldc handle - m39.387
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SFS0001556:00001


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Census work and habitat analysis for the glass frog species Hyalinobatrachium fleischmanni was performed on four streams in Caitas and Monteverde, Costa Rica. At each of six sites, the habitat occupied by H.
fleischmanni was contrasted with a nearby, paired site where individuals were absent. Seven habitat parameters were investigated: water quality based on dissolved oxygen and phosphate content; water speed; discharge; distance from human development; extent of canopy cover; and presence or absence of common monocots (Zingiberaceae: Hedychium coronarium, Costaceae: Costus spp., Musaceae: Musa acuminata). No statistically significant differences were found between Occupied and Unoccupied locations though
patterns suggested a preference for sites with faster water speed, greater discharge, and higher levels of dissolved oxygen. No gradients in group size based on habitat characteristics were observed. Population
densities found in this study compared to densities reported by other sources and past studies showed an increase in density. This is especially significant in light of drastic frog population declines in past years in
the Monteverde area.
Un censo y un anlisis del hbitat de la especie de rana de vidrio, Hyalinobatrachium fleischmanni, se llev a cabo en seis lugares de cuatro quebradas en el rea de Caitas y Monteverde, Costa Rica. En cada sitio, el hbitat ocupado por H. Fleischmanni se compar con un lugar similar donde H. fleischmanni estaba ausente. Siete parmetros del hbitat fueron investigados: la calidad del agua basada en pruebas de oxgeno disuelto y fosfato; la velocidad del agua, la descarga, la distancia al desarrollo humano, la extensin de cubierta del dosel y la presencia o ausencia de monocotiledneas comunes (Zingiberaceae: Hedychium coronarium, Costaceae: Costus spp., Musaceae: Musa acuminata). No se encontraron diferencias significativas entre las localidades ocupadas y desocupadas, aunque los patrones sugirieron una preferencia por los sitios con agua ms rpida, ms descarga y niveles altos de oxgeno disuelto. No hubo ningn gradiente en el tamao de los grupos basado en las caractersticas del hbitat. En comparacin a otras investigaciones, la poblacin de ranas encontradas en esta investigacin mostr un aumento de densidad. Este resultado es importante debido al declive de poblaciones de los aos pasados en Monteverde.
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Anfibios
Seleccin de hbitat
Costa Rica--Puntarenas--Zona de Monteverde
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Tropical Ecology Fall 2004
Ecologa Tropical Otoo 2004
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1 Stream site selection of Hyalinobatrachium fleischmanni (Centrolenidae) Alicia Ward Department of Biology, Seattle University Abstract Census work and habitat analysis for the glass frog species Hyalinobatrachium fleischmanni was performed on four st reams in Caitas and Monteverde, Costa Rica. At each of six sites, the habitat occupied by H. fleischmanni was contrasted with a nearby, paired site where individuals were absent. Seven habitat parameters were investigated: water quality based on dissolved oxygen and phosphate content; water speed; discharge; distance from human development; extent of canopy cover; and presence or absence of common monocots (Zingiberaceae: Hedychium coronarium Costaceae: Costus spp ., Musaceae: Musa acuminata ). No statistic ally significant differences were found between Occupied and Unoccupied locations though patterns suggested a preference for sites with faster water speed, greater discharge, and higher levels of dissolved oxygen. No gradients in group size based on habita t characteristics were observed. Population densities found in this study compared to densities reported by other sources and past studies showed an increase in density. This is especially significant in light of drastic frog population declines in past ye ars in the Monteverde area. Resumen Un censo y un anlisis del hbitat de la especie de rana de vidrio, Hyalinobatrachium fleischmanni se llev a cabo en seis lugares de cuatro quebradas en el area de Caitas y Monteverde, Costa Rica. En cada sitio, el hbitat ocupado por H. Fleischmanni se compar con un lugar similar donde H. fleischmanni estaba ausente. Siete parmetros del hbitat fueron investigados: la calidad del agua basada en pruebas de oxgeno disuelto y fosfato; la velocidad del agua, la de scarga, la distancia al desarollo humano, la extensin de cubierta del dosel y la presencia o ausencia de monocotiledneas comunes (Zingiberaceae: Hedychium coronarium Costaceae: Costus spp ., Musaceae: Musa acuminata ) No se encontraron diferencias signif icativas entre las localidades ocupadas y desocupadas, aunque los patrones sugirieron una preferencias por sitios con agua ms rpida, ms descarga y niveles altos de oxgeno disuelto. No hubo ningun gradiente en el tamao de los grupos basado en las cara cteristicas del hbitat. En comparacin a otras investigaciones, la poblacin de ranas encontrada en esta investigacin mostr un aumento de densidad. Este resultado es importante debido al declive de poblaciones de los aos pasados en Monteverde. Introdu ction Hyalinobatrachium fleischmanni is a small, nocturnal frog found on vegetation overhanging streams (Savage, 2002). Rather than being evenly spread out along the length of the stream, the males are usually heard calling from groups in patchy distribut ions (Mark Wainwright, personal communication). It is possible that these male aggregations form to attract females and that a site is selected for its conduciveness to signal propagation. More open habitat and elevated perches are shown to enhance acousti c effects of calls (Gerhardt, 1994). Calling leks would be more conspicuous to females and would provide them more mating options (Villegas and Wainwright, in

