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Who, but Evolution, would paint with feathers?
For these instructions, use the site http://weather.rap.ucar.edu/radar/
Set the Product to 0.5° Velocity, set the end time to 1100 UTC (7 AM EDT), and set the loop for 12 hours. Then click the nearest logo to you on the map (for Portland, Maine click GYX, which is the regional radar unit in Gray, Maine). As the radar frames appear, time is displayed with each frame; subtract four hours for EDT.
On clear nights, you should see signals appear just after sundown, with red pixels from objects moving away from radar (in Gray, at center), and blue from things moving towards. Birds are migrating from blue towards red. The flow of birds is continuous across the field of the radar, so the signals themselves do not appear to be moving.
Anticipating Good Birding Days
If birds are moving through at night, you can expect to see migrants the next day in woods, parks, or bird-friendly back yards. But especially good birding sometimes occurs after night nights in which weather moves in (stronger signal, like usual weather radar) during the night, with the bird signal dropping off ahead of the weather and not coming up again. This might mean that the birds did not reach their habitat targets, and just dropped willy-nilly where they could, often into such as wooded parks (like Evergreen Cemetery in Portland, Maine), where they will stay the day and be quite active -- as in hungry.
Notes
• Signals do not fill the circle because the radar is on a 100-foot tower, tilted upwards slightly (0.5°). Out near the perimeter, radar is looking above the birds (about 500 feet, I estimate).
• If you got satisfactory results with these instructions, go back to the radar site and play around with other operations. For example, "Reflectivity" shows the density of objects reflecting the radar, but does not color them by velocity, and "Regional reflectivity" lets you see larger areas, although long time periods can be slow to load. Try looking at single time frames from the middle of the night.
• These instructions are just a nudge to get you started. I welcome suggestions.
Examples
Here are videos of overnight radar from National Weather Service weather radar in Gray, Maine on two different nights. One of these nights was clear and dry, with heavy bird migration, while the other was rainy all night and few birds were in evidence on radar. Can you tell which night had the heavy migration?
23-24 April 2018
25-26 April 2018
AnswerBirds were migrating on 25-26 April. The radar signals did not "move in" from the west, as did the rain on 23-24 April, but instead simply "blossomed" as birds lifted off all over the radar field around sunset. The flow of birds across the viewing area was continuous until around sunrise 26 April, when the signals disappeared. Note that some rain was moving onto the radar from the west by morning, but was not close enough to drive the birds to ground. So the birds probably reached habitat targets. Birdwatching should have been pretty good on the morning of 26 April, but not spectacular, because birds had the chance to find appropriate habitats rather than just stopping at random, which means diving into the nearest dark environments like Evergreen Cemetery and the surrounding woods.
* © Ryan Shain | McCauley Library
Massachusetts, 2013
