Click here for an animated map of the United States showing today’s migration movements.
The term “NEXRAD” stands for next generation radar and is used by avid birders and professional ornithologists to track migratory birds. The image below shows a NEXRAD image of the United States. The blue circles reflect the density of flocks of birds, bats, or insects as they migrate over a radar station. By analyzing looping sequences of these and other colorful maps, birders can reasonably forecast the density, location, direction and speed of birds during migration.
Being able to read and understand NEXRAD maps takes a little practice, and bird predictions always rely on some level of groundtruthing, but there are several resources on the web that can help.
The idea is to find a map of a region of the U.S. you are interested in tracking, such as the eastern half of the United States where you can pinpoint the arrival of migrants in the Gulf shore states and watch as the flocks (the blue blobs) move northward in spring (or retreat southward in the fall). Some birders also use NEXRAD to track night migration, thus finding opportune times to go outside at night to listen to nocturnal flight calls.
You can find a good selection of NEXRAD maps at the following links:
Paul Hurtado’s page includes links to other relevant NEXRAD resources, such as the following:
Birds and Radar Primer by BadBirdz Reloaded
This is also a good read:
Understanding Radar and Birds by ebird
Some birders tune into the migration forecasts of certain bloggers, who play the role of “avian weathermen” by narrating what they see in the maps and forecasting what is to come. Indeed, some banding stations and hawkwatches are depending on forecasting like this to plan their staffing needs. While bloggers tend to ebb and flow with their reports, check into these key NEXRAD bloggers for updates.
Armed with the above information, you will well on your way to using NEXRAD as a tool for understanding seasonal migration cycles and can plan your birding trips accordingly.
Give NEXRAD a try. And if you already use radar to predict bird migration in the Rochester area, consider sharing your forecasts with RBA members here on our site.