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2 press). It is also possible that a site is selected due to physiological requirements, and the bi otic and abiotic habitat parameters at that location are preferable to those at other spots. Anurans are sensitive to environmental quality since their skin is a breathing surface, and H. fleischmanni lays eggs on vegetation over streams so tadpoles can fa ll into the water (Savage, 2002). This aspect of life history relies on vegetation and water conditions being favorable for these stages of development. Previous studies have made many speculations as to the preferred habitat of H. fleischmanni groups A study on one stream in Monteverde observed H. fleischmanni to be very adaptable to disturbed areas with a partiality for altered forest riparian canopy versus pristine forest riparian canopy. It was also noted that the groups seemed to prefer fast moving s treams to slow ones and gingerlily (Zingiberaceae: Hedychium coronarium ) vegetation above other types of vegetation (Hayes, 1979). The author made these observations as side notes to the experiment taking place and suggested that further research would be needed to make any authoritative conclusions on these points. Other sources report findings that this species is tolerant of high levels of pollution ( http://www.redlist.org November 21, 2004). A detailed study spec ifically exploring factors of canopy cover, stream quality, vegetation types, and human impact could reveal if there are stream site selection preferences for H. fleischmanni groups. Hyalinobatrachium fleischmanni is one of the more commonly found anuran species in the Monteverde area and, as a result, has been studied to a fair extent. While listed under the category of Least Concern on the IUCN Red List ( http://www.redlist.org November 22, 2004), the situation in Monteverde provides a special case. Since research done by Hayes (1979) and others was conducted in Monteverde, drastic frog population declines have been reported here in the years 1987, 1994, and 1998 (Pounds et al., 1999). Data from past studies showed capture rates of H. fleischmanni ranging from 27 individuals in 18 hours (1.8 per hour; Jacobson and Werman, 1981), to 22 individuals in four hours (5.5 per hour; Buskirk et al., 1981), both on the Ro Guacimal below the Cheese Factory. By 1990, the popula tion on that same stretch of stream had disappeared and that section still remains unoccupied (Mark Wainwright, personal communication). In the greater Monteverde area, another source details that populations have declined from one male per meter of stream to a few males over several hundred meters (http://www.globalamphibians.org, November 22, 2004). Causes of decline have been speculated to be anything from global warming to chytridiomycosis or some combination of effects ( http://www.redlist.org November 22, 2004). The goal of this investigation was to census populations of H. fleischmanni on streams in the Monteverde area and observe biotic and abiotic factors of the habitat where groups were located in to see if a ny patterns exist. Seven specific habitat parameters were analyzed: dissolved oxygen content, phosphate content, flow rate, discharge, proximity to human development, extent of canopy cover, and presence or absence of common monocots (Zingiberaceae: Hedych ium coronarium Costaceae: Costus spp ., Musaceae: Musa acuminata ). It was predicted that H. fleischmanni groups would prefer faster moving streams with a greater volume of discharge. Less canopy cover was expected to be preferred, as well as the presence o f H. coronarium or similarly broad leafed vegetation. It was not known whether human development or water quality would have a negative impact on the groups. The population sizes found will be valuable to compare to

