Possible "group anting" in American Robins? (1 Viewer)

Hello all,

Yesterday evening I observed some very peculiar behavior in my backyard, a behavior that I have not seen before.

Around 18:30 I was alerted to the sight of about 10 robins on the back lawn. Upon closer inspection, I saw that about half of them were preening. However, it was not a normal kind of preening. The robins were spreading their wings and tails out at odd angles, sometimes letting their wings touch the ground. They would first pick at the grass, then they would begin the aforementioned preening behavior. This went on for almost an hour, with most (I believe) engaging in this behavior at some point, even juveniles. By the end of the hour, most were now picking at the grass and eating something.

I suspect they were "anting" for two reasons. First, I can't figure out why they would all deliberately preen in an unusual manner on the ground. Second, I don't think they could have been sunbathing because it was late afternoon/early evening and the sun was not strong.

I can confirm there are a lot of ants in the yard, as many times I have either sat down or set something up in the yard, and ants would start congregating aggressively. This is true for a good portion of the yard.

If they were all "anting", though, why did they do it together and why have I not seen them do it before?

Unfortunately I did not get any pictures showing their behavior.

Thank you in advance for helping me decipher the latest bird "ant-ics" in my yard!

Maybe just a case of "social facilitation"--one starts and the others follow suit?

Round Two

Thanks for replying, fugl.

The story continues... They came back again this evening for Round Two, though to a lesser degree than yesterday.

I observed five American Robins tonight from about 17:55 to 18:25, two of which engaged in this possible "anting" behavior. An adult male seemed to be keeping the numbers down, though I think fewer robins came tonight in the first place. I was able to get several photos of them this time. Though the photos are poor, they give a general idea of the scene and what the robins were doing.

The first four photos show two different birds (I believe) preening, but it demonstrates the strange postures I described in my previous post.

The last photo is simply a photo of most of the group, including one presumably "anting".

Have you tried getting close to the birds when they're engaged in these shenanigans? My experience with sunbathing/anting is that the birds become almost comatose, allowing a very close approach before abruptly snapping out of it and flying off. Getting close in this way would also enable you to check for ants.

Here's a photo I took a couple of years ago of a sunbathing jay which allowed me to get within a few feet before it flew off--
https://www.flickr.com/photos/fugl/18227265704/in/album-72157602221849079/

fugl said:

Have you tried getting close to the birds when they're engaged in these shenanigans? My experience with sunbathing/anting is that the birds become almost comatose, allowing a very close approach before abruptly snapping out of it and flying off. Getting close in this way would also enable you to check for ants.

Here's a photo I took a couple of years ago of a sunbathing jay which allowed me to get within a few feet before it flew off--
https://www.flickr.com/photos/fugl/18227265704/in/album-72157602221849079/

Click to expand...

No, I haven't. If they come back again tonight, I might give that a try!

The robins did not come back for a third installment. I enjoyed it while it lasted, and they might come again another time!

fugl said:

Have you tried getting close to the birds when they're engaged in these shenanigans? My experience with sunbathing/anting is that the birds become almost comatose, allowing a very close approach before abruptly snapping out of it and flying off. Getting close in this way would also enable you to check for ants.

Here's a photo I took a couple of years ago of a sunbathing jay which allowed me to get within a few feet before it flew off--
https://www.flickr.com/photos/fugl/18227265704/in/album-72157602221849079/

Click to expand...

UPDATE:

I saw another robin engaging in this behavior tonight and got a bit closer. Initially it didn't do much, but when I was maybe 15-20 feet from the robin it swiftly hopped away.

I forgot to check for ants...

I've only seen anting being done in the daylight and sunny hours of the day. Never in the evening.