After posting a video a few days ago showing a pair of European Herring Gulls (Larus argentatus) displaying the choking behavior, Phil commented:
What are the Herring Gulls doing at 1:15 (and onwards)? Is that some sort of regurgitating motion? I’ve never seen that before in gulls – though I know that parrots will do something similar when pairing up.
Good question, Phil. I’ve been wanting to write a post about this for some time but felt I didn’t have enough examples to show, but now is as good a time as any I guess.
Here’s the video once more:
The behavior displayed at 1:15 (and also at 0:22) is called “choking” and very much resembles a regurgitating motion.
In this display, the gull squats and bends forward with the bill pointed down while the head makes rapid downward movements without touching the ground. As can be seen in the video as well, the tongue bone is lowered, creating a “bulge” in the throat.
During this display, a muffled rhythmical sound is given.
Un-edited recording of a pair of adult Lesser Black-backed Gulls choking, with background noise (camera, car, cyclist). Leiden, The Netherlands, August 2012.
Here’s another video that I found in my archives showing the same display in Lesser Black-backed Gulls (Larus fuscus). It was taken in one of the large gull colonies near the port of Rotterdam in The Netherlands in April 2012:
Here is another one taken in the same colony in May 2012:
And one more of a pair of Lesser Black-backed Gulls:
Read the story behind this scene here.
What is this display for?
Niko Tinbergen in his book The Animal in its World (1972) writes that it is a ritualized display, originating from either depositing nesting material, regurgitation or both.
To my understanding, choking can be displayed in the following contexts:
- As a pair-bonding ritual, as shown in the videos #1, #2 and #4 above.
- In the colony to indicate a possible nesting site to the partner. A good example can be seen in the excellent DVD Signals for Survival (Marc Dantzker and David O. Brown, The Cornell Lab of Ornithology and the Shoals Marine Laboratory, April 1, 2009) which I can highly recommend.
- As hostile behavior towards other pairs within or near the nest or colony (boundary disputes). I have witnessed this twice, although in one instance just two gulls were involved. See the photos below.
How common is this type of behavior in gulls?
This type of behavior is common in all if not most species of gulls, including Kittiwakes. It seems to be often accompanied by mew-calling, especially when the context is pair-bonding.
Here are some references that I found on the internet:
Western Gull (audio)
For me, choking is one of my favorite of gull displays. I couldn’t really believe that this type of behavior occurred in gulls when I first saw it because it looks so out of place.
It is difficult to capture this behavior in photos, but here are some more examples anyway. I hope you enjoy them as much as I do:
Signals for Survival – (DVD) Marc Dantzker and David O. Brown, The Cornell Lab of Ornithology and the Shoals Marine Laboratory, April 1, 2009
The Animal in Its World – Niko Tinbergen, third printing 1975
The Evolution of Behavior in Gulls – Niko Tinbergen (1960)