The Red Admiral butterfly (Vanessa atalanta, Lepidoptera: Nymphalidae) is a true seasonal migrant: an evolutionary puzzle resolved?

Abstract

Abstract. Ornithologists in Finland recorded the autumn migration of the Red Admiral butterfly, Vanessa atalanta (L.). In the best year, 1998, 1240 migrants were counted from a bird tower in September. That is, half a million butterflies migrated over a 100-km front. The butterflies were flying above forests riding on cool northerly winds. Radar indicated that a large proportion migrated at high elevations outside the visible range. These records help to resolve an "evolutionary puzzle" of why migrant butterflies and moths travel to northern latitudes when their offspring have limited possibilities of returning south. Until now, the only butterfly for which a high-elevation return migration on northerly winds is known is the American Monarch Danaus plexippus (L.).

The year-round phenology of the migratory Red Admiral Vanessa atalanta (Lepidoptera: Nymphalidae) in a Mediterranean area in southern Spain

“…In addition, these movements are of a continental scale and recorded in both Europe and North America (condition 2, see references above). Furthermore, the year-round phenology is highly predictable and was recorded year after year in the same area in this study (see Results, condition 3) and fi nally, the arrival and redistribution of Red Admirals at different overwintering sites in this study occurred simultaneously at least in the areas studied (condition 4, this study, see also Mikkola, 2003).…”

“…This year-round phenology is remarkably similar to that reported by Stefanescu (2001) at another Mediterranean site in north-east Spain. In fact, this seems to be the general trend at low latitudes as Red admiral imagoes are absent, or very rare, in summer (see also Gargallo Macías, 2014) but very common in autumn and winter (see also Pollard & Yates, 1993;Stefanescu, 2001;Mikkola, 2003;Brattström et al, 2008;Cuadrado, 2013;Fernández-Haeger et al, 2014;Fox et al, 2015; this study).…”

“…Stefanescu, 2001;Mikkola, 2003;Brattström et al, 2008;Lundmark, 2010; see also Bitzer, 2016 and references therein for a similar pattern recorded in the Nearctic). In the study area, the peaks of abundance recorded coincide with the progressive arrival of migrant butterfl ies in autumn (from September to November), a lower number of imagoes in the mid-winter months (December-January) and a new peak in abundance due to the emergence of a new generation in late winter (February-March).…”

“…Available evidence indicates that Vanessa atalanta reproduces during autumn and overwinters (either as an imago or immatures) in the Mediterranean area (e.g. Stefanescu, 2001;Mikkola, 2003;Brattström et al, 2008 and references therein;Lundmark, 2010). Stefanescu (2001) provides clear year-round phenology data for Vanessa atalanta at several lowland sites in Catalonia (NE Spain).…”

Pest insect immigration warning by an atmospheric dispersion model, weather radars and traps

“…2002), with obvious loss of individuals from the population. Return migrations of butterflies and moths in the autumn to lower latitudes have also been observed (Mikkola 2003; Chapman et al. 2008).…”