An American Invasion of Great Britain: The Case of the Native and Alien Squirrel (Sciurus) Species

摘要: : The invasion of Great Britain by the gray squirrel from America has posed many interesting problems in ecology and conservation (interactions with native red squirrel) forest management (the severely damages young stands deciduous trees). Since 1973, mapped data on annual distribution two species state-managed forests have been published Forestry Commission. Using established methodology ornithological index numbers, series numbers calculated to show distributional dynamics species. In as a whole there rather limited change over 15-year period 1973. However, this masks (1) dramatic decline Wales balanced modest expansion Scotland, (2) substantial increase small number grid squares Scotland comparison relatively steady large England. A new index, measuring replacement one other species, indicates little overall England but net advance Wales. A Markovian matrices predicted that would persist some areas England, be rare Over whole, is likely occur about twice squirrel. Resumen: La de la Gran Bretana por ardilla gris proveniente ha planteado muchos problemas interes en ecologia y conservacion (interaccion con roja nativa) manejo forestal (la dana severamente parcelas jovenes arboles caducifolios). Desde 1973 comision publicado mapas sobre distribucion anual las dos especies bosques administrados el estado. Empleando metodologia establecida indices numericos ornitologicos anuales, se han calculado una serie para mostrar dinamica los cambios especies. nivel habido solo un cambio limitado dentro del periodo 15 anos desde Sin embargo, esto enmascara dramatica declinacion Gales, compensado modesta Escocia, substancial incremento reducido numero cuadros reticula comparado relativa estabilidad gran Inglaterra. Un nuevo indice, que mide remplazo unu especie otra, indica poco general Inglaterra pero avance neto Gales. Una Markovianas predijeron persistiria Escocia algunas Inglaterra, deberia ser rara Sobre su conjunto, es probable presente aproximadamente doble forestales roja.