Betcha can't find an ecological use for ticks...I don't think anyone believes the fisher is a failed species just because it became locally extinct due to the destruction of it's habitat - by humans. Otherwise, there wouldn't be any fishers left to use for reintroduction. Like every other creature, they do have a place in the ecological system. Just ask those in the Pacific Northwest when they realized they were losing large portions of their forests due to porcupines after the fishers had been hunted out to "local extinction".