Here's why:
* Rookery: This term is used for a breeding colony of birds, especially seabirds like penguins.
* Breeding Ground: This refers to any location where animals gather to mate and raise their young.
* Colony: This is a general term for a group of animals living together.
While "rookery" is the most specific term, you could also use "breeding ground" or "colony" to describe where penguins and seals gather to breed.