that's odd, I have always read and observed in the field that birds in general have very very poor sense of smell, virtually non existent in most, especially vultures as they feed more on sight than smell. The exception to that is the turkey vulture, they actually have a very good sense of smell, yet their is still a lot od debate on just how well they can smell a carcass at 5000 feet, those odors just dont go that high, so they still are basically feeding off sight til they get lower.
That and other than say vultures, their sense of smell has no real bearing on their day to day life, search for food, etc. Now their eye sight cant be beat and are pretty darn good at hearing as well, as you mentioned.
I know my human odor has never been smelled by a bird in the woods. I am a hard core hunter, been busted by virtually every animal in the woods threw smell at one point in time or the other, but never a bird. They use a different part of the brain, true, but is it effective?
I have had friends who are waterfowl and turkey hunters go with me and sit just a few feet from the birds smoking cigarettes and never be noticed.
This is curious to me is all, because it goes against all I have read and witnessed first hand on them (birds in general that is)
Now I know from species to species there will be variations in all this, and have seen recent studies based on prehistoric fossils and their olfactory section of the skull being much larger than say todays birds. Back then as they were developing, I thought eye sight and hearing developments kinda pushed back the need for excellent olfactory systems, thus over time, their eye sight got better, but smell weakened considerably, kind of like us when we loose our eye sight, or hearing gets better.
There are a few species I have read up on that do sport a decent olfactory system, but most are pretty primative, and little more than just two holes in the beak.bill at this point.
do they smell, yes, but barely ducks that is. Would like to see some studies showing otherwise. Currently, all I have found is yes, like all animals they can smell, but outside of just a few it is a very poor sensory development. Those with good systems, actually are only keyed in on things (food) that they need in their day to day life.