Previous: January 2020 article - Bird Language
Imagine if a birder had a magic video camera that could be aimed at the night sky and would show the bird migration patterns all across the country every evening. Imagine also that the images could be enlarged so that a single group of states could fill a screen, and that playback could be sped up, slowed down, or even set to repeat. Clever Cornell Ornithology Labs programmers have imagined these possibilities, and have taken advantage of the weather radar feeds from the US NEXRAD surveillance network to create BirdCast.
Then imagine that decades of such weather radar observations could be utilized to inform not only daily live Migration Maps (a Favorite), but even 3-day forecasts during the main migration seasons. As explained in a comprehensive Cornell Labs tutorial, that's what we've been given. What is perhaps most amazing is that the radar signals are sufficently nuanced to allow analytic discrimination between storm clouds, flocks of birds, and even swarms of insects. While all of these move through the air, they all behave and respond to radar impulses in distinct ways, which BirdCast researchers can distinguish, and the interpretations of which are described in the Scientific Discussions postings on the site.
One set of those Discussions, called Species on The Move seasonally offers migration maps for particular birds in different regions of the country. With graphical mapping techniques similar to those available through eBird's Status and Trends pages, the BirdCast images, when available, are far more detailed. Unlike eBird, which has been developing and expanding since its public release in 2002, BirdCast is very much a work-in-progress, as it was only launched in 2012. The site is in flux, with variable links, and inconsistent, unpredictable resources. But it's well worth exploring. A good place to start is the Review and Interpretation portion of the Research pages, which explains in greater detail how all this information is presented.