"You can observe a lot just by watching." - Yogi Berra
(On Sat, May 3, I wrote this info down in my Field Notes notebook, but I don't think that I recorded it at JotHut.)
At 10:47 a.m., I observed a Hermit Thrush foraging on our back lawn, near the middle oval flower bed, and it used the "shaky leg" foraging technique.
When a HETH forages on the lawn or leaf litter, it will sometimes vertically vibrate one leg that, I assume, is done to flush insects from the ground, so that the HETH can snatch the insects out of the air.
The leg vibration is barely noticeable, and it requires focused observation because it seems that most of the time, this shaky leg foraging technique is not used. Maybe it depends upon how much insect activity is already occurring.
And the bird vibrates only one leg. It will alternate legs though. It will vibrate a leg, move, pause, vibrate the other leg, move, pause, repeat, and snagging insects if successful at flushing them.
The first time that I observed this behavior in a HETH occurred probably around the middle part of the last decade while birdwatching at Magee Marsh. I saw one of the HETH's legs vibrating rapidly, and I thought that the bird's leg was injured. But then the bird moved along the ground, thrush-like, paused, and vibrated its other leg. That's when I realized it was a foraging technique.
After that observation, I watched the HETH's closer, hoping to see the behavior again. It was late in the spring migration for HETH that year, but I observed the behavior in another HETH on another day at Magee, and I've observed the behavior numerous times over the years since.
It's not an obvious leg movement. It can easily go unnoticed if a birdwatcher only looks at the bird long enough to identify it as an HETH. Birdwatching should imply watching the bird for longer periods of time though. But I overlooked this technique for many years. Before I first saw this behavior, I had seen hundreds of HETH in the spring and fall at Magee Marsh, so I was not "watching" the birds close enough.
When foraging in the water, the Snowy Egret moves one leg back and forth, horizontally, trying to attract a small fish with its bright yellow-colored feet.
The HETH moves one leg at a time vertically, very fast. More like a vibration. But I have not found any literature online nor in my books about this foraging technique. I even searched the Cornell Lab of Ornithology's Birds of North America documentation.
It's amazing what we can learn when we slow down long enough to observe what we are looking at.
#todo - finish editing
At-home Birdwatching Notes for Mon morning, May 12, 2014 - May 27, 2014
Backyard Tall Coreopsis flowers - 2013 - Jan 15, 2014
Golden-crowned Kinglet - Aug 30, 2013
Notes - May 16-18, 2014 - May 27, 2014
Aug 2015 bird obs - Aug 26, 2015