Black Necked Stilts – Mating Rituals And Copulation

Two days ago at Bear River MBR I spotted a male and a female Black-necked Stilt in some shallow standing water close to the road. I wondered if they were a bonded pair but they weren’t close to each other and they seemed to be ignoring each other so I wasn’t sure.

I stopped for them in order to watch their behavior and see if I could tell if they were a mated pair.

 

This is the male. I concentrated on him because the female was in less attractive water that was partially covered with debris. I figured I had a better chance to get reflection shots I liked with the male.

After taking quite a few photos of him he suddenly started to walk briskly toward the female, which is what he’s doing here.

 

 

When he reached her I noticed that she was stirring the water with her bill. I recognized her behavior as a pre-copulatary behavior of the species that is most often performed by the male. I’m not sure I’ve seen females doing it before.

Note: in this species females can be recognized by the brownish tinge on their back and scapulars that males lack.

 

 

He walked around her and watched intently as she shook the tip of her bill in the water. I call it “stirring the water”.

 

 

Then he started to groom his breast feathers (“sexual preening”) as she held a solicitation posture with her head down – both of which I recognized as pre-copulatory behaviors.

 

 

He circled around her as she held the solicitation posture.

 

 

Then he started stirring the water vigorously with his bill. The female never stirred the water again but the male did so almost continuously.

 

 

He walked around her again. Each time he did so he’d stop and stir the water. He circled her at least two more times after this but I’ll spare my readers the repetition by not including more photos of him circling.

 

 

Even though he stirred the water almost constantly, the female never seemed bored by the behavior. Instead, she seemed intently interested in it, to the point of fascination.

 

 

I knew that if nothing interrupted the lovebirds (like another vehicle coming by) he’d eventually mount her to begin copulation but I wasn’t prepared when it happened so…

 

 

when he mounted her I cut off both of his wings.

 

 

He squatted down to rest his tarsometatarsi on her back and fluttered his wings to help maintain his balance on his unstable “perch”.

 

 

This is the moment when the “cloacal kiss” was accomplished. It happened so fast, in the very next shot in the burst he was…

 

 

already dismounting her.

 

 

Next came the few moments that always touch my heart. As they always do, immediately after mating they crossed bills and the male…

 

 

wrapped one wing around his mate in what seems like a tender embrace. Interestingly, when they cross bills the male’s bill always crosses on top of the female’s bill. Never the other way around.

They held this position for a few moments and then…

 

 

it was over. They parted and then they both began to forage for food again, as if nothing had happened. Here it looks like part of the male’s right wing is missing but of course it isn’t.

This was my first observation of mating birds of any species this season. As you can imagine, it made my day.

Ron

 

Note: In case you’re wondering how close the behavior I observed matches known behavior of the species, here’s what Cornell’s Birds of the world has to say about pre and postcopulatory behavior in Black-necked Stilts.

 

“Copulation is a ritualized sequence of displays. Precopulatory Display is initiated by female Solicitation Posture or by male and female Sexual Preening. Female adopts stiff Solicitation Posture: neck extended horizontally forward and feet planted. Male performs Sexual Preening by standing 20 to 30 cm from female, extending his neck and preening his breast on the side facing the female. Water is used in Sexual Preening by shaking bill when placing it in the water and bringing water to the breast in the bill; intensity increases during the course of display, culminating in vigorous splashing immediately prior to mounting the female. Sometimes female also preens. As male Sexual Preening becomes more frenzied, male moves from one side of the female to the other 2–8 times while continuing vigorous preening and water splashing. Female may turn slightly to keep herself aligned parallel to direction of male.

While female holds the Solicitation Posture, male mounts to copulate, resting his tarsometatarsi on her back. Male flutters wings to maintain balance, and cloacal contact is made. Female sometimes moves her head slowly from side to side during copulation.

After male slides off female, pair performs Post-copulatory Display: birds stand side to side with bills crossed and run forward. Male sometimes holds wing over back of female. According to Coleman, the male’s bill always crosses on top of the female’s bill. The pair then separates. Total duration from first sexual preening to separation of the pair after postcopulatory display approximately 1 min.”