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Abstract Estimating population dynamics and dispersal distances of owls from nationally coordinated ringing data in Finland.-Amateur bird ringers can collect data at a geographic and temporal scale that is rarely possible with professional field crews, thus allowing truly national analyses of popula...
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| Format: | Text |
| Language: | English |
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2004
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.1053.1612 http://www.bcn.cat/museuciencies_fitxers/imatges/FitxerContingut4411.pdf |
| Summary: | Abstract Estimating population dynamics and dispersal distances of owls from nationally coordinated ringing data in Finland.-Amateur bird ringers can collect data at a geographic and temporal scale that is rarely possible with professional field crews, thus allowing truly national analyses of population dynamics and dispersal. Since the early 1970s, bird ringers in Finland have been strongly encouraged to focus on birds of prey, especially cavitynesting owls. In addition to ringing nestlings and adults, ringers also provide data on population trends and breeding success. The resultant data indicate that numbers of breeding pairs fluctuated with the 3-4 year microtine cycle, but without any long-term trend. Mean productivity per nest varied from 2.18 to 3.33 fledglings per active nest in Tawny Owls, 1.56 to 2.87 in Ural Owls and 1.78 to 4.32 in Tengmalm's Owls. Survival and breeding propensity also varied with the vole cycle and explained much of the observed variation in breeding populations. Observed median dispersal distances were 24 and 18 km for Ural and Tawny Owls respectively, but increased to 36 and 48 km, using a method presented here to adjust for uneven sampling effort, highlighting the importance of considering sampling effort when estimating dispersal. Key words: Amateur ringers, Natal dispersal, Population modelling, Mark-recapture analysis, Tawny Owl, Ural Owl, Tengmalm's Owl. Resumen Estimación de la dinámica poblacional y de las distancias de dispersión en los búhos, efectuada utilizando datos de anillamiento de Finlandia coordinados a escala nacional.-Los anilladores aficionados pueden recopilar datos a una escala geográfica y temporal que rara vez está al alcance de los equipos de campo profesionales, lo que permite llevar a cabo análisis de dinámica poblacional y de dispersión de alcance verdaderamente a escala nacional. Desde principios de la década de 1970, se ha recomendado encarecidamente a los anilladores de Finlandia que se centren en las aves de presa, en concreto, en los búhos que ... |
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