The greatest mystery about bird migration is the ability of many birds to move over the same route, year after year, arriving each spring in the same nesting locality and spending each winter in the same place."
(The greatest mystery about bird migration; is; the ability of many birds to move over the same route, year after year, arriving each spring in the same nesting locality and spending each winter in the same place)
The greatest mystery about bird migration
is
the ability of many birds to move over the same route, year after year, arriving each spring in the same nesting locality and spending each winter in the same place