A Pigeon Atavism: An Innate Fear-Response To Snake-Like Things?
[T]he window of my office at the New Zealand university where I teach is high, and its ledge offers a convenient perch and nesting place for pigeons. Whatever their charms, these creatures, alas, are extremely messy; they finally made the ledge so unhygienic that the window had to be kept shut at all times. How to keep them away? My solution is a rubber snake on the ledge. I have seen the birds land on the ledge, see the snake, and immediately depart. They don't come back. The odd fact is that, although European pigeons have been in New Zealand for a couple of hundred pigeon generations, there are no snakes in New Zealand and never have been. The phobic reaction of the birds is therefore learned neither from exposure to snakes nor from images of snakes. In snake-free New Zealand it is a perfect instance of a natural atavism: an innate fear-response that is passed, unnecessarily in these parts, from generation to generation of pigeons.
-- Denis Dutton
from "The Art Instinct: Beauty, Pleasure, and Human Evolution"
Quoted on Thu Aug 4th, 2011