Below are a series of interactive maps from Achievement Hunters
for all the feathers/glyphs/statuettes in each of the regions:http://achievementhunter.com/games/guides/ac2/
If you find you have missed any feathers, you can narrow down the search by pressing Start whilst in the game and selecting DNA. Follow the DNA strand along until you reach feathers.
It will show total number collected out of the maximum 100. Press X and it will then break it down by the cities. Press X again on the city of choice and it will then show you how many you have collected in each region of that city.