I've just started getting eggs from my birds and can't tell if some of them are duck or chicken eggs. My ducks are only 6-7 months old, but some of my eggs are rather big. I have 5 that are the size of XL chicken eggs, 4 white and 1 green. The duck breeds are Rowans (sp?) and Buffs. My chicken breeds are: Buff Opington, Black Austrolorp, Easter Eggers, Barred Rock, Rhode Island Red, and Light Brahma. I've been also getting 3 different shades of brown eggs, one is almost a redish color. Chickens are less than a year old.