Garden structure and small-scale corridors: routeways for butterflies

摘要

Garden habitats are susceptible to rapid and frequent change in content and structure, resulting in an extreme structural diversity within a relatively small area. Recording of butterfly flight paths over several seasons in a suburban garden in Wolverhampton showed that this structural diversity acted to channel individuals into a few locations, with implications for the distribution of butterfly individuals in the garden. Importantly, gaps in the structure of the immediate surroundings channelled the entry and exit of individuals into the garden. Most of the observed butterflies flew low enough to exploit these gaps and were therefore directly affected by the horizontal and vertical complexity of the garden. Gaps between large trees, over outbuilding areas, and the area immediately next to the house exterior (within 0-3 metres) were the main channels. Residence times in all parts of the garden were low, often <5 seconds, suggesting that gardens are used as part of a larger meta-corridor being exploited by individual butterflies migrating across urban areas, or searching for more specific resources. Careful management of structure and planting to actively concentrate or diversify the flight paths could effectively, and beneficially, manipulate these flight patterns and residence times on a garden-to-garden basis.