During recap (short lectures and questions sessions usually centered around the day's activities) on one of the cruises I was on in December, someone asked how many feathers were on a penguin. I had no idea other than "lots." I knew that penguins had the highest feather density of all birds and were completely feathered without the feather tracts and apteria of other birds, but off the top of my head I had no idea what that density was nor how much surface area a penguin had.
I was doing some internet searches earlier today and thought I would look to see how many feathers were actually on a penguin. Turns out there wasn't anything I could find on Google or in my penguin books either. I did find some unreferenced numbers on feather density and some good numbers from research on the surface area of penguins from some heat loss/thermoregulation physiology studies. From those references I was able to determine that a Gentoo Penguin had a feathered surface area of 3288 square cm. and an Emperor Penguin has a surface area of 9000 square cm. I also found a number of references to feather densities ranging from 12 per square cm to 300! per square inch. I felt that the 12 per square cm figure was probably more accurate so I used that figure for both species and multiplied the numbers out to get approximately 36,700 feathers on a Gentoo Penguin and 108,000 feathers on an Emperor Penguin. I did find some information for the Little Blue Penguin that stated there were about 10,000 feathers on that species. That seems about right for the much smaller size of the Little Blue. My calculations may be a bit off since I am not sure where the feather density estimates came from on the penguin's body. There are many more smaller feathers on the head and flippers than on the torso of any penguin so I suspect my estimates may be a bit low but at least they are in the ballpark.