Posted by: woodcreeper | September 19, 2008 @ 5:57 am

Heavy migration into North Florida; slower to the south

The winds over Florida were ENE last night, so the lack of major migration in the southern half of the state likely reflects an exhausted pool of migration-ready birds. Here’s the radar from 7:00pm last night through 5:00am this morning.

Frames are every 1/2 hour. 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

Actually, the reality of last night’s migration appears far more complicated than I made it sound above. Okay, let me try and sort this out…
If you look at the composite image, you can see strong signals across North Florida, the Panhandle, and the southeastern US, suggesting a very heavy influx of birds into the state. Look specifically at the Jacksonville radar, as well as the radars over Charleston, SC and Georgia. Between midnight at 4am these radars go almost totally green… and each of them shows strong NE->SW flow at speeds consistent with migrating birds… if these are all birds, it represents the densest concentration of migrants I can remember ever seeing on the radar from any one location.

As you move down the state, though, migration activity decreases precipitously. Birds are on the move across the entire state, but only at low to moderate densities despite optimal conditions. This is quite common after a few good nights of migration, where the pool of available migration-ready birds has been depleted. Hopefully the folks out at Cape Florida can give us an idea of their recapture rate today, which would indicate what proportion of birds are sticking around vs. being replaced by new ones (although a few banding stations worth of data would be helpful in this regard). Birding conditions in the upper Keys should be good today, as the birds which did move over Miami last night appeared to be heading due south with little sign of movement beyond the island chain. Otherwise conditions in the central and southern part of the state should remain similar to yesterday. North Florida and Panhandle birders should be on the lookout for high densities of new birds dispersed across tried-and-true fall migrant traps, with the east winds favoring slightly inland or west coast locations.

Good Birding,


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  1. Hey David
    Your post seems to be on point, this morning we birded several areas around FIU with no new birds. We saw the same species and numbers as we did yesterday morning on campus. Still we can’t complain about having migrants down here! We saw the following migrants on campus.

    Turkey Vulture (heading due south)
    Red-Eyed Vireo
    BG Gnatcatcher
    Prairie Warbler
    Black-throated Warbler
    A. Redstart

    No big numbers but some representatives of each were around.

    Nature is awesome,
    Angel & Mariel

  2. Is “on point” the same as dead-on balls accurate? Your assessment of migrants arriving in Cape Florida seems spot-on. Nice job! A quiet morning with no flight calls (Bobolinks flew over in a short span from 7:30-9 AM). We banded 38 new of 11 species. The health of these birds was a real mixed bag, with some of them in pretty bad shape. Recaptures were from several days ago, again, still not in great shape. A glob of Ovenbirds showed up late morning, most in poor shape. Whoever is at the Cape now needs to eat! The bright spot today was banding a handsome HY male Baltimore Oriole.

  3. The C-111E Canal area still had a lot of bird activity this morning, mostly the same bird species that have been seen in the past couple of days but perhaps with fewer numbers and variety:

    Northern Harrier (1)
    Belted Kingfisher (1)
    Eastern Kingbird (8)
    Gray Kingbird (1)
    Great Crested Flycatcher (2)
    Alder Flycatcher (1, calling)
    Red-eyed Vireo (3)
    Yellow-throated Vireo (heard only)
    Blue-gray Gnatcatcher (8)
    Northern Parula (1)
    Prairie Warbler (9)
    Black-throated Blue Warbler (2)
    American Redstart (8)
    Hooded Warbler (1)
    Ovenbird (3)
    Common Yellowthroat (7)
    Baltimore Oriole (5)
    Orchard Oriole (1)
    Blue Grosbeak (5)


  4. This in an email from Laura Johannsen:

    Just to confirm your suspicions for Fri/Sat/Sun, I did see large numbers of mostly Palm, Prairie, and Common yellowthroat warblers. I live on the north side of Jax on a golf course that closed almost 2 years ago. As I walk many of the old fairways, now filled with mostly dog fennel, the warblers come pouring out. A single fairway can hold nearly 300+ birds hidden in the vegetation. It was the same last year. It has been quite a site! Yellow warblers, Redstarts, and Summer tanagers were in the mix. I may not have huge species count (40 on Sat NAMC), but the numbers are something.

    Laura M. Johannsen, MT (ASCP) M. Ed.


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