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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Selección del habitat de Turdus Falcaklandii y su rol sobre la dispersión de semillas de especies exóticas en bosques nativos de la Isla Robinson Crusoe / Habitat selection of Turdus Falcklandii and it's role over exotic species seed dispersal in native forest of Robinson Crusoe island

Meneses Álvarez, Luis Octavio January 2016 (has links)
Memoria para optar al título profesional de Ingeniero en Recursos Naturales Renovables / Los animales dispersores de semillas son especies clave para la reproducción y persistencia de especies de plantas nativas. Sin embargo, estos dispersores de semillas también juegan un rol opuesto al contribuir a diseminar semillas de especies invasoras hacia el bosque nativo, siendo aquel efecto perjudicial altamente dependiente del comportamiento de movimiento y selección de hábitat de estos animales. Aquí se evalúa como las decisiones de movimiento y selección de hábitat del Zorzal (Turdus falcklandii) lo convierten en un eficiente dispersor de semillas de la invasiva Mora (Rubus ulmifolius) dentro de pequeños parches remanentes de bosque nativo en la isla de Robinson Crusoe. Se usó telemetría para rastrear movimientos de escala fina de 16 zorzales durante el otoño austral. Se aplicó un Modelo de movimiento de puente Browniano (BBMM) para determinar la disponibilidad de hábitat a lo largo de cada ruta para cada zorzal. Se utilizó un modelo multiestado para determinar las probabilidades transicionales de moverse entre diferentes estados de hábitat, incluyendo la matriz de especies invasoras y parches de bosque nativo. Los zorzales tienden a estar dentro de los parches de bosque nativo, con frecuentes viajes hacia la matriz, pero retornando al bosque después de pocos minutos. Este comportamiento del movimiento sugiere que los zorzales se alimentan de mora dentro de la matriz, llevando sus semillas dentro de los parches de bosque nativo, favoreciendo el establecimiento de especies invasoras.
2

Breeding Ecology and Migratory Connectivity of Passerines in the World's Southernmost Forests

Jara Millar, Rocio Fernanda 05 1900 (has links)
In the extensive and remote sub-Antarctic forests of South America, birds are the dominant terrestrial vertebrates. Despite considerable efforts to understand the ecology of birds breeding in these forests, our current knowledge for many species is still incomplete. During three breeding seasons (2014 – 2017), I studied the breeding ecology of the five most abundant open-cup forest-dwelling passerines in the sub-Antarctic forest of Navarino Island, Chile (55°04′S, 67°40′W). There were differences in some of the breeding strategies used by birds breeding on Navarino Island versus conspecific populations breeding at lower latitudes. Milvago chimango was the main nest predator of open-cup nesting forest passerines, and the main cause of nest failure. In addition, I found that species built their nests in sites with higher density and taller understory; however, these two factors decreased their nest survival. This mismatch could be due to a change in depredation risk on Navarino Island, and thus, passerines breeding there may be in an ecological trap. In addition, using light-level geolocators, I determined that the migratory connectivity of Elaenia albiceps is weak as a result of the large spatial spread of individuals on the wintering ground, and that the distances among individuals on the breeding grounds are not maintained in the wintering grounds. My study opens further questions about the mechanisms driving differences in breeding strategies among populations. In addition, further research is needed to assess hypotheses that could explain the mismatch between nest-site selection and nest survival and to understand what drives elaenias' movements, not only during winter but throughout their annual cycle.

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