Instituto Internacional en Conservación y Manejo de Vida Silvestre

URI permanente para esta comunidadhttp://10.0.96.45:4000/handle/11056/14849

El Instituto Internacional de Conservación y Manejo de Vida Silvestre (ICOMVIS)genera y transfiere conocimiento y forma recurso humano mediante la investigación, educación y extensión en el campo de la conservación y manejo de vida silvestre y su relación con el ser humano en el Neotrópico, a través de acciones inter y multidisciplinarias que integran aspectos teóricos y prácticos para la conservación de la vida silvestre.

Contáctenos:

Página web: www.icomvis.una.ac.cr

Correo: icomvis@una.cr

Teléfono: (506) 2277-3922

Examinar

Mostrando 1 - 20 de 93

A comparison of fruit removal in Ficus colubrinae between birds and Ectophylla alba (Chiroptera: Phyllostomidae) in a Costa Rican rain forest
(Taylor and Francis Ltd., 2021-02-02) De la Llata Quiroga, Edna; Ruedas, Luis; Mora, José Manuel
Ectophylla alba almost exclusively feeds on the fruits of Ficus colubrinae therefore significantly contributing to dispersal of its seeds. The objective of this research was to quantify the fruit removal of F. colubrinae by E. alba and compare it with that of birds in a F. colubrinae tree at the La Selva Biological Station, Costa Rica. We established seven quadrats randomly at different heights of the tree. We took photographs of each quadrat, quantified the fruits in each photograph, and compared the number of fruits removed during periods of high and low activity. The on-site persistence time of birds (9:05 min) was higher than that of E. alba (0.32 s). Birds removed more fruits (46) than E. alba (41). Birds defecated on site more times (13.08 feces per day) than E. alba (7.5 feces per day). Thus, E. alba is a more important seed disperser of F. colubrinae than are birds, because it persisted a short time at the feeding site, and consumed food beyond the individual trees’ canopies. Most importantly, by defecating during flight or away from the fruiting tree, E. alba disperse seeds some distance from the F. colubrinae tree, thereby contributes more effectively toward seed dispersal.
A new nesting record for the jabiru in Costa Rica
(Waterbird Society, 1998) Villarreal Orias, Johnny
I document the first nesting record of theJabiru (Jabiru mycteria) in "Los Guatuzos" forest floodplain, Alajuela province, Costa Rica. The active nest was located in March 1995 at 10°49'23.70"N and 84°47'23.20"W. The nest was 16m high in a 23m high silk-cotton tree (Ceiba pentandra) and contained three chicks. The zone is not protected and active lumbering is underway.
A Sensitivity Analysis of the Application of Integrated Species Distribution Models to Mobile Species: A Case Study with the Endangered Baird's Tapir
(Cambridge University Press, 2019-04-21) Schank, Cody J; Cove, Michael V; Kelly, Marcella J; Nielsen, Clayton K; Farrill, Georgina O; Meyer, Ninon; Jordan, Christopher A; González-Maya, Jose F; Lizcano, Diego J; Moreno, Ricardo; Dobbins, Michael; Montalvo Guadamuz, Víctor Hugo; Cruz Díaz, Juan Carlos; Pozo, Gilberto; de la Torre, J. Antonio; Brenes Mora, Esteban; Wood, Margot A; Gilbert, Jessica; Jetz, Walter; Miller A, Jennifer
Species distribution models (SDMs) are statistical tools used to develop continuous predictions of species occurrence. 'Integrated SDMs' (ISDMs) are an elaboration of this approach with potential advantages that allow for the dual use of opportunistically collected presence-only data and site-occupancy data from planned surveys. These models also account for survey bias and imperfect detection through the use of a hierarchical modelling framework that separately estimates the species-environment response and detection process. This is particularly helpful for conservation applications and predictions for rare species, where data are often limited and prediction errors may have significant management consequences. Despite this potential importance, ISDMs remain largely untested under a variety of scenarios. We performed an exploration of key modelling decisions and assumptions on an ISDM using the endangered Baird's tapir (Tapirus bairdii) as a test species. We found that site area had the strongest effect on the magnitude of population estimates and underlying intensity surface and was driven by estimates of model intercepts. Selecting a site area that accounted for the individual movements of the species within an average home range led to population estimates that coincided with expert estimates. ISDMs that do not account for the individual movements of species will likely lead to less accurate estimates of species intensity (number of individuals per unit area) and thus overall population estimates. This bias could be severe and highly detrimental to conservation actions if uninformed ISDMs are used to estimate global populations of threatened and data-deficient species, particularly those that lack natural history and movement information. However, the ISDM was consistently the most accurate model compared to other approaches, which demonstrates the importance of this new modelling framework and the ability to combine opportunistic data with systematic survey data. Thus, we recommend researchers use ISDMs with conservative movement information when estimating population sizes of rare and data-deficient species. ISDMs could be improved by using a similar parameterization to spatial capture-recapture models that explicitly incorporate animal movement as a model parameter, which would further remove the need for spatial subsampling prior to implementation. © 2019 Foundation for Environmental Conservation.
