OLYMPIA— It looks like a harmless, uplifting way to end a wedding ceremony, but the popular practice of releasing mail-ordered butterflies could leave a legacy of lasting damage, Washington Department of Fish and Wildlife (WDFW) biologists warn.
The biologists' chief concern is that released butterflies could decimate their native counterparts here by introducing disease, competing for food and altering survival behavior by interbreeding with them.
Many of the state's native butterflies already are under pressure because their native habitat is vanishing– one species already is on the state's endangered species list, another is recommended to be added to the list of threatened animals and 12 more are candidates for state protection listings.
"This activity has the potential to do a lot of damage, and I don't think the people doing it realize that," said Ann Potter, a WDFW wildlife biologist.
Released butterflies generally are mail-ordered or purchased over the Internet from out-of-state dealers, and may originate from far-flung locations in North American or abroad. Businesses are supposed to have a state Department of Agriculture permit in order to sell them to state residents. In addition, a WDFW permit is required to release wildlife–and that includes butterflies. The Department must evaluate the potential damage such releases can cause.
Ceremonial butterfly releases are a relatively recent but increasingly popular custom. In addition, mail-ordering butterflies for students to raise and release is becoming a staple of schoolroom science projects.
Releasing non-native animals of any kind teaches a poor lesson, Potter said, because their effect on the local environment is unpredictable and potentially devastating.
Examples abound of non-native fish, animals and plants which overrun their new settings because they lack natural predators. Potter cites the case of the gypsy moth, introduced in Massachusetts in the 1800s by silk producers eager to improve the vigor and productivity of their silk worms. The introduced moth has gone on to cause widespread damage to forest land and has prompted widespread pesticide spraying.
Butterflies are especially vulnerable to introduced intruders because native butterfly populations are small and localized to specific areas. Introductions of even a few non-local butterflies of breeding age could "swamp" the natives, Potter said. Wild, migratory butterflies which spend part of the year here also could be harmed if they bred with introduced butterflies and their offspring lost their migratory instincts.