Thursday morning’s radar image on Storm Team 27 VIPIR Radar was interesting. It showed a ring develop over parts of Portage County.

Why was there a ring on the radar?

The doughnut-shaped ring that showed up on the radar was caused by birds. This happens when the radar beam detects a large number of birds, more than likely 1000s, as it scans across the sky.

The birds that were caught Thursday morning were most likely Purple martins. They were taking off from their roosting site near the Portage Lakes area in Northeast Ohio. They were likely heading out for breakfast.

These rings on the radar are known as “Roost Rings” and are made by the birds taking off in all directions and climbing in height as they leave the roosting site.

As they move out away from the site and climb higher in the sky, they push higher than the radar beam causing the return to not be as intense. This is why it appears that they fade away. They are not fading away, though, they are climbing higher/lower than the radar beam. This can also happen as they fall below the radar beam.

They also return to the roosting area at night, but the atmosphere is typically not the same. The temperature inversion during the morning helps bend the radar beam, which helps in the detection of catching this interesting radar loop. At night, this does not happen as often.

Why is the Purple martin in Ohio?

The martins are gathering this time of the year in large colonies in order to rest up for their migration south. They start their migration south during late August and early September.

Purple martins stop by this location to rest up for their journey back to South America.