National Overview
The National Composite really tells the whole story this morning, so I’ll keep it brief. The low pressure systems which affected the central U.S. over the last few days have now pushed to the east coast bringing with them strong northeasterly surface winds and a mix of precipitation severity. Overall winds across most of the Eastern U.S. have turned less favorable for migration which is reflected in the virtual absence of migration signal on the radar last night. The big exception, of course, is Texas through the Great Plains region where a tight band of southerly winds and clear skies resulted in another night of birds heading north.
Below are the radar loops from sunset last night through 5:00am this morning
New Jersey (Mid-Atlantic)
Frames are every 1/2 hour. Click on the thumbnail to view the full-sized animation.
Nothing to show on the Dover, DE and Fort Dix, NJ radars last night, and that goes pretty much for the entire Mid-Atlantic region. Precipitation could be seen moving SW->NE across the region, but surface winds were stiff and out of the NE last night (which can also be seen on the radial velocity loops above). There was no evidence of reverse migration on the radar, but see below for an interesting look from the Upper Midwest. Birding conditions should remain similar to yesterday with some localized movement into more optimal foraging habitat. Find the spot with the early bud burst (and hence the attraction of early-hatched insect larvae) and you should find the birds hammering this unseasonably available food source.
Wisconsin (Upper Midwest)
Frames are every 1/2 hour. Click on the thumbnail to view the full-sized animation.
The Upper Midwest, as well, was very quiet last night. Comparing the reflectivity and velocity for each of the Wisconsin radars last night I would rule out most of the signal presented here as ‘noise’, or aerial plankton (a mix of pollen, some insects, and a very few birds/bats/etc.). La Crosse shows a small SE->NW signal which I suspect represents the few birds/bats/etc. but for the most part what we see reflected in the radar is heading either N->S at or near wind speed, or shows no heading at all (typical of anomalous propagation). Milwaukee is a little more interesting because there is a clear southbound migration event early in the night. You can see it coming from the lakeshore side, northeast of the radar, and heading south along the east side of the radar where it continues out of the radar view. There is also a more general and diffuse movement from N->S that I also suspect are some birds engaging in reverse migration- but this tight little cell makes me wonder if we’re not seeing waterfowl movement off of the lake. I don’t see any evidence that this group of birds moved back north during the night, which might be indicative of a nightly foraging event, but with data this coarse and only looking at a portion of the night, it’s hard to say for sure. Either way it’s interesting to see reverse migration on the radar and it’s not surprising considering the superhighway of northbound birds over the past two weeks. If nothing else, it’s important to think about how dynamic this migration behavior can be, and to consider that even with record early arrivals of some individuals, there may be a hard-wired response of some birds to backtrack when signals on the ground indicate they may have gone too far too soon.
Of course all of this is speculation without ground-truthing, so be sure to come back and let us know what you saw. The best way to do that is by sharing your eBird checklist from today in the comments section below, as well as any notes and observations you may have made.
Good Birding,
David