The role of dispersal in range change in birds

摘要: Eurasian reed warbler Acrocephalus scirpaceus expanded its range in Great Britain the late 20th and early 21st centuries. The role of dispersal this expansion was investigated. Inference mechanisms underlying dynamics drew on fieldwork, analysis large observational datasets, a simulation model; model run reedbed map Britain, generated from satellite data using machine learning. Breeding season temperature sets up warbler’s limit directly, by influencing occupancy current year, perhaps mediated through Phragmites australis phenology. Although components productivity were positively related to temperature, these adult survival did not decline edge. There therefore no evidence that demography plays limiting Britain; however, all aspects Survival negatively simulations suggested may allow maintain more northerly than without such relationship. Reed can be explained gradual equilibration with climate space, enabled long-distance dispersal: only rare dispersing individuals matched rate expansion. Reed edge tracked change, but bulk population lagged behind. This could due dispersal-limitation, or newly established populations grow too slowly generate sufficient emigrants. Simulations size is sensitive dispersal. number fledglings per breeding attempt increased over time, probably warming, have emigration; if so, cause rapid movement centroid later study period. Emigration, transition immigration play different roles space time.