Robo-Birding – Doppler Radar and Migratory Birds

For ages people debated the origins and movements of migratory birds. Bird migrations and movements were recognized as long as 3000 years ago by Homer, Aristotle, and others. Aristotle believed that many birds hibernated, a misconception that continued into the 1800s. Ornithologists debated whether or not birds were capable of flight across the Gulf of Mexico well in the 1960s. A few speculated that hummingbirds must hitchhike on the backs of other migrant birds such as waterfowl. Simply put, we gave birds far too little credit for their capacity to fly.

Modern technology is radically altering our knowledge of birds and their migrations. Now scientists are able to place tiny transmitters on migrant birds, and track them during their flights with satellites. The image below is a compilation of satellite-tracked bar-tailed godwits, one of the longest distance migrants in the world.

Bar-tailed godwit migration

Another useful tool for monitoring migration is Doppler radar. The Doppler system is mainly used for weather, but the radar is equally effective for tracking virtually anything that flies. Birds, bat, and insects all appear in Doppler images. A trained eye can separate the flocks of birds from the other fliers, allowing us to determine (in general) the extent, path, and velocity of migrating birds.

Doppler radar images are available to the general public. At BTB we are using NEXRAD feeds from Weather Underground to follow migration along our stretch of Lake Michigan. Now that spring migrant is upon us, we will regularly update the blog as to what we are seeing and where.

Of particular interest to birders are those rare moments when birds mass along the lake shore due to inclement weather. The ideal conditions consist of two or three days of strong southerly flows, followed by a quick shift to northerly winds due to a late season cold front. The numbers of birds will continue to build along the lake shore as they wait for favorable conditions (i.e., a tail wind and no precipitation). We will alert our readers as we see these conditions developing.

We also need help from you in ground truthing what we see on Doppler. Please send you sightings to eBird, and copy our blog with your bird list for that day. The combination of social media (Twitter, Facebook), eBird, Doppler, and other high-tech tools (such as ARDs, or autonomous recording devices) represent the cutting edge in 21st century wildlife observation. Welcome to the age of robo-birding!

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