An amusing and highly effective feeding technique.
For the last few years our drought and shrinking Great Salt Lake have greatly reduced the number of brine flies along the shores of the lake, so it’s been a while since I’ve been able to observe this fun and very efficient gull feeding behavior. But this year water levels have risen, brine flies have returned and the gulls are at it again.
Two days ago along the Antelope Island Causeway I was able to document it with photos.
This Franklin’s Gull was one of its more effective practitioners. Those darker colored bands along the shore are composed of unimaginable numbers of brine flies. When predators aren’t actively feeding on them the flies mostly stay on the sand near the water, as you see here.
The gull had a feather stuck to its bill and that feather stayed stuck for almost the entire time I was with the bird. It can be seen in some of my photos and in other photos it can’t.
The gull would face one direction along the length of the shore and then begin running, which scared up brine flies in huge numbers in front of ‘him’. Most flies only rise a few inches above the sand so when the gull would lower his head, most of the flies would be…
just about at mouth level. As he ran through the clouds of flies with his beak open, he was able to…
scoop up large numbers of flies with each running step. I think of this feeding technique as “bucket-mouthing”. You can call it what you like.
Several gulls of different species had a patch of shore staked out so when this guy would reach the end of his hunting patch he would…
turn around and run the other way, scooping up flies as he ran.
This California Gull (I believe) had the hunting patch immediately to the west and this bird was using the same technique to great effect.
This Willet had the hunting patch immediately to the east of the Franklin’s Gull. Willets have apparently never learned this hunting technique (bill gape too narrow for it to be effective?) but this bird was obviously watching the gulls and seemed to be trying to figure out how it’s done. I watched as the Willet ran back and forth through the flies several times but as far as I could tell it never lowered its head or opened its bill in an attempt to scoop up flies as it ran.
Maybe this bird just got a kick out of scaring up flies. I know I’ve done the same thing, for that very reason.
Over the years I’ve only seen gulls “bucket-mouthing” brine flies as they ran through them. Most other birds pick them off individually, as the flies are in flight or on the shore or floating on the water.
Ron
I love seeing the Franklin’s gulls. It’s so wonderful to see this behavior again! It was very frightening the year only a few sickly flies were found by biologist looking for them. Last trip I was thrilled to watch the phalaropes. Usually they spin and stomp in the shallow water to bring up food from the mud. There are so many flies floating on the water and along the shore the phalaropes merely reached out a their beak and snapped up flies. The sound of thousands of snapping beaks is amazing. I want to go back Monday and get more shots of the birds eating brine flies and the orb weaver spiders. I hope the morning is a bit cooler! The heat waves are so visible off the warming sand.
April, I was amazed that I had no trouble with heat waves that morning, even though it got hot. Every last one of my photos that should have been sharp, was sharp. That’s never happened before.
What an effective and energy saving technique. With those sort of numbers the gulls probably don’t even need to swallow…
“the gulls probably don’t even need to swallow”
Especially if they’re running fast enough. And they do run fast.
Gulls are pretty clever little a$$holes — right up there next to crows and ravens. I do feel bad for the little Willet using up energy without getting any return on it. In any event, Woot! Woot! for there being enough water in the GSL to result in that many brine flies. 😃
“Gulls are pretty clever little a$$holes”
Marty, in my book that’s almost perfectly said. Although I might add “thieving” in front of a$$holes. Don’t get me wrong, I admire them for doing so well what works for them but most of them are still inveterate thieves… 🙂
I always thought it was, “The Thieving Magpie,” (I guess it’s just “The Magpie Hat”). 😉
And because I can: https://www.youtube.com/watch?v=CJiiBq8UnIY 😈
It’s a shared trait.
It takes more than a link like that one to pound “culture” into me.
Should I have put up the link to “A Clockwork Orange” theme music instead? 😉
Well, at least that one has a connection to British royalty. You know me and my English heritage…
Although I’ve never been to the great salt lake, I frequently visit mono lake where the same behavior probably exists and now I know to look for it!
Pat, I’d be interested in knowing if and when you observe similar behavior at Mono Lake.
What an interesting thing! And neat that the birds respect their staked out borders! So glad the lake level is high enough for the flies to be back. I remember an article about GSL not too long ago – the biologists walking along the dry sections and not a single brine fly.
Thanks, Carolyn. I believe I saw that same article.
Hilarious! But also a way to get enough tiny brine flies to make a meal. 🙂
Still doing the heat thing. UGH! We only have a small AC in one bedroom which doesn’t get the job done.
Glad we don’t have a martyr situation on our hands – this is bad enough.
Judy, it takes a lot of these flies to fill up even a small bird.
Bad enough indeed.
What an educational post Ron. I don’t think I have ever seen brine flies or if so certainly not in clouds like that. Your photos show that so clearly. Birds who eat these things would get more than they would ever need just by opening their mouths. Glad to hear these are not biting flies.
Thanks, Everett. Those flies supply a glut of food for birds this time of year.
I am very glad the brine flies are back. I am glad I am not there..
Take Care,
Kaye
Kaye, I’m glad they’re back too. Brine flies are no bother to humans at all. The biting gnats on the island are another story.