title: Analysis of three amphibian populations with quarter-century long time-series.
abstract: Amphibians are in decline in many parts of the world. Long tme-series of amphibian populations are necessary to distinguish declines from the often strong fluctuations observed in natural populations. Time-series may also help to understand the causes of these declines. We analysed 23-28-year long time-series of the frog Rana temporaria. Only one of the three studied populations showed a negative trend which was probably caused by the introduction of fish. Two populations appeared to be density regulated. Rainfall had no obvious effect on the population fluctuations. Whereas long-term studies of amphibian populations are valuable to document population declines, most are too short to reveal those factors that govern population dynamics or cause amphibian populations to decline.
authors.affiliation: Institut für Umweltwissenschaften, University of Zürich, Switzerland. andrea.meyer@bfs.admin.ch
authors.forename: A H
authors.initials: AH
authors.lastname: Meyer
authors.forename: B R
authors.initials: BR
authors.lastname: Schimidt
authors.forename: K
authors.initials: K
authors.lastname: Grossenbacher
mesh_terms: D000818:Animals; D002980:Climate; D005399:Fishes; D005843:Geography; D010507:Periodicity; D011156:Population Density; D011891:Rain; D011896:Rana temporaria / Q000502:physiology; D012098:Reproduction / Q000502:physiology*; D013557:Switzerland