Migration over the mid-Atlantic

Northwest winds across western NY and the mid-Atlantic triggered nocturnal migration into and out-of the region last night. Here’s the radar from 7:30pm last night through 5:00am this morning. Note that the Fort Dix radar is down for maintenance and so is missing from both the single and composite images.

Frames are every 1/2 hour. Click on the thumbnail to view the full-sized animation.

  Base Reflectivity image from Dover AFB Base Velocity image from Dover AFB Base Reflectivity image from Upton NY Base Velocity image from Upton NY Composite Base Reflectivity image from the Northeastern USA

So as Irene worked her way up into New England last night, high pressure built in behind her with strong northwesterly winds. Birds could be seen migrating over the Binghamton and Buffalo radars last night, heading in a strong NW->SE direction. When I checked the radar before bed last night, the Dover feed was looking great for a classic Cape May fall migration event. By that I mean migration was extensive (although not a ‘mega’ dense flight- definitely showing good density as well as being widespread) and showing a strong directional flow to the southeast. Because KDIX was offline, it was hard to tell how extensive the flight was coming from northern NJ, but given the similar winds I would guess it was pretty good. Watching the velocity image play through the morning hours, though, it becomes clearer that the winds subsided enough for birds to shift their trajectory to more N->S and disperse along the Delaware Bay shoreline by morning. This likely explains why the morning flight at the Higbee dike, while still good, was less than anticipated. Other potential explanations were that many migrants had been weakened/tired by the storm and probably did not eat much yesterday- probably opting to take another day at stopover habitat to refuel. A similar case could be made simply for the fact that less migration-ready birds were in the pipe to begin with- since many birds left the western NY area over the previous two nights- and so last night was really the third successive flight in the same number of days. Whatever the reason, we should expect a good flight of birds out of the New England area over the next few nights since no birds have really left there since the storm began working its way into the mid-Atlantic last week.

Right now it looks like high pressure will dominate into Wednesday, bringing about some decent migration conditions but without any strong northwest influence to push large numbers of birds to the coast where they’ll be more visible. Expect migration to be dispersed across the landscape over the next two nights. Shorebirds and landbirds are the most numerous migrants right now, but don’t forget the raptors which will be ramping up the diurnal action in the next days, weeks and months.

Good Birding

David

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One Response to Migration over the mid-Atlantic

  1. Corey Husic says:

    Decent morning in eastern PA. A few migrants, including Black-throated Green and Black-throated Blue Warblers as well as a migrant Cerulean Warbler! Bobolinks, Cedar Waxwings, and Purple Finches were moving after sunrise.