The Spring 2011 Cornell Birdscope Newsletter has an interesting short piece 
about birds and the 17 year cicadas.  The info is very counterintuitive.  I 
quote:

    "  Koening's research team found, using data from the Breeding bird 
Survey and Christmas Bird Count, that many insectivorous birds declined in 
numbers during the 1987 and 2004 emergences of the "Great Eastern Brood," 
another population with a 17 year cycle.  Of the 24 species they 
investigated, they found that only 2 species, the Yellow-billed Cuckoo and 
Black-billed Cuckoos, increased during cicada emergences, while 16 
decreased.

    ... It looks like the cicadas are somehow engineering the bird 
population by their cyclic life-history to be less common when emergences 
take place, reducing predation pressure.  The mechanism behind this is 
obscure, but the fact remains that this provides a glimmer of an ecological 
explanation for why there might be 13 and 17 year cycles."

Jim Wilson
Queenstown 

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