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Testing for density dependence allowing for weather effects |
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| Authors: | Peter Rothery Ian Newton Lois Dale Tomasz Wesolowski |
| Institution: | (1) Institute of Terrestrial Ecology, Monks Wood, Abbots Ripton, Huntingdon, Cambridgeshire, PE17 2LS, UK Fax: +44 (0) 1487 773 487, GB;(2) Department of Avian Ecology, Wroclaw University, Sienkiewicza 21, 50 335 Wroclaw, Poland, PL |
| Abstract: | A test for density dependence in time-series data allowing for weather effects is presented. The test is based on a discrete time autoregressive model for changes in population density with a covariate for the effects of weather. The distribution of the test statistic on the null hypothesis of density independence is obtained by parametric bootstrapping. A computer simulation exercise is used to demonstrate the gain in statistical power by allowing for weather effects. Application of the method to time-series data on three species of butterflies and two species of songbirds showed stronger evidence of density dependence than two standard tests. Received: 4 October 1996 / Accepted: 4 August 1997 |
| Keywords: | Density dependence Weather effects Autoregressive model Statistical power Butterfly and songbird populations |
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