Abundance, habitat and body measurements of the rare Long-clawed Mouse (Pearsonomys annectens) in the coastal temperate rainforest of southern Chile
(Studies on Neotropical Fauna and Environment, 2012) Cádiz, Rodrigo; Figueroa R., Ricardo A.; Figueroa, Rodolfo; Soraya, Corales E.; Murúa, Roberto
Based on rodent trappings in eight localities from 1998 to 2005 (14,984 trap-nights), we provide detailed information on abundance, habitat and additional body measurements of the Long-clawed Mouse (Pearsonomys annectens), a rare rodent in the Valdivian temperate rainforest. The Long-clawed Mouse was collected in three localities only in both highly fragmented and continuous forests, including forestry plantations. The sites had relatively mature and closed vegetation and deep soils covered with leaf litter. Males appeared to be larger and heavier than females. Sexually active individuals were found in spring. We conclude that small and geographically restricted populations, low population densities, microhabitat specialization, and dependence on southern temperate forest make long-clawed mice vulnerable to the disappearance of the forest.
Abundancia del jaguar (Panthera onca), otros felinos y sus presas potenciales en el Parque Nacional Santa Rosa, Costa Rica / Abundance of jaguars (Panthera onca), other felids and their potential prey in Santa Rosa National Park, Costa Rica
(Universidad Estatal a Distancia, Costa Rica, 2015) Montalvo Guadamuz, Victor; Sáenz Bolaños, Carolina; Ramírez Carvajal, Shirley; Carrillo Jiménez, Eduardo
Abundance of jaguars (Panthera onca), other felids and their potential prey in Santa Rosa National Park, Costa Rica. Santa Rosa National Park, Guanacaste Province, protects one of the largest remnants of dry forest in Mesoamerica. It is considered an example of how to regenerate forest in an area that for many years was used for cattle. A proper management requires knowledge of trends in mammal populations. We chose species that demand high ecologic integrity. the jaguar (Panthera onca ) and other felines, and their potential prey. Using trace count we assessed abundance on seven trails systematically sampled in 2001 and later in 2011. In 2011 we found more traces of jaguars, less of cougars and the same number for ocelots. In the second sampling we found less herbivores and frugivores, and more omnivores. We believe that the trace method is reliable, rapid and cheap.
Abundancia, tamaño y estructura poblacional del tiburón punta blanca de arrecife, Triaenodon obesus (Carcharhiniformes: Carcharhinidae), en Bahía Chatham, Parque Nacional Isla del Coco, Costa Rica
(Universidad de Costa Rica, 2012) Zanella, Ilena; López Garro, Andrés; Golfín Duarte, Geiner; Sáenz, Joel
Approximately 12 species of shark inhabit at Coco Island National Park (PNIC); some are migratory, such as the hammerhead shark (Sphyrna lewini) and whale shark (Rincodon typus), and others are resident, like the whitetip shark (Triaenodon obesus). The whitetip shark is a species related to coral reefs, it inhabits coastal environments and is nocturnal and, it is very common in tropical waters, but there are few studies worldwide. In fact, only short researches have been done about their behavior at PNIC. Therefore, this study aimed to give data about the abundance, size and population structure of the whitetip shark at Chatham Bay in Coco Island National Park, providing baseline information for monitoring its population which is also very vulnerable to climate change. In order to accomplish this aim, a mark-recapture method was used, as well as underwater visual counts to determine their relative abundance and visual recaptures at Chatham Bay. The most effective hours for tagging were between 18:00 and 22:00 (sunset), when the whitetip sharks were more active probably related to foraging behavior. In addition, the depth was a relevant factor for tagging, sharks were caught in shallow water (10.9±1.9m). This species prefers to feed in shallow water and this behavior is probably related to the distribution and occurrence of rock and coral reefs in Chatham Bay. Based on the results, whitetip shark do not have a defined spatial ontogenic segregation, since in the same sites both juveniles and adults were found. The study confirmed that whitetip shark use specific residence sites: during the tagging trips, different individuals were recaptured; and during the underwater counts, at least 32.76% of tagged sharks were observed. The average length of the tagged sharks was 101.8±12.1cm (130.0cm maximum and 71.0cm minimum). The relative abundance of the whitetip shark in Chatham Bay observed was estimated on 49.5±10.4 sharks/hour. Furthermore, using the recapture data obtained during the night tagging expeditions, a population of 408 (IC = 181-1050) sharks was estimated.
