It’s Sunday, and that means another batch of themed bird photos from John Avise, this time involving a strange feeding strategy. John’s notes and IDs are indented, and you can enlarge the pictures by clicking on them. I’ve added two videos at the bottom
Vortex Feeding
Phalaropes are shorebirds with a distinctive foraging mode. When feeding, each bird twirls its body rapidly while swimming on the surface of a body of water, thereby creating a vortex that brings up and concentrates food particles that the birds then eat (the twirling is so rapid that you would think each bird would get very dizzy!). Another kind of “vortex feeding” is displayed by some ducks, who often gather in circular-swimming groups, thereby collectively creating a water vortex that likewise brings up and concentrates edible goodies. Three species of Phalaropes and two duck species that display these vortex-feeding modes are the subject of this week’s post. I took all of these pictures in Southern California.
Wilson’s Phalarope (Phalaropus tricolor):
Wilson’s Phalaropes spin-swimming:
Ripples left by twirling Wilson’s Phalarope:
Red-necked Phalarope (Phalaropus lobatus):
Red-necked Phalarope spin-swimming:
Red Phalarope (Phalaropus fulicaria):
Pair of Northern Shovelers (Anas clypeata):
Group of Northern Shovelers circle-swimming:
Pair of American Wigeons (Anas americana):
Group of American Wigeons circle-swimming:
Multiple groups of American Wigeons circle-swimming:
Here’s a video of Wilson’s phalaropes vortex feeding:
And pink-eared ducks (Malacorhynchus membranaceus) vortex feeding. This is an Australian species.
In haste – great post!
I did not know vortex feeding was a thing. Excellent to know. That innate physics engine!
Great pictures as always, though I felt like lying down after the videos!
Interesting post, and great photos as usual, John Avise. Thank you!
Wow, spinning in one place, versus spinning while moving seems to be a slightly different strategy. I would think staying in place would create a more powerful vortex, but both seemed to doing doing equally well.
The late UCLA ornithologist Bryan Obst deserves a mention here for having done quite a bit of fascinating work on vortex feeding. I saw him give a talk once in which he humorously and insightfully analogized it to both tempests and teacups.