The idea of "migration corridors" is a misnomer. It would be so much easier
if true but unfortunately it does not appear so. There is a perception
(probably true at least in some cases) that major north-south river
corridors have a greater concentration of migrants than random chance. But,
for most species migration occurs on a broad front. This is different by
species, season, and often by sex and age.
There is strong evidence that migration does "funnel" into major stopover
habitats such as the Lake Erie Marshes. But, there are questions to be
answered there as well. How far away does funneling begin; is it more
related to remaining habitat and lake effect just to mention a couple.
Evidence does indicate "migration routes" by species are and can be
influenced by both biological (age/sex) and environmental (weather) factors.
Some diurnal migrants (raptors) do exhibit some relationship to wooded
corridors such as rivers which provide stronger thermals than the
surrounding agricultural environment. Was this true 300 years ago?
Waterfowl and shorebirds are known for high migration passage unrelated to
local habitat below. Their guidance comes through other means with a
destination programmed in. Songbirds migrate from diverse starting points,
often in loose flocks to wintering areas that are also diverse in location,
primarily at night when land features are minimal in guidance value.
There is not one magic answer or map. So many of today's threats to our
birds want these simple maps, but sadly it just isn't that simple. There is
so much more we need to understand to provide the protection and
conservation of the avian world that we are rapidly altering.
Mark Shieldcastle
Research Director
Black Swamp Bird Observatory
13551 W SR 2
Oak Harbor, Ohio 43449
419-898-4070
www.bsbobird.org
www.ohioyoungbirders.org
www.biggestweekinamericanbirding.com
Become a fan of BSBO & Ohio Young Birders Club on facebook at:
www.facebook.com/bsbobird
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-----Original Message-----
From: Ohio birds [mailto:[log in to unmask]] On Behalf Of
Hutson, Timothy B
Sent: Monday, October 24, 2011 12:42 PM
To: [log in to unmask]
Subject: [Ohio-birds] major Ohio migration routes
Just wondering if there are any resources out there that identify major
migration routes throughout Ohio. I'm curious to see if the routes taken by
the various species are known and documented. I would assume that
shore/water birds have favored routes (perhaps along river corridors) but
that temperate migrants may just flood south in the fall. I just don't
know.
Thanks
Tim
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