Adaptación de indicadores de turismo sostenible: implementación en Chiapas, México
(Universidad de Costa Rica, Costa Rica, 2020-09-25) Rioja Paradela, Tamara; Camacho Ruiz, Edali; Carrillo Reyes, Arturo; Espinoza Medinilla, Eduardo; Porras Murillo, Laura
Este estudio adapta y propone una serie de indicadores de turismo sostenible, así como un índice de sostenibilidad turística. Se aplicaron indicadores cuantitativos y cualitativos en un centro turístico de Chiapas, México. De manera relevante se identifican los aspectos críticos que deben abordarse para incrementar la sostenibilidad, y se detalla indicadores que pueden ser utilizados por los administradores del sitio y otros proyectos turísticos similares
Agentes infecciosos en el zorro cangrejero (cerdocyon thous) en las áreas protegidas urbanas del Valle de Aburrá, Colombia
(Universidad Nacional, Costa Rica, 2021) Muñoz Mazo, Sara Salomé; Spínola Parrallada, Romeo Manuel
La detección de agentes infecciosos en animales de fauna silvestre en entornos urbanos es fundamental para su conservación y manejo. Dependiendo del tipo de agente infeccioso que los afecte, las implicaciones son relevantes tanto para su especie como para su entorno. El objetivo de este estudio fue identificar los agentes infecciosos en el zorro cangrejero (Cerdocyon thous) en las Áreas Protegidas Urbanas del Valle de Aburrá APU, Colombia. Se analizó la información obtenida de 24 zorros en las 6 Áreas Urbanas Protegidas APU y sus áreas de amortiguamiento. Entre febrero de 2020 y enero de 2021, se realizaron exámenes clínicos, se recolectaron muestras sanguíneas, materia fecal, orina y necropsias. Se recolectó la muestra fecal de 9 individuos, resultando 1 individuo positivo para huevos de Estrongilidos. En los resultados del laboratorio clínico (Hemogramas, citoquímico de orina, químicas sanguíneas) al no tener valores de referencia de la especie en el país, no es posible realizar una comparación de los valores obtenidos con los de referencia. Para la familia Anaplasmatacea, registré 3 (19%) resultados positivos en 16 muestras, 2 para Ehrlichia spp y 1 para Anaplasma spp. Para el agente Leptospira spp se procesaron 19 muestras con un resultado de 4 ejemplares positivos (21,05%). Los resultados encontrados son de importancia científica al ser el primer reporte de Leptospira interrogans por técnicas moleculares de análisis PCR en Colombia, la presencia de estos agentes infecciosos, indica la circulación de patógenos de importancia mundial por sus implicaciones en la salud pública, siendo un valioso aporte para las APU, llenando vacíos de información sobre el mamífero de mayor tamaño que las habitan y de esta manera poder adoptar medidas de manejo para su conservación.
