Bill,
I have noticed this quite a bit lately too. Birds moving no matter what the
wind direction is.
Looking at base velocities I did notice very weak velocities on a couple
occasions with
the predominant direction close to the actual wind direction. This could
suggest
birds were not favoring a particular direction or were wandering with the
winds.
Winds were light in these two instances.
However, if we do get more northerly winds, wouldn't the movements increase
even this
early? If not, does this suggest a lot of birds just wandering around, post
breeding dispersal etc?
Since it is still summer and there is plenty of insect life around, why would
most insectivorous species
have to be in such a rush to fly south? And if they were in such a rush, they
certainly
would take advantage of favorable northerly winds, at least you would think
they would.
This is all pure speculation.
I have seen big pushes after fronts in September and October like you state.
Since insect life and light is
declining fast by this time, this makes more sense since the birds are running
out of time and want to get
south as fast as possible.
So maybe we are witnessing a lot of birds wandering around this early that are
not as serious
about getting to the tropics? I know some species migrate to the tropics very
early so this does
not universally apply. It will be interesting nevertheless to see if this first
front increases
the bird echoes or not. These are all mysteries I guess...which makes the whole
migration thing so
fascinating. I will also look at the lighter echo nights more closely and
compare base velocity signatures
with actual wind data to see if we are witnessing wandering or a true southerly
component or
a component along the wind. Thanks Bill, you have sparked some ideas for me...
Best,
Dave Nicosia
From: Bill Evans
To: david nicosia ; NFC- L
Sent: Saturday, August 4, 2012 9:00 AM
Subject: Re: [nfc-l] First Big Southbound push of fall migrants next few days
in northern U.S??
I’ve noticed via flight call monitoring at this time of year (in NY and
vicinity) that songbirds tend to move every night regardless of cold fronts --
unless there are strong southerly winds or substantial rain events. Later in
the
season (mid-September – October) the flights seem more tied to coldfront
passage. I have a transect of acoustic monitoring stations across NY this fall,
repeating my 1992 VCR effort. As with the Alfred, NY acoustic station last
fall,
I’m putting the previous night’s warbler and sparrow flight call tallies and
tentative species IDs online in the morning at http://www.oldbird.org. By
browsing the data
you can see that substantial nocturnal migration has been underway in NY over
the past three weeks, and there are already interesting species patterns
apparent. For example, while Black-and-white Warbler flight calls are just
beginning to be detected across eastern NY in the past week, a small but steady
pulse of Black-and-white Warbler night flight calling has been occurring over
south Texas for the past three weeks. Btw, for anyone interested, the whole
audio archive from the Old Bird acoustic stations this season will be available
early next year on a ~5 TB external drive. This will have the raw audio
files, extracted flight calls, and contributed analyses. Anyone out there
recording with the 21c or comparable mic in a relatively clean acoustic
environment is welcome to merge their work into this evolving public archive.
Many lifetimes needed to get a handle on all this!
Bill E
From: david nicosia
Sent: Friday, August 03, 2012 6:25 PM
To: NFC-
L
Subject: [nfc-l] First Big Southbound push of fall migrants next few
days in northern U.S??
All,
I have noticed every night that the radar bird echoes are picking up more
and more
even when the winds are not that favorable.
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