Geographic origin and migration phenology of European red admirals (Vanessa atalanta) as revealed by stable isotopes

Abstract

BackgroundLong-distance migration has evolved multiple times in different animal taxa. For insect migrants, the complete annual migration cycle covering several thousand kilometres, may be performed by several generations, each migrating part of the distance and reproducing. Different life-cycle stages and preferred orientation may thus, be found along the migration route. For migrating red admirals (Vanessa atalanta) it has been questioned if they reproduce in the most northern part of the range. Here we present migration phenology data from a two-year time series of migrating red admirals captured at Rybachy, Kaliningrad, in the northern part of Europe investigating time for migration, life-history stage (migration, reproduction) as well as site of origin in individual butterflies.MethodsRed admirals were captured daily at a coastal site during spring, summer and autumn in 2004 and 2005. For the sampled individuals, reproductive status and fuel content were estimated by visual inspection, and hydrogen isotopes (δ2H) were analysed in wing samples. δ2H values was compared with samples from two nearby reference sites in Estonia and Poland.ResultsAnalysis of hydrogen isotopes (δ2H) in red admiral wings showed that the spring cohort were of a southerly origin, while those caught in August or later in the autumn were from the local region or areas further to the north. All females caught during spring had developing eggs in their abdomen, but no eggs were found in late summer/autumn. There was a male-biased sex ratio during autumn and a difference in lipid content between years. When comparing the isotopic data with inland nearby locations, it was clear that the range of δ2H values (− 181 to − 78) was wider at Rybachy as compared to the two reference sites in Estonia and Poland (− 174 to − 100).ConclusionsDuring spring, migratory female red admirals arrived from the south and were ready to reproduce, while the autumn passage mainly engaged local and more northern individuals carrying large fuel deposits in preparation for long-distance migration. The phenology data suggest that individuals select to migrate in favourable weather conditions and that numbers may differ between years. Future studies should focus on individual sampling at a wide range of sites to reveal differential migration strategies and timing of migration between sexes and populations of migrating butterflies.Electronic supplementary materialThe online version of this article (10.1186/s40462-018-0143-3) contains supplementary material, which is available to authorized users.

Dispersal and migration have contrasting effects on butterfly flight morphology and reproduction

“…Dispersal and migration are defined in various ways [17]. Based on common usage, we define migration as the seasonally cyclical, long-range (hundreds of kilometres) and unidirectional movement of populations over the span of weeks or months, with little feeding, as seen in milkweed butterflies and Vanessa atalanta [18][19][20]. By contrast, we define dispersal as the resource-driven, relatively short-range, non-cyclical and multidirectional movement of individuals or small groups over hours or days during which individuals may feed frequently, as seen in Catopsilia [21] and Euphydryas editha [22].…”

Long-distance dispersal of migrant butterflies to the Arctic Ocean islands, with a record of Nymphalis xanthomelas at the northern edge of Novaya Zemlya (76.95°N)

“…Vanessa atalanta and V. cardui are well-known seasonal long-distance migrant species that may successfully breed in boreal and subarctic areas (Bolotov 2002(Bolotov , 2004Bolotov et al 2013;Brattström et al 2018) with a subsequent backward autumnal migration of newly emerged adults to the lower latitudes (Williams 1935;Stefanescu 2001;Mikkola 2003a, b;Stefanescu et al 2017).…”

Stable isotopes in monitoring terrestrial arthropods

“…Natural abundance studies are used when the origin of migrants is unknown and other marking techniques are not applicable, or it is impossible to mark them (Brattström et al, 2018;Qin and Shi, 2020). The origin of migrants may also vary in time, which as such may be worth monitoring (Hobson et al, 1999).…”