For the second night in a row, southerly winds on the eve of the approaching cold front have kept precluded any appreciable movement of birds. Here’s the radar from sunset last night through 5:00am this morning. Note, though, that some frames are missing due to radar error.

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

It’s always good to know what “no migration” looks like on the radar, just so you have a benchmark to which you can compare an actual flight. Looking at the NY and NJ radars, it’s apparent that something was in the air after sunset, but the reflectivity was 1) not nearly as strong as on a night with migration, and 2) the signal was ‘short lived’, in that it only appeared for a few hours, then rapidly disappeared.

Looking at the velocity we can immediately rule out migrating birds. All targets moving across the radar appeared to be moving with the wind, from south to north- not the general direction of fall migrants. Since the target velocities were quite high, the general impression might be that of migration. This is because we’re used to seeing birds migrate at velocities of 20-30+ kts (although usually the wind speed is only between 5 and 10 kts, and therefore birds are moving 15-20 kts faster than the wind). The wind speed last night was closer to 20 kts, and consistent with the velocity values depicted on the radar.

So given the lack of migration last night, we have a backing-up of migration-ready birds upstream of us. Looking at the regional composite you can see how this is going to play out tonight. Check out the frontal boundary that made its way east across the Great Lakes. You can see birds taking off almost immediately after the front passes. Well, that should be us over the next three nights! Expect heavy migration tonight and tomorrow night, with continued movements on Friday night as well… it’s about to get really birdy around here…

Good Birding

David