Movement across woodland edges suggests plantations and farmland are barriers to dispersal

Abstract

Context: The behavioural response of animals to edges between habitat patches and the matrix can influence population dynamics and species persistence in fragmented landscapes. Objectives: We aimed to answer two questions: (1) How do edge-effects between three land-cover types affect movement of adult male butterflies, and; (2) is response to edges influenced by perceptual range? Methods: In south-eastern Australia, we visually tracked the flight behaviour of the butterfly Heteronympha merope at edges between three land-cover types: native eucalypt woodland, farmland and exotic pine plantation. Using six replicates of each edge type, we released animals on both sides of the edges, and at two distances from the edge (5 m and 30 m). Results: Butterflies avoided pine edges, appeared to have low perceptual range in pines, and when released in pines, departed quickly. Butterflies often crossed from farmland into woodland and stayed, whereas none crossed from woodland into farmland or pines and stayed. Butterflies moved further away from pine edges when they were in woodland than when they were in farmland, suggesting edge-effects of one land-cover type depend on how animals respond to the alternative land-cover. Conclusions: Avoidance, and low perceptual range in plantations suggests plantations reduce landscape connectivity. Limited use of farmland is consistent with global reports that intensification of agriculture contributes to insect declines. Resource requirements of butterflies overlap with many other insects, and so extensive forestry plantations and intensive agriculture likely have negative impacts on a range of taxa, with improved land-sharing a possible solution. Show more