Agroforestry systems conserve species-rich but modified assemblages of tropical birds and bats
(Springer, 2007-05-31) Harvey, Celia; González Villalobos, Jorge
Although an increasing number of studies have shown that diverse, multi-strata agroforestry systems can contribute to the conservation of tropical biodiversity, there is still debate about how the biodiversity within agroforestry systems compares to that of intact forest and alternative land uses. In order to assess the relative importance of agroforestry systems for biodiversity conservation, we characterized bat and bird assemblages occurring in forests, two types of agroforestry systems (cacao and banana) and plantain monocultures in the indigenous reserves of Talamanca, Costa Rica. A total of 2,678 bats of 45 species were captured, and 3,056 birds of 224 species were observed. Agroforestry systems maintained bat assemblages that were as (or more) species-rich, abundant and diverse as forests, had the same basic suite of dominant species, but contained more nectarivorous bats than forests. Agroforestry systems also contained bird assemblages that were as abundant, species-rich and diverse as forests; however the species composition of these assemblages was highly modified, with fewer forest dependent species, more open area species and different dominant species. The plantain monocultures had highly modified and depauperate assemblages of both birds and bats. Across land uses, bird diversity and species richness were more closely correlated with the structural and floristic characteristics than were bats, suggesting potential taxon-specific responses to different land uses. Our results indicate that diverse cacao and banana agroforestry systems contribute to conservation efforts by serving as habitats to high numbers of bird and bat species, including some, but not all, forest-dependent species and species of known conservation concern. However, because the animal assemblages in agroforestry systems differ from those in forests, the maintenance of forests within the agricultural landscape is critical for conserving intact assemblages at the landscape level.
Ámbito de acción, uso del hábitat y actividad diaria de la taltuza Orthogeomys heterodus (Rodentia: Geomyidae) en una zona hortícola de Costa Rica.
(Universidad Nacional, Costa Rica., 1994) Bonillo, Never
Home range, daily activity and habitat use of four Giant Pocket Gophers Orthogeomys heterodus were detennined by radiotelemetry. The study was carried out in a horticultural area of Cartago province, Costa Rica, during December 1989 and January 1990. Home range averaged 325 m2 for males and 233 m2 for females. There was a significant relationship between home range size and individual body mass. In average, 78 % of localizations were in the nest or refuge located in all cases in the border of crops. Activity was greatest from 0600 to 0800 h and 1200 to 1400 h, and was reduced at night.
Ambito de hogar y utilización de hábitat de dos grupos de venados Cola Blanca Odocoileus virginianus (Artiodactyla: Cervidae) reubicados en un ambiente tropical
(Universidad Nacional, Costa Rica, 1998) Vaughan Dickhaut, Christopher; Sáenz Méndez, Joel
Ocho venados cola blanca fueron liberados en la finca La Emilia, Guanácaste, Costa Rica, durante noviembre de 1987 y marzo de 1988. Cuatro hembras procedían de una población insular (Isla San Lucas, ISL) y habían sido criadas en cautividad hasta los 9 meses de edad cuando fueron liberadas. Los cuatro restantes eran adultos. Tres hembras y un macho del Parque Nacional de Palo Verde (PV). Todos los ciervos fueron marcados con collares de radiotelemetría y seguidos durante un periodo de 13 meses. Los cuatro ciervos de ISL también fueron observados directamente durante 8 meses. Se determinó y comparó el área de campeo y el uso del hábitat de cada grupo. El área de campeo media diaria fue de 18,3 ha para el grupo ISL y de 18,4 ha para el grupo PV; las diferencias entre estos valores no fueron significativas (Análisis de Varianza, ANOVA, P> .05). Las áreas de campeo de ambos grupos no fueron significativamente diferentes entre estaciones; sin embargo, el grupo ISL sí mostró una diferencia significativa entre ambas estaciones (ANOVA, P<0,05). El grupo ISL utilizó ocho tipos de hábitat de los 14 disponibles, mientras que el grupo PV utilizó 11 tipos de hábitat; se encontraron diferencias en las preferencias de hábitat entre ambos grupos (Xl P< .(01). La utilización del hábitat fue significativamente diferente entre los dos grupos tanto en la estación seca como en la húmeda (Xl, P< ,001). Los hábitats más utilizados (confianza intervais de Bonferroni) del grupo ISL fueron pastizales, plantaciones forestales (Pithecelobium saman), terrenos cliltivados (sorgo y frutales) y vegetación ribereña. El grupo PV utilizó hábitats con cierta cobertura forestal, chaparral, jaraguales y guacimales (Guazuma ulmifolia).
