---------- Forwarded message ----------
From: Dave Ziolkowski <>
Date: Wed, Sep 8, 2010 at 6:44 PM
Subject: Tune your ear, potential mass migration tonight!
To: Harford Bird List <>


Bill Evans, a preeminent migration/night flight-call researcher has
predicted that observers out tonight and tomorrow night are likely to
witness night flights of historical magnitude (his message is included
below). The moon is new so it will be too dark to train your scope on, but,
if you haven't done so before, now would be a great time to try out your ear
with night flight-calls.  Cuckoos and Thrushes are certain to be present in
numbers tonight, which is fortuitous since these are amongst the easiest
calls to recognize.  I have included links for both below (of the Thrushes,
note especially the Swainson's Thrush call, which bears a distinct likeness
to the song of the Spring Peeper).

***http://www.birds.cornell.edu/birdcalls/species/Cuckoos/
http://www.birds.cornell.edu/birdcalls/species/Thrushes/*
**
Good luck and good birding!

p.s. - As an aside, Venus and Jupiter, the brightest points of light in the
night sky, are briefly visible about an hour after sunset.  Venus is quite
low in the south-southwest, while slightly brighter Jupiter is in the east.

Cheers,

Dave
*
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Subject: intestine shrinker*
From: "Bill Evans" <wrevans AT clarityconnect.com>
Date: Wed, 8 Sep 2010 14:30:33 -0400

Greetings all,

We are in one of those situations in the northeast where connoisseurs of
nocturnal bird migration are in an especially heightened physiological state. I
know of no specific word for it, but it is when the anticipated flight is
looking so huge that it affects your adrenal function days in advance. In
tonight's case it is not simply the next cold front passage, but potentially a
movement of relatively large & perhaps historic proportions.

Here in deep interior northeastern US we haven't had a significant nocturnal
bird movement since the night of August 26-27. That's 12 nights without a major
flight. I looked back in my records of the last 20 years and there is no
similar event. The longest comparable string of nights around this time of year
without a significant nocturnal migration event is all the way
 back in 1992
when hurricane Andrew made landfall in Louisana and stalled out in the
mid-Atlantic states -- there was an associated period of about 10 days (Aug
20-30) of largely southerly winds across much of the northeast. A notable
dynamic that season was a temporal delay in the Veery flight while the
Swainson's Thrush flight came through right on time. This translated into a
record late high ratio of nearly 4-to-1 Veery to Swainson's Thrush flight calls
on the night of Sep 7-8, 1992 documented across a broad front at acoustic
stations near Watkins Glen, NY and another in Alfred, NY. Typically the bulk of
the Veery flight has passed south by then and the flight call ratio for these
species in central NY is 1-to-1 or lower. For example in fall 1991 at the same
two acoustic stations, the ratio was already down to 2-to-1 in the big flight
the night of Sep 4-5 that year.

The present delay in
 migration across the northeast is occurring later in the
season than the 1992 event, so the species effects will be different. I would
guess that half the Veerys are still north of central NY and that they will be
a regular caller across NY in tonights flight amidst the first substantial
numbers of Swainson's. I wouldn't be surprised if Veerys are more abundant than
Swainson's across upstate NY tonight and perhaps also in Thursday night's
flight. Certainly by the next cold front passage Swainson's will be the
dominant thrush call.

Going back to Dave Nicosia's recent posts, I agree that northeast winds are
relatively rare in the interior northeastern US. That wind direction would
seemingly be ideal for the dominant fall flight direction of passerines in the
interior northeast based on recent radar studies. Clearly these birds have to
traverse this region with less than ideal winds. Even a wind out of
 the north
would impart some crosswind on this southwest-bound movement. But the abundance
of SW winds we've had recently are direct headwinds for this flight. For a
species like Wilson's Warbler that wants to fly toward the southwest in fall
across the interior northeast, I speculate that their flight has been delayed
this year and that tonight (and perhaps even more so tomorrow night) may reveal
relatively large numbers of their flight calls. The graph below is historic
flight call data from Alfred, NY showing the proportion of Wilson's Warbler
flight calls in the mix of all warbler and sparrow calls (Tseep software flight
call detections).

Incidentally, the most Wilson's Warbler flight calls that were documented in
any of the nights noted in the graph above was 31 in nine hours of nocturnal
flight call monitoring on Sep 4-5, 1992 (post hurricane Andrew). That figure
considers calls within one
 minute of one another as a single call event and a
theoretical individual passing (there were 33 total WIWA calls that night). Ted
Floyd noted yesterday that he and his son heard WIWA flight calls at a rate of
80/hr a few nights ago in Lafayette, CO. Such a rate would be unprecedented in
the east, though the timing of the flight appears to be parallel. The good news
for the typically WIWA-starved folks in southern New Jersey is that if there
were ever a weather situation that would amplify your chances of recording WIWA
night flight calls, this is it and the next two nights should deliver.

In conclusion, I have to reiterate what Dave Nicosia said about the
uncertainties in predicting weather -- the same goes for bird migration.
Everything I know suggests to me that tonight (and tomorrow night) look to be
huge nocturnal flights across northeastern US. The spring is set as tight as
for any early
 September night I've seen in the past 20 years. Theoretically
there is an uncommonly large number of birds ready to fly, and we are in the
time when peak numbers of neotropical migrants typically move across the
region. Given that the numbers of night migrants in eastern North America are
undoubtedly getting smaller annually due to increasing numbers of man-made
fatality sources (windows, towers, etc) and habitat loss, this may well be the
largest early September nocturnal migration event we have the opportunity to
experience in the remainder of our lives. If you live in northeastern US or
thereabouts, you might want to consider taking the next few nights and days
off.

Turn on, tune in, bird out,

Bill E

p.s. for those within 100 miles south of Lake Ontario (e.g., Ithaca and west),
it is likely that the numbers of birds ready to fly south of the Lake have
leaked southbound over the past
 week and a half. We may have to wait for the
wave of birds crossing the Lake (e.g., after 11PM for Ithaca area) to
experience any kind of substantial migration magnitude via auditory or other.