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Extreme weather events are becoming more frequent due to climate change. We therefore need to understand how species respond to these events. In 2018, the worst drought ever recorded hit the island of Gotland in the Baltic Sea, which led to a major decline of the threatened marsh fritillary (Euphydryas aurinia) the succeeding summer. We compared yearly occupancy among 256 habitat patches between 2018 and 2020 and analysed the colonisation-extinction dynamics between 2019 and 2020 in relation to patch area, connectivity, and habitat quality. Moreover, using capture-mark-release data in two patch clusters differing in connectivity, we also compared population sizes before and after the drought and analysed population growth rates. We also compared yearly abundance of host plants (Succisa pratensis) over time. Results show a remarkable recovery of the marsh fritillary. Both patch occupancy in 2020 and the number of individuals in the well-connected patch cluster were higher than before the drought. In contrast, host plants were fewer and smaller, which taken together suggest that the amount of food resources was roughly half in 2020 compared to the pre-drought conditions. Moreover, the butterfly population in the less connected patch cluster was eight times smaller compared to the population size before the drought. Local colonisations, extinctions, and population growth rates were explained by connectivity. The ability to quickly recover after extreme droughts is promising in times of climate change. The significance of connectivity for the population dynamics during recovery highlights the importance of maintaining well-connected patch networks. Funding Agencies|Cementa AB; Stiftelsen Oscar och Lili Lamms Minne [FO2020-0023]; Svenska Forskningsradet FormasSwedish Research Council Formas [2018-02846]

We used observational data collected during a mark-recapture study that generated a total of 7503 captures of 6108 unique individuals representing three endangered butterfly species to quantify inter-and intraindividual variation in temperature utilization and examine how activity patterns vary according to season, time of day, and ambient temperature. The Marsh Fritillary, the Apollo, and the Large Blue differed in utilized temperatures and phenology. Their daily activity patterns responded differently to temperature, in part depending on whether they were active in the beginning, middle or end of the season, in part reflecting interindividual variation and intraindividual flexibility, and in part owing to differences in ecology, morphology, and colouration. Activity temperatures varied over the season, and the Apollo and the Large Blue were primarily active at the highest available ambient temperatures (on the warmest days and during the warmest part of the day). The Marsh Fritillary was active early in the season and decreased activity during the highest temperatures. The relationship between individual lifespan and the average temperature was qualitatively different in the three species pointing to species-specific selection. Lifespan increased with an increasing range of utilized temperatures in all species, possibly reflecting that intra-individual flexibility comes with a general survival benefit. Funding Agencies|Cementa AB; Swedish Research Council for Sustainable Development, Formas [2018-02846]; Stiftelsen Oscar och Lili Lamms Minne [FO2020-0023]; provincial government of Gotland

Rapporten visar en GIS-baserad metod för att analysera konsekvenserna av befintlig infrastruktur för fladdermöss. Metoden har tillämpats för region Väst och visar konfliktpunkter och var skyddsåtgärder för fladdermöss, i form av nya passager, skulle göra mest nytta för fladdermöss.

Fladdermöss utgör 25 % av däggdjursfaunan. De har mycket långsam reproduktion och på grund av den stora förändringen i landskapet med anledning av fladdermössens val av främst föda och boplatser är hälften av de påträffade arterna sällsynta i Sverige. På grund av detta har alla arter ett starkt juridisk skydd. Denna rapport tar i huvudsak upp analys av främst skogslevande arterna som påverkas mycket negativt av vägar och järnvägar. Rapporten innehåller en beskrivning av GIS-verktyget PREBAT, som är en modellering över var i landskapet det finns stor sannolikhet att finna viktiga livsmiljöer, boplatser samt rörelsemönster för fladdermöss som bör undvikas eller där olika skyddsåtgärder bör genomföras för att minimera konflikter mellan fladdermöss och infrastruktur. Rapporten sammanfattar fladdermössens ekologi. Den beskriver vilket kartmaterial som används som ingångsmaterial i analysen och hur olika kartor som genereras i modelleringen tolkas. Slutligen beskrivs hur denna modellering kan användas för att kunna planera, bygga ny infrastruktur samt modifiera befintlig infrastruktur och ta hänsyn till fladdermöss. Bilagorna innehåller detaljerad information över olika ingångsvärden i modelleringen samt en detaljerad manual över de olika stegen.

Extreme weather events can be expected to increase in frequency in the future. Our knowledge on how this may affect species persistence is, however, very limited. For reliable projections of future persistence we need to understand how extreme weather affects species' population dynamics.We analysed the effect of extreme droughts on the host plant Succisa pratensis, colonization-extinction dynamics, and future persistence of the threatened marsh fritillary Euphydryas aurinia. Specifically, we studied a metapopulation inhabiting a network of 256 patches on Gotland (Sweden), where the summer of 2018 was the driest ever recorded. We analysed how the frequency and leaf size of host plants changed between 2017 and 2019, based on 6,833 records in 0.5-m(2) sample plots. Using turnover data on the butterfly from 2018 to 2019 we modelled local extinction and colonization probabilities. Moreover, we projected future population dynamics with an increasing frequency of extreme years under three different management strategies that regulate the grazing regime.Our results show a substantial decrease in both frequency (46%) and size (20%) of host plants due to the drought, which taken together may constitute a 57% loss of food resources. The butterfly occupancy decreased by over 30% between 2018 and 2019 (from 0.36 to 0.27). The extinction probability increased with increasing 'effective area' of the patch (taking quality reduction due to grazing into account), and the colonization probability increased with increasing connectivity and ground moisture.Projections of future dynamics showed an increasing risk of metapopulation extinction with increasing frequency of years with extreme droughts. The risk, however, clearly differed between management strategies. Less grazing in years with droughts decreased the extinction risk considerably.Synthesis and applications. Extreme weather events can have profound negative impacts on butterflies and their host plants. For the marsh fritillary, an increased frequency of extreme droughts can lead to extinction of the entire metapopulation, even in a large and seemingly viable metapopulation. Increased grazing, due to fodder deficiency in dry years, may lead to cascading negative effects, while active management that reduce grazing in years with droughts can almost completely mitigate these effects. Data are available via the Dryad Digital Repository https://doi.org/10.5061/dryad.s1rn8pk4k (Johansson, Kindvall, Askling, & Franzén, 2020).