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CarolinaBirds for Friday, August 11, 2006
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Subject: Current issue of Science
From: Carol Williamson <cncbrdr(AT)yahoo.com>
Date: 11 Aug 2006 11:16am
Some of you may be interested in seeing the current
issue of Science, particularly with regard to bird
migration.
Science 11 August 2006:
Vol. 313. no. 5788, p. 775
DOI: 10.1126/science.313.5788.775
Prev | Table of Contents | Next
Introduction to special issue
"When to Go, Where to Stop"
Andrew Sugden and Elizabeth Pennisi
The ability to move, at some stage in the life cycle,
is fundamental to success in life. Passive drift in
water columns conferred a selective advantage for
early life, offering an escape from starvation and
genetic uniformity. Since then, organisms have evolved
many ways to disperse and migrate in response to the
pressures of finding resources, escaping predators,
seeking out mates and suitable breeding grounds, and
distancing themselves from family. Dispersal in its
broadest sense means movement away from the
birthplace. Strictly speaking, migration involves
travel in a periodically and geographically
predictable way, whether it occurs just once or many
times. In this issue, Science deals with what we know,
what we need to know, and how we are going to find out
more about both of these movement types.
In plants, the spore, seed, or fruit is typically the
unit of dispersal. Although the many morphological
adaptations for their dispersal are known, until now,
researchers have been unable to determine the
distances traveled or the proportion of dispersal
events that lead to seedlings. In one Perspective (p.
786), Nathan describes recent developments in the
modeling and measurement of the long-distance
dispersal of plants. A News story by Holden (p. 779)
discusses the push to come up with a theoretical
framework, not just for plants, but for all moving
organisms. Organisms also disperse in reaction to
changing habitats and climate. The Perspective by
Kokko and López-Sepulcre (p. 789) discusses the
selective forces affecting this ability in animals and
how dispersal translates into range expansions and
contractions. Kintisch (p. 776) describes the
challenges for marine scientists assessing how climate
change may affect oceangoing species.
Humans have been great dispersers. Colonizing new
habitat has been a hallmark of human ecology over the
past million years or so. In a Review (p. 796),
Mellars considers recent advances in archaeology and
genetics that are illuminating the controversies over
the routes taken by ancient peoples in the
colonization of Asia 40,000 to 60,000 years ago. Two
Perspectives consider migration: Holland et al. (p.
794) focus on migrating insects, which tend to travel
in established geographical patterns across several
generations rather than returning to their birthplace,
and Alerstam (p. 791) discusses the accumulating and
sometimes conflicting evidence about the navigational
mechanisms used by animals (particularly birds) in
long-distance annual migrations. In a related Report
(p. 837), Muheim et al. describe the role of polarized
light at dawn and sunset in calibrating the magnetic
compasses of migrating birds. A News story by Morell
(p. 783) describes a new model that will clarify the
mix of genes and environmental responses underlying
successful bird migration.
As News stories by Blackburn and Holden (p. 780) and
Unger (p. 784) point out, ingenuity and persistence
are beginning to pay off in new techniques for
following organisms, be they fish, crabs, jellyfish,
rhinos, or polar bears. Thanks to these advances, the
study of the ecology and evolution of movement is
charging ahead and unearthing the challenges faced by
organisms in dispersing and migrating in a world
undergoing anthropogenic change.
Carol Williamson
Durham, NC
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Subject: Migrant Yellow Warbler in central Halifax County
From: "Frank Enders" <fkenders(AT)hotmail.com>
Date: 11 Aug 2006 6:11pm
This morning I heard and then saw (naked eye view) a Yellow Warbler,
probably an immature, in the willows at my pond near Darlington, central
Halifax County.
I see in Virginiabirds that several have moved south in that state, as well
as a few other warbler species (N. Waterthrush and some other, in
ALexandria).
Frank Enders, Halifax, NC
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Subject: Four anhingas remain near Enfield
From: "Frank Enders" <fkenders(AT)hotmail.com>
Date: 11 Aug 2006 6:09pm
About 0.3 miles west of I-95 on south side of NC481, the Great Blues have
gone, but one nestful of 3 plus a spare Anhinga farther west were present in
the tupelo grove on 10 August, 2006.
Anhingas have been seen flying around the area by an electrician in Rocky
Mount, as well, in the last few days.
The young birds will probably leave the nest within the week. LAST CALL.
Frank Enders, Halifax, NC
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Subject: Catbird on the move in Halifax County
From: "Frank Enders" <fkenders(AT)hotmail.com>
Date: 11 Aug 2006 6:20pm
This morning as I was trying to kill some Bidens (Spanish needles) I heard a
catbird mewing at me in the thicket near my home.
Does not breed within a half mile (or maybe for two miles). Clearly this
catbird is a migrant.
Last week or so, I had failed to describe perhaps the best bird we found at
the Stamper Siding Road sod farm in Scotland Neck: a Catbird SINGING from
the power line at the road. In back of it was a corn field. The nearest
woods (or woody vegetation) were 200 feet from the singer. THe bird just
moved to a higher wire when we got out of the car to view shorebirds.
In retrospect, perhaps this Scotland Neck catbird was also on the move away
from the usual breeding sites.
Frank Enders, Halifax, NC
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Subject: Brown-headed Nuthatch on the move last week
From: "Frank Enders" <fkenders(AT)hotmail.com>
Date: 11 Aug 2006 6:14pm
About a week ago I had a Brown-headed Nuthatch making some long (200'?)
flights to and from the powerlines on my farm.
We last had this species nesting maybe 15 years ago in an old fence post.
Most of the pines near that were logged out, and the species has not been
present since.
I assume this bird is seeking a home. The nearest nesting area is probably
about 4 miles east of here.
Frank Enders, Halifax, NC
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Subject: Migration
From: Tim <trlewis(AT)indylink.org>
Date: 11 Aug 2006 7:34pm
A flock of about a dozen Black Vultures were roosting during the rain
this morning in Dillsboro. They are not common at this elevation so they
may be "snow birds" from the larger population in the Tennessee Valley.
We are still hearing and seeing our summer resident Red-eyed Vireos and
Hooded Warblers daily plus occasionally a Blue Headed Vireo, and Scarlet
Tanagers.
I put up a second hummingbird feeder on the other side of the house
thinking that maybe they would prefer to switch than fight. Not true. We
have up to 5 at a time on one feeder then change sides and fight again.
Tim Lewis & Lori Unruh
Dillsboro, NC (Jackson County)
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Subject: "flock" of Bachman's Sparrow
From: "John Fussell" <jfuss(AT)clis.com>
Date: 11 Aug 2006 8:31pm
Allen Bryan and I had the interesting experience of being in the middle
of a group of at least 8 Bachman's Sparrows on Wednesday, in the south
Croatan National Forest.
There were definitely immatures in the group, but can't say there were 6
of them, which, based on what I've read, would be quite a large clutch.
John Fussell
Morehead City, NC
jfuss(AT)clis.com
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