Radar detects all kinds of weather: storms, snow, wind speed and direction. Every so often, it even picks up on large concentrations of living creatures, including birds, butterflies and mayflies.
These large masses of living creatures are detected by radar in the same way radar detects weather: the radar sends a beam out and it reflects back after intercepting precipitation and causing a reflectivity reading to be plotted. And in order for the radar to detect anything, there needs to be a lot of it.
According to AccuWeather Meteorologist Jesse Ferrell, detecting animals is similar to detecting raindrops.
"You need a large and dense enough patch of living creatures that the radar will reflect off of them, and they have to be high enough above the ground for the radar to see them," Ferrell said.
Meteorologists are able to tell whether masses are biological or not based on clues, including whether the mass of creatures appears in the same spot or whether the mass takes on a specific shape. Radar technology helps distinguish between "meteorological" targets, "biological" targets, and "non-biological" targets.
"There is probably some sort of flying creature swarm on one of NEXRAD radars at least once a week, except during the winter in cold areas," Ferrell said.
Here are some examples of biological targets showing up on radar: