While my mother was visiting Utah she was able to see how California Gulls chase and feed on Brine Flies, it is fascinating feeding behavior. As my mom watched, I photographed.
The gull starts out standing on the edge of the Great Salt Lake. The Brine Flies can bee seen in this image floating on the hyper saline lake surface.
Then it begins to run and the Brine Flies lift off from the sand and water surface. All of the brown colored specks on the shoreline are the pupal casings of the Brine Flies.
As the gull gains momentum it lifts its wings and more flies take to the air…
Then the gull starts to catch the flies by opening and closing its bill as it runs along.
The Brine Flies fan out in an undulating wave in front of the gull as it races along snatching them from the air
When the flies thin out in front of the bird the gull slow down
And come to a stop.
The gull rests a few moments and begins chasing the Brine Flies again. This frame shows the gull a little further from the shoreline and the flies lifting up from the sand.
Again the gull grabs the flies from the air with its bill.
And comes to a halt again. I have no idea how many flies a California Gull catches when it runs along the shoreline, it would be interesting to know though.
All of these images were taken using my Nikon D300 with my lens resting on my Noodle, f6.3, ISO 500, with shutter speeds ranging from 1/2000 to 1/3200 and all of them were taken using natural light. These images are a challenge to create because at times the camera tries to focus on the mass of flies instead of the bird.
There are more images of California Gulls exhibiting this feeding behavior on this post titled California Gulls feeding on the Brine Flies of the Great Salt Lake.