One examle is the kakapo, a New Zealand parrot that is unable to fly.  The birds have also grown into some of the largest birds ever, thanks to lack of significant predators such as rats or cats.  The moa can grow to be more than seven feet tall, but unfortunately were hunted into extinction a few hundred years ago.  These days, native birds including the black robin and the takahe and kea are protected to ensure their survival for the years to come.