[Tweeters] [Nancy Morrison & Constance Sidles] Pied-billed Grebe bahavior

[Martin Muller]

Nancy,

Thanks for sharing your excellent video of the Pied-billed Grebes (https://www.youtube.com/watch?v=KQFc912nfeI&t=1s <https://www.youtube.com/watch?v=KQFc912nfeI&t=1s>).

Connie,

Thanks for quoting the Cornell (Birds of the World) information on this.

I’m slow in responding because I am on digest mode for Tweeters.
Several people alerted me to the video privately, as well.

I’ve looked at the video several times (probably a dozen by now). Back when I watched Pied-bills nest under semi-colonial circumstances on Green Lake (late-80s to early-90s) this Circle Display was most often seen between neighboring males on the border of their territories.

This particular duo shows some behavior I had not seen in Circle Display before. The repeated Swimming Shakes (when they rear up and shake their whole body with the body feathers fluffed up) and the short head-backwards movements, which to me looks reminiscent of when they are oiling their feathers and use their head to rub oil onto their back and wing feathers.

Both the head-rub and the Swimming Shake are part of self maintenance behavior (bathing, preening, etc.). Usually when that kind of behavior is stylized and used during displays, it has an appeasing function. Bathing and preening are not associated with fighting. So in my mind these signals are used to mediate the aggressive signals they are sending, including distended throat, fluffed out neck, slightly raised wings, being in close proximity (even brushing their tails up against the opponent during turns (“he started it, he touched me!”)), staring & pointing the bill (= weapon) at one another. The birds are conflicted (they are each at the edge of their defended territory), and so they are sending mixed signals.

A very similar display can be performed during early courtship, between a male and a female (usually only in new pairs). However, in this case the birds are very similar in size, and their bills are almost exactly the same size. Female Pied-billed Grebes have on average 10% smaller bodies than males and especially the depth (height) of the bill is less. If you freeze the video during instances when the bills are in the same plane/orientation, they appear almost exactly the same size (although the position of the surrounding feathers can make them appear different sizes).

Just like Connie said, my money is on territorial display too.

I would urge you to upload this video to the Macaulay Library (https://www.macaulaylibrary.org). Out of the 185 videos of Pied-billed Grebes, only one shows Circle Display. Your extended, high quality video, would be a valuable addition. Make sure to add Territorial Circle Display in the description.

I’m going to watch it one more time….

Martin Muller, Seattle
martinmuller at msn.com





> 

> From: Nancy Morrison <weedsrus1 at gmail.com <mailto:weedsrus1 at gmail.com>>

> Subject: [Tweeters] Pied-billed Grebe behavior

> Date: May 13, 2023 at 3:23:19 PM PDT

> To: tweeters at u.washington.edu <mailto:tweeters at u.washington.edu>

> 

> 

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

> 

> Nancy Morrison

> 

> 

> 

> 

> 

> 

> 

> From: Constance Sidles <constancesidles at gmail.com <mailto:constancesidles at gmail.com>>

> Subject: Re: [Tweeters] Pied-billed Grebe behavior

> Date: May 13, 2023 at 10:16:45 PM PDT

> To: Nancy Morrison <weedsrus1 at gmail.com <mailto:weedsrus1 at gmail.com>>

> Cc: Tweeters <tweeters at u.washington.edu <mailto:tweeters at u.washington.edu>>

> 

> 

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

>> 

>> Nancy Morrison

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