MADISON, WI (WTAQ) - Nine Wisconsin baby whooping cranes will resume their migration trip to Florida, after the FAA granted a one-time waiver to let the flight continue.

The agency said the trip could resume because it was in, "mid-migration."

The baby cranes were following an ultra-light pilot to two winter nesting locations, as part of a decade-old project to increase the numbers of endangered cranes in the eastern U.S.

But the trip was grounded in Alabama in mid-December, after the group Operation Migration learned that it broke federal rules against paying pilots of sport aircraft like ultra-lights.

The group's attorney asked for a waiver in late December. And when it was granted Monday, the FAA said it would work with Operation Migration on a "more comprehensive, long-term solution."

Group co-founder Joe Duff said over 1,400 people signed online petitions urging the FAA to let the flight continue. And he said it was probably a record for getting Washington to approve a waiver.

Still, Duff said he understood that the FAA didn't want to, "open the floodgates" to risky uses of sport planes.