Assessing year-round phenology and reproduction of the migratory painted lady butterfly, Vanessa cardui (Lepidoptera: Nymphalidae), in a Mediterranean area in southern Spain

Abstract

The painted lady, Vanessa cardui (Linnaeus, 1758), migrates seasonally between Africa and Europe with a northward multigenerational migration from Africa to Europe in spring and a southward migration from Europe to Africa in autumn. However, little is known about the year-round phenology of this species in southern regions in the Mediterranean Basin. In this study the year-round phenology and reproduction of painted ladies was recorded during a seven-year period (2014-2020) at 7 lowland sites (< 80 m a.s.l) near the coast of Cádiz (southern Spain). Overall, a total of 2341 painted lady butterflies (or 0.56 butterflies/km) were recorded along 4186 km of transects of the Butterfly Monitoring Scheme (BMS). Data pooled for all sites and years indicate a migration of painted ladies in autumn (mid and late October), another peak in abundance in winter (late February) and finally a migration in spring (late May). Abundance, however, varied greatly between sites and years. In July 2019, a spectacular migration of painted ladies was recorded across the study area that was also recorded in other European countries a few weeks later. Territorial behaviour of males, including hill-topping and courtship, oviposition and immature stages were recorded in autumn and winter. Reproductive behaviour was not recorded in spring or summer. Painted ladies were most abundant during the autumn migration, less abundant in spring and much less abundant in winter. This study confirms that the southern tip of Western Europe close to North Africa is an important stop-over region during the migration of painted ladies although numbers fluctuate enormously between years and sites. To my knowledge, this is the first time that the timing of year-round migration and the reproduction of painted ladies in the autumn-winter months have been described for a southern European population.

Keywords

• lepidoptera
• nymphalidae
• vanessa cardui
• migratory butterflies
• phenology
• winter reproduction
• mediterranean area
• spain