M. Kuussaari et al., AN EXPERIMENTAL-STUDY OF MIGRATION IN THE GLANVILLE FRITILLARY BUTTERFLY MELITAEA-CINXIA, Journal of Animal Ecology, 65(6), 1996, pp. 791-801
1. We studied factors affecting emigration and immigration behaviour i
n the butterfly Melitaea cinxia by releasing 882 newly emerged marked
butterflies into 16 habitat patches in a network of 64 empty patches o
n an isolated island (area 1.6 km(2)). 2. Of the 363 butterflies that
were recaptured at least once, 40% were recorded in a new patch during
their lifetime. Females emigrated earlier and moved further away than
males. One-third of males appeared to remain permanently in, whereas
females gradually drifted away from, the release patch. 3. High densit
y of butterflies, great abundance of flowers, and large patch area dec
reased emigration, whereas open landscape around the patch increased e
migration. Females that emigrated were on average larger than females
that stayed in the patch of release. 4. In total, 152 immigrants were
recorded in 32 patches. Numbers of immigrants increased with patch are
a and abundance of flowering plants. 5. Results on emigration suggest
that conserving an isolated butterfly population is more successful in
an area with physical barriers to migration than in an open landscape
. The possible tendency of butterflies to leave a patch with low densi
ty should be taken into consideration in introductions of butterflies
to empty habitat patches. 6. Results on immigration indicate the signi
ficance of nectar sources and patch size in successful colonization of
empty habitat patches.