The behaviour of two butterfly species, a habitat specialist (
Speyeria idalia
) and a
habitat generalist (
Danaus plexippus
), was tracked at four prairie edges to determine
the extent to which edges act as a barrier to emigration. The four edge types studied
were crop, road, field and treeline. The edges differed in structure ranging from highcontrast
(treeline) to low-contrast (field).