Tuesday, April 30, 2013

Local migration

The spring passerine migration is moving at a snail's pace here in Connecticut. As a co-worker of mine likes to say, "Aaaaand we're off like a herd of turtles!" As it should be in April in New England!

We've had a refreshingly cool spring with many nights of unfavorable migration conditions. So, for once, arrival dates are "normal" or perhaps even a bit behind in some cases. After last spring's record temps and insanely early foliage and birds (with foliage coming well before the birds), I am especially pleased by this year's developments. I know better than to think that this is an indication that climate change isn't occurring at a drastic pace, but it does make me rest a bit easier to see things much closer to normal as compared to this time last year, if only for a little while.

The most tangible silver lining here is that we're actually able to see warblers right now. Barring a prolonged major warmup, we won't have to fight through fully leafed-out trees for views of neotropical migrants when the first big waves arrive.

So when will that first wave hit? That all depends on, you guessed it...the weather. We are currently enjoying beautiful weather with many days of clear, sunny skies in the forecast. But the migrant flocks are few. Why?

Well, here in southern New England, we've experienced a slight easterly component to the winds over the past couple days. And a quick glance at the extended forecast currently predicts that easterly element to continue over much of the next ten days. Of course, this is subject to change at any moment. But when this happens, just a slight easterly component to the wind is usually enough to divert the bulk of migrants to our west. The birds keep migrating, but fewer end up in CT during these conditions. Breeding birds will continue to return, and migrants will still trickle through, but the migrants will be less numerous on east winds during May.

[*Note: This applies locally and to most east coastal locations. This is an over-simplification, as there are examples during which east winds can result in coastal fallouts of southern species (i.e. if they're ahead of an advancing low pressure system that pushes them offshore in the south but blows them back onshore further north), but those are special situations.]

So if the current forecast holds, we could be in store for a rather lackluster migration over the next week or longer in Connecticut. However, if you live a bit inland to our west, you should have no problem whatsoever. Enjoy our birds!

 - NB

2 comments:

  1. You jinxed us! The leaves are going to come out while we're waiting for the weather to change!

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  2. You're probably right Tom.

    The light winds are doing interesting things tonight. Maybe not so strong an easterly influence? Not holding my breath though.

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