Demographic analysis of snake killing as a conservation threat: study case for a population of Ninia atrata

Abstract: Intentional killing has recognized worldwide as one of the causes of snake populations decline. However, the effects of intentional killing have been poorly studied, as well as conservation and management initiatives devoted to mitigate this threat. This doctoral thesis concerns about the...

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Autores:: Angarita Sierra, Teddy German

Tipo de recurso:: Doctoral thesis

Fecha de publicación:: 2018

Institución:: Universidad Nacional de Colombia

Repositorio:: Universidad Nacional de Colombia

Idioma:: spa

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Summary:	Abstract: Intentional killing has recognized worldwide as one of the causes of snake populations decline. However, the effects of intentional killing have been poorly studied, as well as conservation and management initiatives devoted to mitigate this threat. This doctoral thesis concerns about the demographic effects derivate from intentional snake killing on wild populations. Therefore, a population of the species Ninia atrata was employed as study case to evaluate hypothesis that the intentional snake killing has deep impact in the viability of populations. For this purpose, a population dynamic of Ninia atrata population that inhabit at oil palm plantation was modeled using an integral projection models (IPM) as demographic approach. Afterwards, the demographic responses of the model in front of different killing snake scenarios were assessed. To build the vital rates employed in the demographic model, a deep exploration of the Ninia atrata natural history traits was carried out. Particularly, the relationship between reproductive phenology, feeding ecology, and prey-predator interactions with biotic and abiotic factors such as climatic variability, seasonality, and food availability, were described in detail. As a result, it was clear that the pattern of intentional snake killing on agricultural landscape can be predicted from tasks developed by field workers. However, this pattern is affected by underlying factors such as the way in which field workers experienced fear, gender and educational level, rather than seasonality or climatic variability on snake abundances or richness. Besides, the population structure of the species is mainly composed by neonates, with a significant seasonal variability. Apparent survival rate showed a negative relationship with body mass suggesting that as the snake body mass increases, the chances of survival decreases. Recruitment and fecundity were the main demographic processes driving the population fate, in which heavy weighted snake individuals have the strongest contribution to long-term population size. Finally, the perturbation analyses showed that the intentional snake killing does not represent a significant threat to the viability of the Ninia atrata population under study. This suggests that short-lived tropical snake species with a fast life history strategy allocating a high reproductive effort at each of its few reproductive occasions are able to escape from this source of mortality

Demographic analysis of snake killing as a conservation threat: study case for a population of Ninia atrata

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