Killdeer (Charadrius vociferus)

I went out to Albert Head Lagoon a little while ago to see what kinds of birds were there - it's bird sanctuary. However, aside from a few distant ducks and swans the only birds I saw were some Killdeer (Charadrius vociferus). I've posted photos of Killdeer before and mentioned the deception they practice when their nests or chicks are threatened. I've learned recently that this behavior is not unique to Killdeer but is shared by some other ground-nesting birds. How such behavior developed is not known. Here is what it says in my "Birder's Handbook" (Ehrlich, Dobkin and Wheye 1988, Page 115):

There is little doubt that effectively leading a predator away would be strongly favored by natural selection but how these stylized antics evolved remains controversial among behaviorists. Some conclude that distraction displays are a product of the conflicting desires of the parent to approach the predator aggressively, to return to the nest, and to retreat. Others suggest that they evolved directly as a predator defense, with more stylized sequences found in species that have had longer association with heavy predation.

The more I find out about birds the more I realize how much more there is to learn and how much yet remains to be discovered.