Why do penguins only live in the south polar region and not the north?
(Lansing State Journal, July 21, 1993)
Why haven't penguins colonized further north? While no single explanation can be given for penguins’ limited range, a variety of natural mechanisms surely act to contain wild penguins near the Antarctic Circle.
The range of an organism is the geographical area within which it can be found. Natural boundaries of species causes, all of ;which affect resource availability. Some of these causes are the behavior of the species in question, range overlap with potential competitors and predators, and geographical barriers. In this case, all three can be shown to affect the range of penguins.
First of all, penguins are shore birds. While they have the capacity to swim great distances, they usually do not venture far from the beach. The presence of other animals, including prey and predators of penguins, also encourages the flightless birds to stay close to home. In addition, the transition to warmer waters probably discourages migration across the tropics.
Lastly, one should recognize that the geographical origin of all penguin species is near to their present range. Though not all species of penguin have survived, as a family of birds their range does not seem to have changed much in the last 40 million years.