Just out of curiosity, what deep seated biological / mammalian fear does a bird tap into? Snakes, spiders, insects, etc. I get. Birds?
I worked with a woman with a bird phobia. Sadly for her, we often left the office door open on nice days, and birds flew in -- right over her desk -- on several occasions.
Her phobia originated in early childhood and was related to having been chased by newly-headless chickens.