Mammals living on the Crozet Islands include fur seals, and southern elephant seals. Killer whales have been observed preying upon the seals. The transient killer whales of the Crozet Islands are famous for intentionally beaching (and later un-stranding) themselves while actively hunting the islands' breeding seal population. This is a very rare behaviour, most often seen in the Patagonia region of Argentina, and is thought to be a learned skill passed down through generations of individual orca families. These killer whales also seem to stay around the Crozet Islands year-round, feeding on mostly seals during the summer, and then feeding on penguins for the winter.