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3 previous data from before the large scal e declines and to determine habitat preferences to inform future conservation decisions. Materials and Methods Study Sites Five groups of H. fleischmanni in Caitas and one group in Monteverde were investigated. The study sites in Caitas were on the Qu ebrada Santamara, Quebrada Berros, and the stream parallel to the road to Las Nubes. The occupied locations will be referred to as Quebrada Berros 1 (accessed from the farm of Segundo Santamara), Quebrada Berros 2 (accessed from the highway to Abangares) Quebrada Santamara 1 (on the same side of the street as the Miramontes Hotel, accessed from the highway to Abangares), the Quebrada Santamara 2 (on the opposite side of the street as the Miramontes Hotel, accessed from the highway to Abangares), and Ca lle a Las Nubes. location studied, there was a corresponding Unoccupied location used on the same stream, selected by measuring a distance of at least 20 meters from the boundary of the Occupied location, upstream or downstream depending on which was least obstructed. The Unoccupied location was of approximately equal size as its paired Occup ied location. All sites were in the range of 1280 to 1370 meters of elevation within the Premontane Wet Forest Holdridge Life Zone (Haber, 2000). Censusing Fieldwork was done between October 28 and November 7, 2004. In order to census the populations o f H. fleischmanni groups were located on streams prior to the censusing period, and then maps were made of the area to facilitate counting. The censuses were performed between 1900 hours and 2130 hours and weather conditions including rain, wind, and moon were noted. Observations were made by walking in the streambed or closely alongside it. Calling individuals were marked on the site map, and the perch location in the vegetation was flagged with as much precision as possible to avoid recounting. Uncertai nties in the number of individuals in a specific location where calls were dense were noted. Habitat Analysis Fieldwork was done between October 28 and November 20, 2004. Data were collected on each stream during daylight hours after the censusing of th e group was completed. The length of stream occupied by the group was measured and boundaries were marked with flagging tape. An Unoccupied location was established based on the criteria discussed previously. One to three canopy density measurements were t aken using a canopy densitometer (Spherical Densiometer Model C) depending on whether the canopy cover in the site (Occupied or Unoccupied) varied greatly. Water quality was

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4 assessed according to two indicators: dissolved oxygen and phosphate. Two water samples were taken at each Occupied and Unoccupied location and the dissolved oxygen and phosphate content were measured in parts per million (ppm). Water speed was determined for each location by the amount of time it took a lemon to float three separate distances within that location and averaging the speeds. The discharge (the product of speed by width by depth) was calculated by measuring the width of the stream and average depth (based on three readings) at each spot the water speed was taken at and av eraging the three values. Distance from human development was measured starting at the bank of stream and measuring to the closest human construction. If the distance was greater than 100 meters, it was recorded as greater than 100 meters instead of an exa ct distance under the assumption that the distance was too great to have any differing effect on the frogs. Statistical Analysis Six of the seven factors (canopy density, dissolved oxygen content, phosphate content, average water speed, average discharge and distance from development) for which data were collected for Occupied and Unoccupied locations were analyzed using the Wilcoxon Paired Samples Test. Common monocots were analyzed on a presence or absence basis and did not require statistical analysis Results Hyalinobatrachium fleischmanni groups at Quebrada Berros 1 and 2, and Quebrada Santamara 1 and 2 were censused and found to contain group sizes of 15, 16, 36, and 45 males, respectively. Censusing lasted from one hour to one hour and 45 minut es with discovery rates between 8.57 individuals per hour to 30 individuals per hour. The average rate was 18.8 individuals per hour. The average density of individuals on these two streams was 0.79 individuals per meter. Males of H. fleischmanni were hear d calling in two sites were not censused due to weather conditions that caused the frogs to stop population size was estimated by local naturalist Mark Wainwright, who had extensive knowledge of the site. Based on the time of year, length of stretch of the stream used, and number of hours spent listening, the population was estimated to be ten indivi duals, assuming good weather conditions. No estimate was made for the Calle a Las Nubes stream. There was no apparent pattern between any of the habitat parameters and the resulting size of the group present in those conditions. The average water speed, di stance from development, and average discharge were the three parameters that showed variation among the groups (Figures 1 3). The extent of canopy cover, dissolved oxygen content, and phosphate content remained at nearly the same level among all groups.