Analysis of the Interactions Between Humans and Crocodiles in Costa Rica
(Sociedade Brasileira de Herpetologia, 2020) Porras Murillo, Laura Patricia; Mata Cambronero, Erick
The habitat of crocodiles (Crocodylus acutus) and caimans (Caiman crocodilus) has been subjected to pressure due to human expansion. Habitat reduction, coupled with the simultaneous growth of the crocodile population, increases the number of interactions between crocodiles and humans. There is currently no official and systematized interactions database, but it is necessary to know the magnitude and nature of the interactions and establish management measures. The objective of the work was to systematize and evaluate the interactions between crocodiles and humans in Costa Rica. Historical information was collected from several sources. A total of 99 records, dated between 1990–2017, were found from press reports and the Integrated System for Processing Environmental Complaints of the Ministry of Environment and Energy (SITADA). The Fire Department recorded 123 events in 2017. All Fire Department records corresponded to encounters or sightings. Of the SITADA incident records, 35.4% were non-fatal, 27.3% were fatal, 21.2% were encounters and sightings, and the remaining 16.1% were miscellaneous situations. Most interactions occurred during the day, a fact potentially explained by human behavior of being in bodies of water or on adjacent shoreline while the sun is out. Most interactions occurred in the Central Pacific, followed by the Caribbean and then the South Pacific. The information available is brief but allows to establish management measures. The country needs to create a national database of interactions and to encourage individuals to report their interactions. Further research should continue to analyze the data for trends with the goal of building recommendations to prevent an increase in negative interactions.
Anthropization in buffer zones of protected areas
(Elsevier B.V., 2024-11) Moya Calderón, Michael; Barrientos Ávila, Enzo; Loría Chaves, Allan; Carrillo Jiménez, Eduardo; Barriocanal Lozano, Carlos
A nivel mundial, las áreas protegidas representan uno de los principales atractivos para visitantes nacionales e internacionales ( Bushell, 2003 ). Desde finales del siglo XX, el crecimiento turístico ha creado diferentes presiones sobre los espacios naturales, principalmente provocadas por cambios en el uso del suelo ( Boavida-Portugal, Rocha, & Ferreira, 2016 ). La modificación de un ecosistema a través de efectos antropogénicos se conoce como antropización ( Martínez, 2010 ). Uno de los factores que potencia esta problemática es la atracción de los territorios costeros por el turismo de sol y playa ( García-Ayllón, 2018 ). A través del aumento de áreas urbanizadas, mayor flujo vehicular, consumo de recursos naturales , aumento de la contaminación y presión sobre los espacios naturales, el turismo de playa y costero supone severas amenazas para el ecosistema ( Kim, Lee, & Kim, 2019 ).
Attitudes and interactions of indigenous and non-indigenous people with wildlife in the northern Talamanca mountains of Costa Rica
(University of Massachusetts Amherst, 2021-09) Sáenz-Bolaños, Carolina; Fuller, Todd K.
In this study I investigated wildlife and human use of landscapes in the northern Talamanca Mountains of Costa Rica (Pacuare-Barbilla sector), including three contiguous protected areas (a national park, a forest reserve, and an indigenous territory), as well as surrounding unprotected areas. I describe and compare perceptions of wildlife by different social actors in the Pacuare-Barbilla sector, collecting information with a questionnaire as an instrument. I also inventoried and monitored the abundance and distribution of a variety of wildlife species occurring throughout the area using camera traps. The species with greater abundance or only occurrence in the national park were mammals and birds commonly hunted, and species present in the forest reserve are species related with perturbed or human presences areas. The park and indigenous territory still keep good forest cover, as well as some important mammal species (e.g. jaguar, paca, red brocket, white-lipped peccary), despite high hunting rates. I also used these data to investigate the potential correlations of human behaviors with differences in biodiversity among different landscapes. A total of 91 questionnaires were applied and 59 wild species were reported by interviewees (33 mammals, 20 birds, 6 amphibian and reptiles); more species were reported by non-indigenous than indigenous interviewees. Moreover, the cited species cataloged as problematic because they attacked cattle, pigs, chickens, or pets, caused crop losses, and posed some risk for humans, were also higher for nonindigenous people. Jaguars and coyotes were cited most often as problem species by both groups. In particular, 68% of indigenous interviewees cited either jaguar or puma as causing attacks to their animals (pigs and cows mostly), with a total of eight species as poultry predators and six more as crops eaters. Both groups perceive less rainfall and higher temperatures, as well less forest cover and smaller jaguar populations, compared to 10 or more years ago. The feelings and attitudes about big cats changed in relation to how close people think they are or by their view of their negative impacts. Indifference and fear were the most named feelings, and relative intensity of feelings varied by ethnicity and gender. This geographical area is a very good example of how different regulations could result in differences in some mammal and bird species abundances and occurrences, and thus need to be considered when assessing the overall effectiveness of protection as a conservation strategy. Moreover, is necessary involve, learn from and work with local communities, especially concerning attacks on domestic animals, to better address conservation projects generating long-term benefits for humans and the wildlife.
