By Joshua Bergmark
Joshua Bergmark is a lifelong birder from Australia and has worked as a professional bird tour leader since he was 16 years old. Now the director of Ornis Birding Expeditions, he spends much of his time guiding tours throughout New Guinea and the Pacific, as well as further afield. Nothing can beat watching bird-of-paradise displays or hiking up into the hills of remote islands in search of poorly-known endemics!
Those who have been to New Guinea in recent years may have been lucky enough to visit specially constructed hides at the bowers of either the Masked Bowerbird in the Arfaks of West Papua or of the closely related Flame Bowerbird in the southern lowlands of Papua New Guinea. The display behavior of both species has been well-documented during recent BBC films (one of their hides we were even able to use on our tour a few years ago!), but I and other bird tour leaders have regularly noted that there is an abnormally high incidence of males being seen destroying or otherwise abandoning their bowers.
Male bowerbirds are known to make their bowers at the start of the breeding season (usually over the course of days or weeks) and spend much of their time very close to their constructions to protect them from other males for the subsequent months. However, at least these two species in the Sericulus genus can go for long periods without attending their bowers on any given day, perhaps to avoid predation due to their insanely vibrant coloration. It is also very common for the bowers to be “active” for a couple of days after a hide has been built, and then fall into disuse, this being especially true for the Masked Bowerbird.
In November 2024, I was taken to a site in the Arfaks during our West Papua Vogelkop tour where the local landowners had found an active Masked Bowerbird bower several days previously. While no hide had been built yet, and there had been no disturbance to the bird, we arrived to find the bower already abandoned. The bower of presumably the same male was found later that day less than a hundred meters away, and we set up a very small hide overnight at a good distance from the construction. I was sitting very quietly in there at dawn and observed a male come in and completely rip apart the entire structure in the span of about ten minutes before flying off. Was it the owner, so sensitive to disturbance that the mere sight of a nearby hide was enough to make him give up? I have seen Flame Bowerbirds do exactly the same thing, and this is an opinion often voiced by the local hide owners, but it had always seemed a strange explanation to me.
An hour later, another male came in with an engorged tick on his face (proving he was a different individual, and this time seemingly the real owner). I watched in complete silence, and in slightly less than sixty minutes he had completely rebuilt the bower from scratch using the broken pile of twigs left lying on the ground. This single session in the hide was very enlightening, and indicated to me that perhaps it is normal for the males to regularly move the position of their bowers, especially since they can clearly rebuild much faster than I had imagined!
Later reading about the congeneric Regent Bowerbird of Australia (the only well-studied Sericulus bowerbird) surprisingly seemed to validate all these hypotheses. One comprehensive study (Lenz 1994) recorded adult males spending only 3.2% of daylight hours at their bower, with damage caused by intruders (both adult males and immature males) frequently leading to the abandonment of a bower by its owner. Lenz also observed rebuilds occurring an average of 64m away, usually finished within a matter of hours. What a contrast to most other species in the family!
All-in-all a very interesting field study of this spectacularly fascinating but still poorly-known New Guinea endemic. He returned the following day and everyone else in the group saw him very nicely, even doing one short display to a female!
Cover Photo: The owner of the construction, a male Masked Bowerbird (Sericulus aureus) has almost finished rebuilding his destroyed bower. Photo by the author.
Leave a Comment