Methyl anthranilate [0], commonly used as artificial grape flavoring and naturally found in Concord grapes, is a bird repellent. They can certainly smell it, if not other odors.

If you want to keep birds out of your strawberry patch, for instance, you can sprinkle packets of grape Kool-Aid over it.

[0] https://en.wikipedia.org/wiki/Methyl_anthranilate