August 15, 2014:
Spring Migration Songbird Fallout: May 12-13, 2014
On May 13, 2014, I was scheduled to do a count on a private property along the Rio Grande in Embudo. It started snowing in the wee morning hours and was still lightly snowing when I left home to drive to Embudo. I had planned to start the count at 7:00am, but at that time it was snowing hard. From the weather map, it seemed the snow might clear up by 9:00 or so.
Driving out on my road at 8:45, I was surprised to see three birds feeding on the gravel ahead of me. It was completely overcast and at first glance, I thought they must be Canyon Towhee. But as I got closer they clearly were not and when I got my binoculars on them, they appeared to be Hermit Thrush.
The light was poor, but I did get a noisy, out-of-focus picture (see below), which I zoomed on my camera to verify the Hermit Thrush ID.
I thought it was strange to see three Hermit Thrush together like that. They are generally fairly secretive and once seen, usually move into nearby cover and disappear. These three were out in the open, seemed intent on feeding and were not running to hide.
I drove on to Embudo to start my count. The sighting of the three Hermit Thrush seemed odd, but I was focused on getting started on my count and it had dropped out of my thought as I parked my car and started walking across the bridge over the Rio Grande.
By the time I had crossed the water, I had recorded 2 Cassin's Kingbird, a White-breasted Nuthatch, a Black-capped Chickadee, 3 Yellow-rumped Warblers, a lone Canada Goose on the water, an American Crow flying north, and a Say's Phoebe.
As I neared the end of the bridge I noted an Empidonax genus flycatcher in a Russian Olive and then a second one immediately came into view. I usually only see a few Empidonax in a season. Seemed like a very active morning. It was near the peak of the Spring migration, but even so...
As I left the bridge and turned down a dirt road I was amazed to see a Hermit Thrush, no, 2 Hermit Thrush, no, 3, no, 4, 5, 6 in one view. They were spaced out along a 50-yard stretch of the road, feeding just like the three in my road.
It was still snowing lightly and at this point is dawned on me that I was seeing a spring migration "fallout".
A "fallout" occurs when a spring storm forces migrating birds to land unexpectedly. The species involved in this fallout generally migrate at night. When this snowstorm began in the night, the birds were probably forced down wherever they were and once it was light, they found the river and began feeding again to prepare for the next leg of their journey.
During the next 3 hours I would go on to record 12 Hermit Thrush, 5 Gray Flycatcher (one of the Empidonax species) and 18 Unidentified Empidonax. Click Here to see Full List
Unidentified Empidonax Flycatcher Embudo: May 13, 2014 Enlarge
The walk on this count is 1.75 miles one way (downstream). When I make the return trip, I always review what I have seen and see if the numbers seem right. I did that this time, with particular attention to the Hermit Thrush and the flycatchers. I counted a similar number on the return.
There were several other species, though not as numerous, of which I saw my usual yearly number on that day. I often see only one or two MacGilivray's Warbler in a season and only rarely see Vesper Sparrow and Savannah Sparrow. I detected 3 MacGilivray's. I saw one Vesper Sparrow, but heard others and saw one Savannah Sparrow.
By the time I saw the Sparrows, the sky had brightened a bit and I finally got better pictures of the thrush as well as the sparrows:
Hermit Thrush Embudo: May 13, 2014 Enlarge
Savannah Sparrow Embudo: May 13, 2014 Enlarge
Vesper Sparrow Embudo: May 13, 2014
Vesper Sparrow Embudo: May 13, 2014
Finally, on returning to my road about 12:30pm, I counted 5 Hermit Thrush in 0.25 miles, including this one that was feeding in my freshly planted Rye field:
Hermit Thrush Dixon: May 13, 2014 Enlarge
When I got home, there was an email from a friend in Pilar, about 7 miles to the northeast on the Rio Grande: "Three inches of settling, fluffy snow here in Pilar. Here's what's outside my window:
Hermit Thrush (2) under the forsythia, Orange-crowned Warbler, Wilson's Warbler and Virginia's Warbler in the rose bush, Townsend's Warbler (female) and two Yellow-Rumped Warbler in the Pinon, Bullock's male & female at the hummingbird feeder, Black-chinned and Broad-tailed hummers..."
In the next email: "Whoops! Forgot the UEFL!" (UEFL is the four-letter code for Unididentified Empidonax Flycatcher.)
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