Habitat preference and habitat exploration in two species of satyrine butterflies

Abstract

We compared the habitat preference and the mobility of different populations of primarily forest living, satyrine butterflies by observing them in a manipulated environment, containing different habitat types inside a large outdoor cage. The cage was 30 m long and divided into three parts. Each end of the cage contained a shady habitat, made to be similar to the floor of a forest with sunlit spots. In between these shady parts, there was a 14 m long open part, like a glade or a meadow. We performed two studies in the cage. In the first study, we compared a population of a species with very restricted distribution in Sweden, Lopinga achine, and a population of a widely distributed and expanding species, Pararge aegeria. We found that the two species had similar habitat preferences in the cage, but that L. achine had a lower rate of dispersal from one shady part of the cage to the other. In the second study, we compared two populations of P. aegeria, a Swedish forest living population and a Madeiran population inhabiting a fairly open habitat. We found that, although individuals of the Swedish population avoided staying in the open, middle part of the cage, they dispersed between the shady parts of the cage at a higher rate than individuals of the Madeiran population. We argue that studies of the kind we performed can serve the purpose of testing hypotheses about habitat preference and mobility that derive from other field work or from information about distribution patterns.