Species composition and dynamics in abundance of migrant and sedentary butterflies (Lepidoptera) at Gibraltar during the spring period

Keith J Bensusan,Charles E Perez,Piotr Tryjanowski,Piotr Zduniak,Rebecca Nesbit

doi:10.14411/eje.2014.057

Keith J Bensusan, Charles E Perez + Show 3 more

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https://doi.org/10.14411/eje.2014.057

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Abstract

In order to understand patterns of abundances of migratory Lepidoptera in southernmost Europe and contrast this with those of sedentary species, we studied butterflies surveyed along transects during three spring migration seasons at the Rock of Gibraltar. Overall, 2508 butterflies belonging to 19 species were recorded. Of these, the four most numerous species accounted for almost 88% of all individuals recorded. These were the migratory Clouded Yellow Colias croceus, Red Admiral Vanessa atalanta and Painted Lady Vanessa cardui, and the sedentary Common Blue Polyommatus icarus. There was a significant correlation between abundance of P. icarus and C. croceus. Furthermore, abundances of C. croceus and V. atalanta were correlated. The sometimes very high abundance of migratory butterflies at the study site could suggest that Gibraltar is a stopover site for butterflies migrating between Africa and Europe.

Highlights

The seasonal migration of a range of taxonomic groups within the Lepidoptera is a widespread phenomenon throughout the world (e.g., Williams, 1958; Dingle, 1996; Dingle & Drake, 2007)
The four most numerous species accounted for almost 88% of all individuals recorded; three of these, the migratory species Colias croceus, Vanessa atalanta and Vanessa cardui, accounted for 70% of all observations and V. cardui alone comprised 35% of all butterflies observed (Table 1)
Approximately 70% of individuals belonged to the three migrant species and Vanessa cardui alone accounted for 35% of observations

Summary

Introduction

The seasonal migration of a range of taxonomic groups within the Lepidoptera is a widespread phenomenon throughout the world (e.g., Williams, 1958; Dingle, 1996; Dingle & Drake, 2007). Butterflies (Rhopalocera) usually migrate closer to the ground than moths (Taylor, 1974; Walker, 1985; Srygley & Oliveira, 2001) because wind speeds are lower here than their own airspeed, making it possible to control their track direction relative to the ground (Dingle & Drake, 2007). This, combined with their diurnal habits, makes them ideal for visual studies on migratory insects. Further research is required to study African aspects of the African-Eurasian migratory flyway (e.g., Stefanescu et al, 2013) and sites along this flyway as, unlike with Monarch Butterflies Danaus plexippus in North America (Davis & Garland, 2004; Meitner et al, 2004; Brower et al, 2006; McCord & Davis, 2010, 2012; Davis et al, 2012), migrant butterfly stopover has received very little attention in the Old World, even though suitable study sites exist

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