Weather and Songbird Migration: March 29, 2017
By Dr. David Aborn

Southerly Winds Bring Big Numbers North!
Tree swallow
Tree swallow
JanetandPhil (CC BY-NC-ND 2.0)

NEXRAD and Migration
Birds on NEXRAD
Wilson's warbler
Julio Mulero(CC BY-NC-ND 2.0)

Weather Map
Weather Map
Ornithologist Dr. David Aborn  

Dear Journey North,

Last week I mentioned that there was the possibility of a fallout as a cold front moved across the country. That didn’t happen, but there was a still a lot of migration taking place.

Favorable Winds Bring Big Numbers
Southerly winds in recent days have helped migrants make good progress on their north-bound journey. There have been certain species that were particularly numerous in many places. Blue-headed Vireos, Black-throated-green Warblers, Black-and-white Warblers, Northern Parulas, and especially Louisiana Waterthrushes were all reported in big numbers from the Gulf coast up to Maryland and into Missouri and Ohio. The southerly winds pushed some of the earlier migrants even farther, with the first Tree Swallows showing up in New York and Minnesota.

Watch Birds Take Off on NEXRAD
To visualize all this occurring, we can turn to another weather tool; radar. Modern NEXRAD radar is sensitive enough to pick up migrants as they take off for a night’s migration. What you'll see on NEXRAD is a bunch of blue circles appear; these are birds taking off on migration! Watch them, it's very cool!

Migrants Push Ahead in the West
In addition to the eastern U.S., the west has also seen a lot of migration over the past week. The first Black-headed Grosbeaks showed up in California, along with Wilson’s Warblers, Orange-crowned Warblers, Western Kingbirds, and Violet-green Swallows. Tree Swallows and Rufus Hummingbirds along with Violet-green Swallows have made it as far as Washington.

"This is when the fun begins!"
So what does the coming week look like? Well, as you can see from both the weather map and the radar, there is a lot of rain in the middle of the country, so those birds won’t be going anywhere for a few days. In the eastern U.S., migrants will still enjoy a couple of more days of clear skies and southerly winds, so I expect a lot of movement until the weekend. By the time the weekend arrives, weather will be favorable for migration in the central and western U.S.

As you can see, however, there is another front coming in from the Pacific, so by the start of next week migrants will have poor flying conditions again.

Things are really getting active, so this is when the fun begins!

Take care,

  • David Aborn
    North Chickamauga Creek Conservancy
    Chattanooga, TN
Next Update: April 5, 2017