Posted by: woodcreeper | October 4, 2007 @ 6:29 am

Migration in the face of opposing winds


Winds were generally out of the E/SE last night, blowing around a low pressure system situated in the Gulf. That said, birds did appear to migrate, with the highest densities in the northern third of the state where winds pushed birds to the west.
Here’s the radar from sunset last night through 6:00am this morning.

Frames are every 1/2 hour for reflectivity and velocity, and every hour for the regional composite. Click on the thumbnail to view the full-sized animation.

Base Reflectivity image from Key West, FL Base Velocity image from Key West, FL
Base Reflectivity image from Miami, FL Base Velocity image from Miami, FL Composite base reflectivity for the Southeastern USA

The regional composite shows some movement across the state, although this is confounded by the “biotic soup” in the atmosphere (dust, pollen, insects, etc.). A closer look at the velocity still reveals some of this as birds migrating from NE to SW. No birds are seen leaving the southern peninsula, although a fair number are seen moving south across the Miami radar into the Everglades and upper Keys.

Good Birding! 🙂


  1. Most of the birds at both Matheson and Cape Florida seemed to have left Tuesday night, but a small number remained at Matheson this morning (10/4). Cape Mays, Redstarts, Parulas, and BTB’s are still present, but in smaller numbers than on Monday and Tuesday. No sign of either the Cerulean or Bay-breasted, but one of the two Magnolias is still around. Many fewer Ovenbirds as well. Thrushes and Orioles are missing, but there was a single Summer Tanager. Many of the raptors that were around during the early part of the week seemed to continue south following the warblers.

    We’ll see if the tropical wave that will move west by the weekend causes any kind of fallout. We are still desperately waiting for Octoberfest to happen.


  2. Banding today at Cape Florida bears out the observation of NE->SW migration. While it was slow yesterday, today it was almost in neutral. The 5:45-6:15 radar loop showed promise, including birds right off the coast. We observed flocks of Cattle Egrets and Great Blue Herons while banding, so this may explain the radar. Even with the great nighttime weather, a few birds just won’t leave. We recaptured a Veery with a 5.1-gram weight gain in 5 days and a recaptured Chestnut-sided Warbler banded 5 days ago was so fat that it almost couldn’t make it out of the tube. A Broad-winged Hawk shimmied out of the net, much to our relief. We’ll do Sharpies and Cooper’s but we leave the big boys to Maddog.


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