We’ve flirted with one or two cold fronts so far this season, but last night’s was by far the most powerful. It was part of a storm system that brought tornadoes to Nebraska and more than a foot of snow to the Black Hills. While we won’t see any flurries today, the breezy 50s out there right now are a huge contrast to the breezy 90s from yesterday afternoon. Boom. It’s autumn now.
I assumed there’d be a good number of birds moving either ahead of or just behind this front. I was right, and in a moment I’ll illustrate that the answer was “behind”.
This morning I weaved my way among the bundled sports fans preparing for a crisp day of tailgating and football, and found a Grasshopper Sparrow at the main north entrance and a Lincoln’s Sparrow at the northwestern alcove. This was, as everyone before them, a sad end to these two birds, the official 149th and 150th casualties I’ve documented at the Noble Research Center since August of 2009. Both birds were in immaculate condition, fresh and dry, with fat scores of 3 (Grasshopper) and 1 (Lincoln’s).
The birds’ great condition made it plainly clear that they were traveling behind the cold front that passed through around 2:00 am with thunderstorms, heavy rain, and wind. NEXRAD radar images from last night suggest that these two birds were part of a huge movement through the Plains. Here’s a sample:
The cold front and its line of storms are clearly visible on this image from about 9:20 last night, but note the heavy movement of birds behind the front in Kansas.
By about 1:00 am the storms were finally getting to us in Stillwater, with the heavy flight continuing behind the front.
Now by almost 7:00 am, the storms are well to our east, but that big movement of birds in Kansas has now shifted south, and we see a big movement in Oklahoma. At this point, it is still dark in Stillwater.
By about 8:00 am the movement of migrants has fallen apart as birds on the move overnight have sought a place to put down by daylight. I checked the NRC just after 8:30 am.
So the radar composites seem to confirm my supposition that birds were moving behind this front and put down wherever they could once daylight dawned. As if the two birds I found dead weren’t enough, the tiny strip of juniper hedge on the north side of the NRC held a mixed species flock of probably 50 birds this morning. They looked to be Grasshopper, Lincoln’s, and Clay-colored sparrows, plus at least one warbler that looked like it was probably Orange-crowned.