Bush Dogs in Central America: Recent Range Expansion, Cryptic Distribution, or Both?
(SAGE Publications Inc., 2019-05-01) Sáenz-Bolaños, Carolina; Fuller, Todd; Mooring, Michael S.; Porras, Junior; Sievert, Paul R.; Carrillo, Eduardo; Montalvo, Victor H.
Bush dogs (Speothos venaticus) are a small, wide-ranging neotropical pack-hunting canid whose ecology is relatively poorly known. Here, we document new, repeated observations of bush dog groups in east-central (Barbilla National Park) and south-eastern (La Amistad International Park) Costa Rica that suggest either that their recent or historic range has been underestimated, or that their potential range in Central America may have recently expanded and could now include not only borderlands with Panama but perhaps a substantial portion of the Talamanca Mountains up to 120 km to the northnorthwest and at elevations up to 2,119 m. In light of their inherently low density, documenting the current and future distribution of bush dogs in Central America will be challenging
Camera trapping ocelots: An evaluation of felid attractants
(Hystrix, 2014) Spínola, Romeo; Cove Michael; Spinola, Manuel; Jackson, Victoria L.; Saenz Joel
Ocelots (Leopardus pardalis) and other wild cats are often surveyed using camera traps to identify individuals for density estimation via capture-recapture analyses or estimate occupancy via detection/non-detection analyses. Though attractants are sometimes used in such surveys, there have not been any evaluations of the effectiveness of common visual and olfactory attractants in field settings. As part of a medium and large mammal camera survey in the San Juan – La Selva Biological Corridor, Costa Rica, we integrated camera trap data within an occupancy modelling framework to estimate the effects of hanging compact disks (visual), cologne (olfactory), and sardines in oil (olfactory) on ocelot detection probabilities. Compact disks appeared to have the most information-theoretic model support, whereas cologne received less model support. The use of compact disks in surveys was also less time-consuming and less expensive than the olfactory attractants. Ocelots are visual hunters and using visual attractants can increase detection probabilities and therefore reduce uncertainty and/or reduce survey effort to obtain robust population or occupancy estimates, although using cologne might also have similar effects. Depending on logistic constraints, we recommend employing several attractants as the most appropriate way to survey ocelots and other rare felids in the future when detection biases are assumed to be strong, particularly as part of mammal community surveys.
Camera trapping ocelots: An evaluation of felid attractants
(Universidad Nacional, Costa Rica, 2014) Cove, Michael; Spinola, Manuel; Jackson, Victoria; Saenz, Joel
Ocelots (Leopardus pardalis) and other wild cats are often surveyed using camera traps to identify individuals for density estimation via capture-recapture analyses or estimate occupancy via detection/non-detection analyses. Though attractants are sometimes used in such surveys, there have not been any evaluations of the effectiveness of common visual and olfactory attractants in field settings. As part of a medium and large mammal camera survey in the San Juan – La Selva Biological Corridor, Costa Rica, we integrated camera trap data within an occupancy modelling framework to estimate the effects of hanging compact disks (visual), cologne (olfactory), and sardines in oil (olfactory) on ocelot detection probabilities. Compact disks appeared to have the most information-theoretic model support, whereas cologne received less model support. The use of compact disks in surveys was also less time-consuming and less expensive than the olfactory at tractants. Ocelots are visual hunters and using visual attractants can increase detection probabilities and therefore reduce uncertainty and/or reduce survey effort to obtain robust population or occu pancy estimates, although using cologne might also have similar effects. Depending on logistic constraints, we recommend employing several attractants as the most appropriate way to survey ocelots and other rare felids in the future when detection biases are assumed to be strong, particu larly as part of mammal community surveys.
