Thanks for those article Deborah, very interesting indeed.
I didn't say they had no sense of smell by the way guys. And I do know that some birds like vultures have a strong sense of smell, I was referring to finches.

I have been known to use the hot pepper to keep squirrels out of the seed and the wild birds could care less.

I'm incline to think it may have more to do with the birds great eye sight and the light spectrum's that they can see that we don't even come close to being able to see, but that's just me.