MILWAUKEE (AP) -- An effort started a decade ago to return the whooping crane to its original numbers in eastern North America seemed outlandish at the time but Operation Migration is still going strong.

Each year since 2001, workers in Wisconsin don crane-like costumes to raise chicks hatched in captivity. They then teach young cranes an annual migration route to Florida using an ultralight plane to lead the way.

There are now 104 birds in the flock, including 20 breeding pairs. The group is well on its way to accomplishing its goal of 125 self-sustaining birds, including 25 breeding pairs.

This year's flock of 10 Wisconsin birds left central Wisconsin on Oct. 9, led as usual by an ultralight. Late last week, they were in Illinois.