An exodus of birds occurred last night, as some modest precipitation moved in from the south. The precipitation eventually catches up with the migration and shuts it down. Interpretation is difficult, since I’d expect little influx due to the origin of precipitation, although most of the radars to our south showed a similar level of migration before the rain became heavy (so I may be underestimating any influx). There could be localized concentrations of birds that were already in New Jersey (or nearby, to the south) as of last night, but were put down by the overnight rain. Where to find them? Your guess is as good as mine.
The radar loop is from sunset last night until sunrise this morning; images taken hourly.

I’m posting the full reflectivity and velocity loops for any radar geeks out there (me included). These files are big (>1MB), which is why I initially posted the 1-frame/hr loop above. These loops are 4-frames/hr and run from sunset last night until 1 hour after sunrise this morning. What I see is, again, a big movement over New Jersey after sunset which is overtaken by precipitation after about 2am, but continues until around 3am. I have extended the time of the three frames following the end of the migration event for easy recognition. You’ll recognize them on the velocity image as the ones where the “red” pixels disappear. The red pixels represent birds flying at speeds >20kts faster that the prevailing winds. I have also slowed down the radar loop during those same three frames, and you can see that the weather system was already overhead for about an hour before ceasing the migration event.