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5 Figure 1. The number of individuals of H. fleischmanni males at each Occupied location as a function of average water speed. Figure 2. The number of individuals of H. fleischmanni males at each Occupied location as a function of distance from human dev elopment. Figure 3. The number of individuals of H. fleischmanni males at each Occupied location as a function of average discharge. > 100 m

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6 The Wilcoxon Paired Samples T est showed no significant differences between Occupied and Unoccupied paired locations for any of the habitat parameters. The test for dissolved oxygen content was inconclusive due to frequency of tied values. However, there is a trend that Occupied locati ons contained greater or equal dissolved oxygen content to their corresponding Unoccupied locations (Figure 4). Average water speed of paired Occupied and Unoccupied locations did not differ significantly (Wilcoxon Paired Test, T = 1.5, T + = 19.5, T = 0; Figure 5), nor did the average discharge of paired locations (Wilcoxon Paired Test, T = 3.5, T + = 17.5, T = 0; Figure 6). These factors showed Occupied locations having higher average water speed and discharge than Unoc cupied locations in all cases except one of the locations on the Quebrada Santamara. The difference between the Occupied and Unoccupied locations that varied from the trend was particularly small for the average water speed. Figure 4. Comparison of dissolved oxygen levels between Occupied locations of H. fleischmanni and Unoccupied locations at six sites. Occupied values are greater or equal to Unoccupied values. Figure 5. Comparison of average w ater speed between Occupied locations of H. fleischmanni and Unoccupied locations at six sites. Quebrada Santamara 1 is the only site where the Unoccupied location had a higher reported value though the difference between Occupied and Unoccupied bars is s mall.

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7 Differences in distance from human development were also inconclusive due to tied values between Occupied and Unoccupied locations at Quebrada Berros 1 (Figure 7). Figure 6. Comparison of average discharge between Occupied locations of H. fleischmanni and Unoccupied locations at six sites. Quebrada Santamara 2 is the only site where the Unoccupied location had a higher reported value. Figure 7. Comparison of distance from development between Occupied locations of H. fleischmanni and Unoccupied locations at six sites. > 100 m

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8 Phosp hate content analysis also provided inconclusive results due to tied values (Figure 8). The extent of canopy cover showed no difference between Occupied and Unoccupied paired locations (Wilcoxon Paired Test, T = 12, T + = 9 T = 0; Figure 9). Cover remained within a 20% range for all locations. The presence or absence of common monocots in each site was not analyzed statistically. While H. coronarium Costus spp. or M. acuminata were found at all sites (Appendix 1). In only one site, Calle a Las Nubes, was one of these monocots the dominant vegetation. H. coronarium was present in large quantities at the Occupied location of Calle a Las Nubes but was also present in the Unoccupied. In all other sites, the main vegetation was made up of larger trees forming a high canopy. There did not Figure 8. Comparison of phosphate content between Occupied locations of H. fleischmanni and Unoccupied location s at six sites. Figure 9. Comparison of percent canopy cover between Occupied locations of H. fleischmanni and Unoccupied locations at six sites.

