Migration Update: Again with the traffic reports . . .

Andrew Farnsworth The Cornell Lab Aug 30, 2016

Last year, BirdCast brought you its own version of rubber necking (warbler necking?) and fender benders (fallouts?) with our Traffic Report posts. This fall, we will be at it again . . .

Each night, from local sunset to local sunrise in the Eastern time zone, a BirdCast server downloads radar data from 16 stations in the northeastern US. These data are composed of every scan of the atmosphere made by these radars during this time period, with a particular focus in our case on radar reflectivity products representing the magnitude of targets (whether meteorological, like rain and hail, or biological, like birds, bats, and insects) at a given radar. A pipeline of algorithms extracts information from these radar data about birds, and the resulting bird-specific summary imagery is published daily in early afternoon eastern time (give or take).

The images you see in Traffic Reports present the migration traffic rate (MTR), direction of bird movement, and speed of bird movement. These presentations have not been reviewed by an expert, instead representing the automated output from several algorithms. Errors in the metrics are possible for approximately ~5-8% radar scans. These errors most frequently manifest as incorrect classification of precipitation or other non-biological information as birds by our automated classifier during nights with both migration and precipitation present.

For detailed information on the processing and quantification of radar data and the algorithms involved in this processing pipeline, please see our recent publication in Ecological Applications.

Several quiet nights begin this animation, with little to no movement apparent for the entirety of the region. But the night of 26 and 27 August see marked changes, with significant flights toward the south and southwest. These flights were particularly large over more inland locations from central New York south and west into West Virginia on 26 August and over Maine on 27 August.

Please check our Traffic Reports tab each week for accounts that complement our regional migration forecasts.