Like many other observers, I've been surprised by the low visibility of
songbird migration this spring. I've hit a few waves of migrants over
the last couple weeks, but they've been clustered between long periods
of unfavorable weather. I wonder how many birds have simply flown over
us due to the small number of nights suitable for long-distance flight,
leading them to make fewer, longer, night flights. On several nights,
I've heard numbers of birds flying overhead, which weren't evident on
the ground the following day. Most of these night detections have been
Swainson's Thrushes and Veeries, but that's probably because their calls
are the only ones loud enough to hear over city noise. All of this makes
me think that birds are moving, but may be moving in distinct bursts and
possibly overflying us on their way to breeding areas.
That said, there are clearly many birds still to come through. I haven't
yet seen many female warblers, which tend to migrate after the males.
Flycatchers have been particularly scarce, especially empids other than
Least. A quick look at the migration counts on moumn.org confirmed that
the numbers of reports of most warbler species and many other migrants
are well below the levels for the same dates last year (though observer
effort could be contributing to that, or people may not have input their
sightings to the database yet).
This morning a Magnolia Warbler singing in my yard (in south
Minneapolis) drew me out to investigate what else might be around. Good
numbers of Tennessee Warblers singing, plus a Blackpoll and a
Blackburnian, several Swainson's Thrushes, a Veery, and a Gray-cheeked
Thrush. This is in a residential neighborhood with only a few large
trees, so I imagine other areas should have had plenty of birds as well.
Unfortunately I wasn't able to get to any good migrant spots before a
big thunderstorm hit, making the birding tough.
To sum up my perspective: birds are still moving, many have probably
passed by without detection, and decent numbers are probably still on
the way. My impression is that this is all mostly a function of stormy
and windy weather that is unsuitable for nocturnal migration. I'd be
curious to hear others' thoughts on this. I'll also be very curious if
the numbers of migrant reports eventually come up to last year's levels,
but later (indicating a late migration), or plateau at a lower total
number (indicating fewer or less visible migrants present).
Good birding,
Matt Dufort
Minneapolis
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