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9 appear to be a relationship between the presence of these monocots and t he Occupied locations. Discussion Although analysis of the seven habitat parameters produced no statistically significant results, some interesting information can still be extrapolated. The results from the average water speed, average discharge, and d issolved oxygen show trends that can be related to the physiological requirements of the frogs and their life history. Tadpoles of H. fleischmanni develop in the stream water at the locations their parents select (Leenders, 2001), so qualities of the strea m at Occupied locations could be chosen by the parents to give their offspring a better chance of survival. Faster streams with greater discharge are more turbulent, which contrary to intuition, is actually better for the tadpoles. H. fleischmanni females lay their eggs on vegetation over the stream and when the tadpoles hatch, they drop from the leaves into the water. More turbulent water makes falling tadpoles less noticeable to stream predators waiting below, such as fish. Rain during hatching can also enhance this effect (McDiarmid, 1983). In most sites, the average water speed and average discharge were greater in the Occupied locations than the paired Unoccupied locations. This pattern is supported by previous findings from Hayes (1979) that faster fl owing streams were preferred by H. fleischmanni Selection of locations with faster water speed and greater discharge by adults could be a result of the survival needs of tadpoles. High dissolved oxygen content in the stream water could also be indicative of such parental behavior. Streams with elevated dissolved oxygen levels are healthier for tadpoles to develop in. Even though the results were statistically inconclusive, the trend showed that the Occupied locations had either greater or equal dissolved o xygen content to that at the paired Unoccupied locations (Figure 4). It is possible that adults choose locations by streams with greater dissolved oxygen content to lay their eggs. Further research might support this observation. There are limitations to t he reliability of the water test results due to the level of accuracy provided by the test kit used. It is possible that with a more accurate kit, the data from the water quality analysis would have shown statistically significant results. Content in ppm w as determined by matching the color of the water sample after a tablet was dissolved in it to a color scale on a laminated card. Variability in light levels during readings could possibly have affected the content reported. Previous studies on Quebrada Ber ros and Quebrada Santamara measured levels of dissolved oxygen in percent saturation and found content to be relatively high (Buckman, 2003; Payne, 2003). While percent saturation is not directly comparable with content in ppm, both scales agree that diss olved oxygen levels in these streams are elevated, lending support to the trend observed in this study. Results from the phosphate test showed neither a preference for high or low phosphate levels. The presence of phosphate in Occupied locations does show that tadpoles and adults are most likely tolerant of this pollution, as other sources have pointed out ( http://www.redlist.org November 21, 2004). Phosphate levels reported in this investigation varied little or not at all among samples, but other studies on both Quebrada Berros and Quebrada Santamara have shown levels of phosphate present

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10 (Buckman, 2003; Payne, 2003). Failure to detect differences could be due to the coarseness of the detection scale and the same l imitations as the dissolved oxygen test. Though distance from development, canopy cover, and vegetation type did not show clear trends like the last three parameters assessed, the lack of trend still provides information about H. fleischmanni y patterns. When male groupings are choosing the location along the stream in which to group, it seems that they might want to avoid human development due to the level of disturbance that comes with it, for example, increased noise, presence of domesticate d animals, and light pollution. The effect of distance from development in this study was shown to be inconclusive in its relation to Occupied and Unoccupied sites. Quebrada Berros 1 was greater than 100 meters away from the nearest human development at bo th its Occupied and Unoccupied locations, and so was assumed to be unaffected. For the remaining sites, all but Quebrada Berros 2 had Occupied locations farther from development than the paired Unoccupied locations. In other Monteverde sites not included i n the study it was observed that individuals were within three meters of human structures. This lack of a clear pattern in preference for distance from development corresponds with other sources that point to H. fleischmanni being tolerant of human develop ment ( http://www.redlist.org November 22, 2004). Vegetation and canopy cover could be very important to both adults and tadpoles in their physiological requirements. Adult males spend most of their time during mati ng season perched on vegetation directly over the water (Leenders, 2001) and females select males to mate with based in part on their perch site (Villegas and Wainwright, in press). Tadpoles hatch out of their eggs on the leaf surface and from there must m ake it into the water. While previous studies suggest altered canopy and H. coronarium are preferred by H. fleischmanni (Hayes, 1979), the results of this investigation show an opposite trend where all Occupied locations had high canopy densities and low o ccurrence of monocots. The extent of canopy cover in all Occupied and Unoccupied locations ranged from approximately 80% to 96%. Although there appeared to be a pattern in presence of broad leafed monocots in this study, this vegetation type was not the mo st common type at any of the sites with the exception of the Calle a Las Nubes stream. There was no significant difference between Occupied and Unoccupied locations for either canopy cover or monocot vegetation, and therefore these parameters fail to expla in the selection of one location over another. It is clear that altered, less dense canopy and broad leafed monocots in the vegetation are not a necessity for H. fleischmanni groups since Occupied locations were found without them. The fact that none of t hese parameters showed statistically significant results could mean that other theories for the location of a male group provide a better explanation. One of the theories previously mentioned was that males simply group out of leking behavior. Habitat para meters at multiple locations on the stream might be equally acceptable, but males group in one location in order to make themselves more available to females. Another possibility is that certain locations enhance signal propagation. Calling entails high en ergetic costs to an individual male, so locating habitat that augments acoustic effects would be preferable. Some factors that affect sound propagation include open areas, certain plant leaves, atmospheric turbulence via wind or warm air pockets, high avai lable perches, and interfering objects (Gerhardt, 1994). Groups may form in locations where calls are more enhanced and therefore less energy is

