WASHINGTON — Georgetown University ecologist Emily Williams first became fascinated with birds not because of their beauty, or their sweet songs. She was riveted by their extraordinary travels.

WASHINGTON — Over the past 18 months, 29 prisoners have escaped from federal lockups across the U.S. — and nearly half still have not been caught. At some of the institutions, doors are left unlocked, security cameras are broken and officials sometimes don't notice an inmate is missing for hours.