Night Migration


I have read about observing bird migration via weather radar, and thought it might be interesting to see what showed up on the Doppler Radar station located on Biorka Island. The animated .gif shown above is color-coded by the velocity of objects the radar ‘sees’ relative to the radar station. Green indicates objects travelling towards the radar station, red indicates objects travelling away, and gray suggesting little or no change in distance (though this does not necessarily imply things are stationary). The time of each frame is indicated at the top, with the sequence starting right around sunset tonight.

As best I can tell from where I am, it’s partly cloudy and there is no rain near town. So, if I am interpreting things correctly, shortly after sunset, migrating birds took off and started flying south. This is suggested by the green dots (travelling toward Biorka) appearing north of Biorka Island with gray/red (travelling away) to the south. It would seem a bit odd for there to be only the narrow band of travel, but the topography of the islands restricts the radar’s ability to detect what is in the air. The peaks of Baranof Island to the east, and Mt. Edgecumbe to the North/Northwest both create shadows.

To see the most current radar image loop visit: the National Weather Service Biorka Island page.

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