[Tweeters] Pied-billed Grebe behavior

[Constance Sidles]

Dear Nancy, Lucky you, to be on hand to film courtship behavior that is seldom seen, much less recorded.

I believe what's going on in your video is actually a fight between two rival maless while the female (not in video) looks on. Eventually, one of the males believes it has been defeated, and it leaves.

Here is what the Cornell Lab of Ornithology says about this behavior:

During aggressive encounters on territorial boundaries, both intruder and defender, usually males, perform Circle Display. Birds initially are several meters apart. Both hold head high, horizontal and slightly back; crown feathers are “normal” or slightly raised. Black throat area distended. Sometimes white breast partly exposed. Folded wings raised above back. Holding paddling feet out to sides, birds make 180° turns, back and forth, pausing momentarily at end of each turn, sides toward one another. Turning not necessarily synchronized. Possible difference in tail posture, either sticking straight up or up at an angle, and its meaning, need more research. One or both birds may partly open bill, showing tongue. Birds perform head-flicks and wing-quivering (rapidly vibrate slightly open wings,)
Circle Display ends when birds gradually drift away from territories; eventually one or both perform swimming-shake. Alternatively, both birds may draw closer until breasts touch, at which point turning ceases. A “staring contest” follows, lasting up to 6 min. Birds may back off and end interaction, back off and repeat all previous behavior, or start fighting. Prolonged breast contact and staring not reported for any other grebe....

Circle Display during Pied-billed Grebe territorial disputes is similar to that during courtship (see Sexual behavior, below).

From MJM. Neighboring birds' territorial Circle Display may be interrupted with Bluff Diving, a series of in-place dives and resurfacing by 1 bird ( medialink <>). Both birds stretch necks up, hold head horizontal, raise crown feathers, distend throat, and slightly raise folded wings. One sticks tail up, the other suddenly sleeks body feathers and dives head-forward in a Bluff Dive (see Locomotion, above). “Surface” bird maintains position and immediately flattens crown feathers when rival submerges, but does not contract black throat area. May cock head sideways as if looking down, perhaps to watch submerged bird. Submerged bird surfaces after a few seconds in slow, deliberate fashion, in almost same spot where it dived, its crown feathers flat, neck retracted, black throat area distended, and bill pointed at “surface” bird. Sometimes resurfacing bird at first sticks only head and neck out of water. As soon as submerged bird reappears, “surface” bird, looking at surfacing bird, raises its crown feathers. This series of events not seen to lead to fighting. Birds gradually retreat from each other, away from territories, or out into open water, where excitement subsides.

***************

P.S. Much of this information about Pied-billed Grebes was supplied by our very own Martin Muller, a world-class birder and an expert on Pied-billed Grebes. - Connie



> On May 13, 2023, at 3:23 PM, Nancy Morrison <weedsrus1 at gmail.com> wrote:

> 

> I watched two Pied-billed Grebe doing an interesting courtship behavior, but I am confused because one bird was already nesting with another bird. I loaded the video onto YouTube with the hopes that someone can explain what is happening.

> 

> Thank you.

> 

> https://www.youtube.com/watch?v=KQFc912nfeI&t=1s

> 

> Nancy Morrison

> _______________________________________________

> Tweeters mailing list

> Tweeters at u.washington.edu

> http://mailman11.u.washington.edu/mailman/listinfo/tweeters


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman11.u.washington.edu/pipermail/tweeters/attachments/20230513/aa1f78d6/attachment.html>