Birds Burst Into The Sky After Sunset

Immature male rose-breasted grosbeak (photo from Wikimedia Commons)

19 September 2020

Birding in Pittsburgh has been great this week and will continue today and tomorrow, Saturday & Sunday 19-20 September, as shown on BirdCast’s local migration alert for Pittsburgh below.

screenshot of BirdCast local migration alert for Pittsburgh, PA, 18 Sept 2020

Birding is great on the morning after high migration because the birds travel at night. They start their journey after sunset and land before sunrise, flying over us when it’s too dark to see them.

On good weather nights they’re so anxious to leave that they burst into the sky after sunset, a phenomenon that’s visible on time lapse weather radar. The slideshow below shows this effect on the evening of 15 September 2020 when the birds took off only 20 mins after sunset.

Note that the image is circular because the radar’s reach is circular and it is fainter on the edges because radar fades as it gets far from the source.

Who was flying that night? In addition to warblers, which will be waning soon, we now see thrushes, tanagers, and rose-breasted grosbeaks (Pheucticus ludovicianus). The grosbeaks may resemble females, but don’t be fooled. If they have a touch of orange or red color on their breast they are immature males as shown at top. Here’s another immature male.

Immature male rose-breasted grosbeak (photo from Wikimedia Commons)

This weekend is a great time to go birding in Pittsburgh. Let’s get outdoors!

p.s. Click here to get BirdCast local migration alerts for your hometown.

(photos from Wikimedia Commons, slideshow from KPIT weather radar, Migration alert screenshot from BirdCast; click on the captions to see the originals)

1 thought on “Birds Burst Into The Sky After Sunset

  1. The weather radar also has an azimuth setting – that is: the radar tilts upward at a varying angle. So the radar beam goes higher the farther away from the radar site it extends. This also adds to the loss of signal return.

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