The effect of patch distance, matrix type and experience on habitat perception and flight speed of two species of Heliconius butterflies

Abstract

The perceptual range of an organism is the distance at which landscape elements are recognised by it. Estimates of this sensory trait are relevant to understand how organisms recognise suitable habitat within fragmented landscapes. We investigated how the nature of inhospitable environments (matrix) neighbouring a forest patch and adult experience (lab‐raised naïve vs. free‐flying experienced adults) affect the perceptual range and flight speed of the forest butterfly species Heliconius erato and Heliconius melpomene. In field experiments, butterflies were released at various distances from the edge of the habitat patch. Flight orientation and speed were evaluated. In one experiment, wild‐caught individuals of H. erato and H. melpomene were released in two matrix types, a coconut plantation and an open field. In a subsequent experiment, lab‐raised naïve H. erato was released at the same site. Release distance was the best predictor of butterfly behaviour for the two species. Individuals released up to 60 m successfully oriented towards the habitat patch, indicating a perceptual range below 100 m. Flight speed was higher the closer a butterfly was released to the edge. Matrix type did not affect butterfly orientation within its perceptual range distance. We did not find a significant effect of experience on butterfly orientation. Our study shows that the perceptual distance of Heliconius is within the range of known estimates from other butterfly species. Within this range, and irrespective of matrix type and experience, individuals were capable of orienting towards their preferred habitat and at flight speeds that were related to the distance of release.