So Pete Dunne came into my office the late last week and asked me whether I could see the Mauricetown swallow roost on the radar. He monitors this location regularly, and often speaks of the spectacle of tens of thousands of birds taking to the air after sunrise. I knew I had seen roosts before on radar- but hadn’t looked for this one specifically, so I dug through the last few mornings of radar images to see what I could come up with. Low and behold, the roost was VERY active on the radar, and not only that- there appear to be several others nearby! Here’s a loop from August 19th:

I have labeled the roost with a red arrow, and added two other red arrows for separate areas that appear to be roosts as well (Mauricetown is the farthest east of the three). I’m not sure of the species composition at the other two sites, but the signature looks good for a swallow roost. Alternatively, it could be a heronry, as I’ve seen similar signals from such down in Florida. If you have any first-hand evidence of the species present at either site, please add a comment to this post. You’ll also notice a yellow arrow that pops up around 6:30am, pointing out an eastward strobe. This is caused by sunrise, when the sun breaks the horizon and “hits” the radar directly. You’ll see this on radar at both sunrise and sunset, and I find it fascinating to watch how quickly the birds take to the sky in nocturnal migration after seeing the westward strobe flash across the radar screen.

Below are two more animations, without the arrows, from August 22nd and 23rd. Thanks to Joe Pylka for bringing the WHYY article to my attention, via Jerseybirds. These animated loops span 6:00 to 6:30am.