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11 expended. Neither the leking nor the acoustic theories exclude habitat selection for physiological needs, and i t is very likely that there is a combination of these factors determining site selection. Valuable information was gained in this study outside of analysis of habitat parameters. Censusing of four groups on two streams, Quebrada Santamara and Quebrada Ber ros, produced higher discovery rates than the capture rates reported from studies by Jacobson (1981) and Buskirk (1981) pre dating the population declines of H. fleischmanni in Monteverde. This can be expected since the census in this study only involved c ounting individuals by call and not physically locating each one. Other sources reporting on declines in Monteverde described population sizes as a few males over several hundred meters (http://www.globalamphibians.org, November 22, 2004). Censusing done f or this study has shown that on at least two streams in the Monteverde area, population sizes have reached greater densities. The groups found on the remaining streams used in this study were also observed to contain good sized populations though exact cou nts were not taken. Both the Quebrada Berros and the stream by the Calle a Las Nubes contained other groups of H. fleischmanni that were not studied. Other streams in Monteverde not analyzed in this investigation were also found to contain groups of H. fle ischmanni, these additional streams and groups located within the study area. Calling rate of the males drops significantly or ceases altogether when there are dry weather conditions, heavy rain, strong wind, or bright moonlight (Leenders, 2001; Villegas and Wainwright, in press). During the last week of the study period, winds reached a great enough force that no individuals were calling on any of the streams in the study area. In addition, there was a three day dry period that substantially decreased air humidity. The combined effects of wind and drought made it impossible to census the remaining two sites analyzed in the study or any additional streams. Continued work on these streams and other streams in the area might support the finding that H. fleischmanni has been able to successfully recolonize areas where its numbers were previously low. The R o Guacimal was not analyzed, but future studies might investigate why the stretch below the Cheese Factory remains uninhabited by this glass frog species. In summary, this study showed some patterns in habitat preference of H. fleischmanni though none were statistically significant. With more research, average water speed of streams and average discharge could be shown to be preferred by groups of H. fleischmanni Water quality tests performed at finer scales might show a preference for high dissolved o xygen levels and a tolerance for phosphate levels. It is unlikely that monocots are a prerequisite for occupied habitat, though detailed analysis of vegetation types could produce some patterns in preferred tree species and canopy cover. Distance from huma n development seems unlikely to be an influence on habitat choice based on this study as well as past studies. Detailed information on group sizes at four locations in the Monteverde area and additional information for sites not censused was presented in t his study. Much speculation exists as to the causes of population declines of H. fleischmanni in the past and to the recolonization in recent years. It is heartening to see that populations of H. fleischmanni in at least some areas of Monteverde are rebuil ding. More knowledge of how to protect these frogs and their habitats is needed if the population is to continue its upward trend in Monteverde.

