The nature of migration in the red admiral butterflyVanessa atalanta: evidence from the population ecology in its southern range

Abstract

Summary 1. The migrant Vanessa atalanta (L.) occurs throughout Europe and North Africa. In autumn, populations emigrate from northern and central Europe to the Mediterranean region to overwinter. In the spring, the northern range is recolonised by migrants from the south. The dynamics of the species in the winter range is poorly known. 2. From 1994 to 1999, adults and immatures of V. atalanta were monitored all year round in Mediterranean habitats in north‐east Spain. 3. Data showed that the Catalonia lowlands is an area to which V. atalanta migrates to breed during the winter. Migrants arrive in October and early November and initiate a period of intensive breeding. Larval development occurs throughout the winter until a first annual generation of adults appears in early spring. 4. Most of the butterflies emerging in the spring emigrate and leave the area without breeding. The data suggest strongly that recolonisation of the northern range is by these butterflies not by wintering adults. Altitudinal migration also seems to be a common phenomenon, allowing a further summer generation of adults to occur at high elevations within the Mediterranean region. 5. The complex phenology of V. atalanta in its southern range has evolved as a strategy to track larval resources through space and time. Autumn migration coincides with the greatest availability of the main food plant, Urtica dioica L. Late spring migration occurs by the time food quality is decreasing.

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

“…By comparing the time of the peak migration in Finland (Mikkola, 2003) with that of the peak arrival of butterflies in Spain in the same year (Stefanescu, 2001), it appears that the Red Admirals needed around five weeks to fly the 3000 km from Northern Europe to the Mediterranean.…”

“…The flights of the Red Admirals at low elevations against the wind, frequently observed in Central and Southern Europe (Stefanescu, 2001;Tucker, 1997;Benvenuti et al, 1994), and of Monarchs in North America (Gibo, 1986), possibly occur when suitable tailwinds are lacking.…”

“…When the Red Admirals leave Spain, the summer drought has started and the nettles are withering (Stefanescu, 2001). In Fin land in early June, when the main migration arrives, the nettles are growing rapidly.…”

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

“…Some trees were remarkably old (> 25 m tall and > 150 years old). The animal enclosures were surrounded by While these studies examine the migratory status of Red Admirals in the Palearctic, little is known about the yearround phenology of this species in southern sites around the Mediterranean Basin (but see Stefanescu, 2001). Available evidence indicates that Vanessa atalanta reproduces during autumn and overwinters (either as an imago or immatures) in the Mediterranean area (e.g.…”

“…Abbot, 1951;Urquhart & Urquhart, 1977;Opler & Krizek, 1984;Stefanescu, 2001;Holland et al, 2006;Dingle & Drake, 2007;Stefanescu et al, 2007;Chapman & Drake, 2010;Bitzer, 2016). For Vanessa cardui, a number of interesting fi eld studies provide new insights into the long distance migration between Africa and Europe and provide evidence of breeding and mass emer-time, ambient temperature, cloud cover (on a scale of 0 to 8) and wind speed (using 0-5 on the Beaufort scale) were noted fi rst at the beginning and then at the end of the transect (cf.…”