Ross

Many thanks for the clarification.  The Birdscope article says nothing about 
the "year after."

Jim

-----Original Message----- 
From: Ross Geredien
Sent: Friday, May 20, 2011 11:03 AM
To: 
Subject: [MDOSPREY] 17-Year Cicadas and Bird Populations

Jim and others:
Just to be clear, the study by Koenig and Liebhold does conclude that most 
of the species examined experienced significant population increases during 
the year after the 17-year Cicada irruption.  This conclusion makes sense, 
since the benefit of high food abundance would result in high brood numbers 
and overall reproductive success, which would be detected in subsequent 
years.
But the question of cicada cycles being timed with those of avian 
populations is an interesting one, and worth further exploration.  Thanks 
for sharing, Jim.
For those who are interested, the original article was published back in the 
July 2005 issue of Ecology.  The full citation is:
Koenig, Walter D., and Andrew M. Liebhold. 2005. EFFECTS OF PERIODICAL 
CICADA EMERGENCES ON ABUNDANCE AND SYNCHRONY OF AVIAN POPULATIONS. Ecology 
86:1873–1882. [doi:10.1890/04-1175]
Ross GeredienEdgewater, MD

--- On Fri, 5/20/11, Jim Wilson <> wrote:

From: Jim Wilson <>
Subject: Re: [MDOSPREY] 13-year Cicada update
To: 
Date: Friday, May 20, 2011, 10:32 AM

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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