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12 Acknowledgements I would like to thank all the families and businesses that allowed me to use the streams on their property. Thanks to Karen for answering my constant questions and giving great for inspiration. Also, thank you to all the people that proofed my paper. A specia l thanks to Mark Wainwright for suggesting this project, for all the detailed information, and for coming all the way out to Caitas on a bad frogging night. Literature Cited Buckman, A. 2003. Algae as biological indicators of stream water quality in Mo nteverde, Costa Rica. CIEE Tropical Ecology and Conservation Spring 2003: 314 324. Buskirk, R.; M. Fuller; T. Garland; S. Jacobson; D. Krempels; K. Nishikawa; S Werman. 1981. Parental care in glass frogs. OTS Tropical Biology 81 3: 254 257. Coloma, L .A.; Ron; Wild; Cisneros Heredia; Sols; Ibez; Santos Barrera. 2004. Hyalinobatrachium fleischmanni In: 2004 IUCN Red List of Threatened Species. < www.redlist.org >. Accessed 2004 November 22 Gerhardt, C. 1994. The evolution of vocalization in frogs an d toads. Annual Review of Ecology and Systematics, 25: 293 324. Haber, W. 2000. Plants and vegetation. In: Monteverde Ecology and Conservation of a Tropical Cloud Forest. N. Nadkarni (Ed.). Oxford University Press, New York, New York: 42. Hayes, M. 197 9. A comparison of life history parameters of two species of glass frogs. OTS Tropical Biology 79 3: 415 421. IUCN, Conservation International, and NatureServe. 2004. Global Amphibian Assessment. . Accessed on 2004 October 22. Jacobson, S; S. Werman. 1981. Reproductive biology of glass frogs. OTS Triopical Biology 81 3: 304 308. Leenders, T. 2001. A Guide to Amphibians and Reptiles of Costa Rica. pp 68 69. Distribuidores Zona Tropical, Miami, Florida: 305 pp. McDiarmid, R. 1983. Centrolenella fleischmanni In: Costa Rican Natural History. D. Janzen (Ed.). The University of Chicago Press, Chicago, IL: 389 390.

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13 Payne, S. 2003. Water quality and lichen coverage in Monteverde streams. CIEE Tropical Ecology and Conservation Spring 2003: 326 335. Pounds, A.; M. Fogden; J. Campbell. 1999. Biological response to climate change on a tropical mountain. Nature, 398: 611 615. Savage, J. 2002. The amphibians and reptiles of Costa Rica. pp 357 373. The University of Chicago P ress, Chicago, IL: 934 pp. Villegas, A; Wainwright. In Press. The calls of Costa Rican frogs.

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14 Appendix FROG GROUPS LENGTH GINGER STREAM ELEVATION CENSUS OF SECTION PRESENT TRAMONTI'S 1370 10 13.7 m NO QUEBRADA BERROS 1335 15 20.1 m NO FINCA (Costus) QUEBRADA BERROS 1280 16 25.6 m NO CALLE (Banana) QUEBRADA SANTAMARA 1350 36 42.7 m NO SAME SIDE (Costus) QUEBRADA SANTAMARA 1350 45 52.7 m NO OPPOSITE SIDE (Costus) CALLE A LAS NUBES 1350 N/A 17.2 m YES NO FROG GROUPS DISTANCE AWAY LENGTH GINGER STREAM ELEVATION FROM GROUP OF SECTION PRESENT TRAMONTI'S 1370 > 20 m N/A NO UPSTREAM QUEBRADA BERROS 1335 > 20 m (28.8) 20.2 m NO FINCA UPSTREAM (Costus) QUEBRADA BERROS 1280 20 m 2 3.2 m NO CALLE DOWNSTREAM (Banana) QUEBRADA SANTAMARA 1350 20 m 39.2 m NO SAME SIDE UPSTREAM (Costus) QUEBRADA SANTAMARA 1350 20 m 52.3 m NO OPPOSITE SIDE DOWNSTREAM (Costus) CALLE A LAS NUBES 1350 20 m 6.1 m YES DOWNSTREAM