Springtime heralds the breeding season for Bonaire’s terns.
Love is in the air, but no, we are not discussing whether Bonaire’s Royals, King Willem-Alexander and Queen Maxima, are expecting! Instead, we are referring to Bonaire’s Royal Terns, as well as other species of terns found on Bonaire.
Springtime on Bonaire, as in many other locations around the world, signals the breeding season for many animals. Bonaire’s population of terns, usually made up of Royal Terns, Caspian Terns, Least Terns, or Common Terns, and occasionally other species of terns, are also feeling the urge to propagate their species.
On a recent birding excursion to Bonaire’s south leeward coast, I was surprised to see a large number of terns and laughing gulls on a very small piece of dry real estate, just off the side of the road. There were so many seabirds on such a small islet, I had to stop to take a longer look.
Tern courtship includes offerings of fish, dancing, and posturing.
Much to my surprise, I found some real courtship behavior in full swing. The first behavior which caught my attention was the offerings of very fine fish dinners.
Courtship feeding is frequently seen in terns. For instance, in an effort to lure females to their territories in the nesting area, a male tern may carry a fish around the breeding colony and display it to prospective mates. After a pair bond is formed, during the “honeymoon period” the male tern can actually feed the female, and soon thereafter they begin to copulate.
As I watched, I saw many examples of fish being offered, always proffered with the fish crosswise in the mouth, but the females seemed to be playing hard to get, with all offerings ignored. In some cases, the male would fly off to another female on the islet to see if he could find a more willing prospective mate.
The size of the proffered fish might be a determining factor as to whether the female accepts the food or not. In an older study of Royal Terns in another location than Bonaire, on 23 occasions in which the female accepted the food, the proffered fish was 7 cm. in length or longer. In seven refusals of food, the fish was only 5 cm in length or smaller and very slender. This leads to speculation that the function of courtship feeding may give the females the opportunity to assess potential mates as future providers for chicks.
Males were busy with other courtship displays, including some high-stepping “Happy Feet” dancing in front of females, as well as unmistakable posturing of the male, with his neck extended and slightly back, and with the bends of the wings out like a skirt.
I was enthralled by the show these seabirds were putting on for me, and several other cars with visitors pulled off to the side of road and joined me in watching. It should be said that any time you are observing nesting birds on Bonaire, it is best to keep your distance and use a spotting scope or binoculars. This is for the safety of the future chicks, as, should your motions scare the nesting female off the nest, the egg could be preyed upon, or even over heat and cook under Bonaire’s sun.
However, after about an hour, in which I did not see one female accept an offer of food, I continued on my way.
New chicks are on the way.
But I was curious to see what the outcome would be, so I visited the islet again the next day. Although about 30% less populated, those remaining were very busy with some real courtship! It seems the females’ defenses came down within those 24 hours, and copulation was repeatedly occurring. When looking closer through binoculars, I could already see some eggs laid in the nesting colony, so we should expect to see some tern chicks in coming days.
So what is the moral of this story? I would normally encourage everyone to stop and smell the roses, but since roses are not common on Bonaire, I will instead encourage everyone to stop and watch the terns courting! Keep your eyes open whenever you are driving around Bonaire as you never know what royal experience you may encounter in Bonaire’s nature.
(Source: Bonaire Insider Reporter, Stanford University, Searchable Ornithological Research Archive – UNM)
Susan Davis has been living on Bonaire for over 25 years. She is a PADI Master Instructor, and an underwater and topside photographer. She also enjoys writing for The Bonaire Insider tourism news blog.