There are five endangered species of penguins I could have pick to write about for Penguin Awareness Day but I polled a number of students and they voted for the Erect-crested Penguin (is this surprising?). I have to admit this is a handsome bird and I'm not a huge fan of penguins. According to the IUCN, there are 60,000 - 70,000 breeding pairs. Sounds like a large number but the breeding locations are restricted to a few number of islands and a large oil spill or disease could decimate this species.
The Erect-crested Penguin is found in a small group of islands southeast of New Zealand. Their name literally translates as "the opposite side" as in the other side of the planet (from London I presume).
Populations were declining due to predation from introduced rats that presumably eat chicks and eggs. Amazingly and fortunately, rats were eliminated from the islands (Taylor 2000) so the population will likely increase. However, regardless of the absolute population size, this species has a restricted range, so it is likely to remain endangered.
One interesting tidbit I found in the literature was that the crested penguins lays two eggs and the first egg is smaller and often unviable or ignored by parents (Johnson et al., 1987).
Taylor, G. A. 2000. Action plan for seabird conservation in New Zealand. Department of Conservation, Wellington.
IUCN account http://www.iucnredlist.org/details/summary/22697789/0
Johnson, K., J. C. Bednarz and S. Zack, 1987. Crested penguins: why are first eggs smaller? Oikos 347-349.