Terns Bio-Clocks Tick Loudly


Above the male mounted on top of the female who has something to say.
Above the male mounted on top of the female who has something to say.

Longboat Key, Florida

April 14, 2014


April is the mating season for royal terns and sandwich terns on Longboat Key. During the first two weeks of April I observed 60-matings. Despite being a seasoned observer, I’d never before witnessed anything like this. I was the proverbial kid in a candy store. Most of the couplings that I witnessed were full matings that lasted about three minutes. Some were partial matings and others were aborted attempts. Overwhelmingly it was royal terns mating although I saw three pair of sandwich terns doing so.

All the matings occurred with a large group of birds, never on an isolated part of the beach or outside of the group. Once when I was getting off the beach, terns were packed in a forty yard stretch. Sounds abounded. A chorus of trilling and squawking by the group which often preceded a mating could be heard. However there also was a different sound. A high insistent call that sounded like an alarm clock that just wouldn’t stop. It was the sound of the biological clocks of royal terns raging to mate; their bio-clocks ticking loudly.

Signs of The Season

Two signs of the mating season are visible in March. The first is that the royal terns start to walk around with their wing joints slightly separated from their bodies. They often face or stay near others whose wings are similarly held. A beach friend likens them to weight lifters strutting around displaying their muscles.


The second sign is that some of the sandwich terns get a pink hue on their breasts. It took me several years to see that this wasn’t an optical illusion created by the sun. One cloudy afternoon I saw two sandwiches standing side by side; one had it, the other didn’t. This year I saw two laughing gulls that had the same pinkish hue and one royal tern that when preening itself, showed a red area that possibly was the same thing.

The pre-courtship process begins with one royal walking over to another. If no interest is shown the initiator walks away. Among the royals, no means no. No royal that I ever saw rejected, tried to impose its will on the rejector. I’ve seen very brief attempts that were aborted in seconds. Once I saw a male jump onto a female’s back. He was facing partially backwards. All mating occurs when the partners’ heads are facing forward. She walked away with him trying to right himself. No interest. He hopped off. Walking away also ends many of the full matings that I’ve observed.



Unraveling A Mystery

The actual courtship process begins when one tern, with wing joints held out, walks counterclockwise around another tern.  Once my wife and I saw a gentle touching of the bird being walked around and a full mating ensued. In lightning-like fashion the male hopped on her back.


Initially what we saw in a number of attempts was the male standing on the female’s back. I wondered if these were real matings or “practice” because other than the male’s feet touching the female’s upper back there was no bodily touching. There was much wing beating and noise made by the male. However what was happening remained a mystery. I wanted pictures and found plenty of opportunity.


One morning matings were breaking out all over. See a royal flapping its wings and it‘s likely to be on top of a female’s back. Two matings occurred at once. As one ended another started right in front of me! I went back and forth taking pictures. Literally seconds after one of the matings ended, the male hopped on her back again and stayed a long time. When my wife and I viewed pics on the computer, the mystery was solved in numerous “Kodak moments.”


In front side and rear pics the male would be mounted near her rump which was partially raised and her wings would be further out and back surrounding, but not touching, his body. That’s when the wing flapping ensued. In other pics his rear is pressed against hers with much wing flapping. This is no doubt where bodily fluids meet. I would guesstimate that he goes back and forth three times during a normal mating.


Overwhelmingly the male is not an aggressor nor is the female passive; theirs is a partnership. I watched once as one bird approached and began “chirping” to another. To my surprise it was the silent party who hopped aboard. The female had initiated the mating. At times I’ve seen the female with the male on top, tap the ground with her bill. One morning I saw a female tap twice and after one of those taps he moved to her rear. This was clearly symbolic communication.


There were however instances of unwanted aggression. As every mating occurred in a large group setting where hormones were on high alert, mating pairs weren’t always left in connubial bliss. On one occasion I saw a royal aggressively approach a mating pair. The coupling male had to fend off the intruder and the pair managed to finish. In another case two aggressive royals, which I assume were males, approached. This was too much and it ended the wingding. On another occasion after a male jumped off a female, another male started to jump on and was chased by the male that had just gotten off.


Most matings were the same, yet everyone was different. The closer I looked, the more I saw. On the flight home reviewing my notes I found some things that I only dimly remembered. Among them were three references to male royals making an “uh, uh, uh, uh” clacking noise all the way through a mating  Days later I’m still emotionally processing the whole experience. However one thing doesn’t need processing: when royal terns bio-clocks race, they are loud.


Michael Givant
Michael Givant is a columnist for Anton Media Group. His column A Bird's Eye View is popular among local birdwatchers and photographers.

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