El cerdo cimarrón (Sus scrofa, Suidae) en la Isla del Coco, Costa Rica: Composición de su dieta, estado reproductivo y genética
(Universidad Nacional, Costa Rica., 2001) Sierra, Claudine
Feral pigs (Sus scrofa) cause different kinds of damage specially on oceanic islands. Pigs were introduced at Cocos Island, Costa Rica, during 1793 and bred successfully. I analised feral pigs diet, reproductive state, genetics and the effects of predation, in order to gather data on their ecology and impact on certain Cocos Island communities. The diet was studied, during a dry and a wet period, through stomach contents. The genetic variability was determined through PCR analysis on tissue samples which were taken from feral (Cocos Island) and domestic (mainland) pig ear-lobes. Pigs at Cocos were omnivorous, the most important diet category in both seasons was fruits. More pigs consumed fruits during the wet season but the fruits did occupy more somach volume during the dry season. Feral pigs did not disperse exotic seeds nor prey on animal endemic species. 56 % of the hunted pigs were males and 44 % were females. From females in reproductive age, 46 % were pregnant or suckling, and the average number of fetuses in a litter was 4.4. I confirmed a reproductive peak during January/ February but could not demonstrate a reproductive peak during June/July. The low fetuses number per litter could be related with some levels of stress. The genetic variability for all the evaluated parameters within the feral population was low but not as low as expected. I suggest a compensatory mecanism were the inbreeding depression reduces consanguinity and a species sucptible to stocastic, demographic or environmental factors turns to be an adapted species with high resilience.
El cerdo cimarrón (Sus scrofa, Suidae) en la Isla del Coco, Costa Rica: Escarbaduras, alteraciones al suelo y erosión
(Universidad Nacional, Costa Rica., 2001) Sierra, Claudine
Feral pigs (Sus scrofa) are of the most damaging exotic vertebrates, specially on oceanic island nativecommunities. Feral pigs inhabit Cocos Island since 1793 and there are around 400-500 individuals. In order toquantify the impacts of the feral pigs at Cocos Island, I calculated the effect of the rooting activity and its influ-ence on the natural erosion. During one year I walked, monthly, 15 km on trails estimating rooted area by tran-sect and rooting recurrence. During eight months I compared erosion rates with and without rootings. I estimat-ed the annual rooting rate between 10 and 20 % of the total island surface. The rooted area was the only meas-ured variable which correlated with the soil erosion rate. The erosion rate without rootings was 23.6 kg/ha/yearand with rootings was 200.4 kg/ha/year (P < 0.01). The disturbances provoked by the rootings were not scatteredhomogeneously through the island. The rootings, together with the natural landslides, dominate the soil distur-bance pattern at Cocos Island. This study suggests that the presence of feral pigs produces more erosion than theone that would naturally occur without feral pigs at Cocos Island.
Cetáceos de las aguas costeras del Pacífico norte y sur de Costa Rica
(Universidad Nacional, Costa Rica., 2010) Martínez-Fernández, Damián; Montero-Cordero, Andrea; May-Collado, Laura
Cetáceos costeros del Pacífico Norte y Sur de Costa Rica. Veintinueve especies de cetáceos ocurren en aguas costarricenses pero sólo se han realizado investigaciones extensivas para tres especies. Esto último demuestra que hay una falta de información general y local sobre estos mamíferos, incluso cuando el país, ha mostrado un notable crecimiento en las actividades de observación de ballenas. El creciente uso de los recursos marinos en las zonas costeras también ha desarrollado la necesidad de determinar la ocurrencia de cetáceos en áreas de alta presencia turística, con el fin de proponer medidas de conservación adecuadas. En este estudio se determinaron las variables ambientales y posteriormente se relacionaron con la presencia de las especies registradas, de un total de 166 avistamientos, entre 2005 y 2006. Las especies con mayor proporción de avistamientos fueron Stenella attenuata (68%), seguida de Megaptera novaeangliae (13%) y Tursiops truncatus (10%). La presencia de delfines moteados está relacionada con los cambios en la salinidad y la transparencia del agua, mientras que la de la ballena jorobada estaba relacionada con la altura de las olas (escala de Beaufort) y la temperatura del agua. Se confirmó la presencia de siete especies de cetáceos en dos zonas costeras del litoral Pacífico de Costa Rica, de las cuales tres están presentes durante todo el año. Se encontraron variables ambientales relacionadas con la presencia de al menos dos especies.

Examinar

Examinando Instituto Internacional en Conservación y Manejo de Vida Silvestre por browse.metadata.procedence "Instituto Internacional en Conservación y Manejo de Vida Silvestre"