title: Weather explains high annual variation in butterfly dispersal.
abstract: Weather conditions fundamentally affect the activity of short-lived insects. Annual variation in weather is therefore likely to be an important determinant of their between-year variation in dispersal, but conclusive empirical studies are lacking. We studied whether the annual variation of dispersal can be explained by the flight season's weather conditions in a Clouded Apollo (Parnassius mnemosyne) metapopulation. This metapopulation was monitored using the mark-release-recapture method for 12 years. Dispersal was quantified for each monitoring year using three complementary measures: emigration rate (fraction of individuals moving between habitat patches), average residence time in the natal patch, and average distance moved. There was much variation both in dispersal and average weather conditions among the years. Weather variables significantly affected the three measures of dispersal and together with adjusting variables explained 79-91% of the variation observed in dispersal. Different weather variables became selected in the models explaining variation in three dispersal measures apparently because of the notable intercorrelations. In general, dispersal rate increased with increasing temperature, solar radiation, proportion of especially warm days, and butterfly density, and decreased with increasing cloudiness, rainfall, and wind speed. These results help to understand and model annually varying dispersal dynamics of species affected by global warming.
authors.affiliation: Natural Environment Centre, Finnish Environment Institute (SYKE), PO Box 140, 00251 Helsinki, Finland mikko.kuussaari@ymparisto.fi.
authors.forename: Mikko
authors.identifier: 0000-0003-0264-9316
authors.initials: M
authors.lastname: Kuussaari
authors.affiliation: Metapopulation Research Centre, Department of Biosciences, University of Helsinki, PO Box 65 (Viikinkaari 1), Helsinki 00014, Finland.
authors.forename: Susu
authors.initials: S
authors.lastname: Rytteri
authors.affiliation: Natural Environment Centre, Finnish Environment Institute (SYKE), PO Box 140, 00251 Helsinki, Finland.
authors.forename: Risto K
authors.initials: RK
authors.lastname: Heikkinen
authors.affiliation: Natural Environment Centre, Finnish Environment Institute (SYKE), PO Box 140, 00251 Helsinki, Finland.
authors.forename: Janne
authors.initials: J
authors.lastname: Heliölä
authors.affiliation: Lohentie 16, 06150, Porvoo, Finland.
authors.forename: Peter
authors.initials: P
authors.lastname: von Bagh
mesh_terms: D063147:Animal Distribution; D000818:Animals; D002080:Butterflies; D017753:Ecosystem; D011157:Population Dynamics; D012621:Seasons; D013696:Temperature; D014887:Weather
keywords: butterfly; climate change; dispersal; metapopulation; population dynamics; weather conditions