Do birds have a sense of smell, or is their beak just for breathing?

Question

Say they do have a sense of smell, how do they use it? Finding food, detecting preditors, identifying their young?

Answer 1

Most bird species have a very poor sense of smell.  However there are a few that depend on their smell to find food, therefore they have an excellent sense of smell. Some of these species are vultures and kiwis.

Answer 2

They do but it's pretty poor. Some song birds use their sense of smell to find their nest site after migration. However, the whole thing with "once a human has touched an egg/baby bird the parents will smell human and will turn their backs on it" is a myth - their sense of smell isn't good enough.