In a recent post about chestnut-headed oropendolas, I promised to get back to you with better (published) information, and after some searching found The Nesting Habits of Wagler’s Oropendola (Zarhynchus wagleri) On Barro Colorado Island, from the Bulletin of the American Museum of Natural History (1928, Vol. LVIII). Ornithologist Frank M. Chapman sat in a camp chair on BCI and watched a colony at work in a sandbox tree (Hura crepitans). He wrote with great charm about, among other things, the male oropendola’s unusual song:
The courtship, or”crash”call, which I consider the male’s real song, begins with the one just described and adds a sputtering crackle ending in an explosive crash. In my notes I have also termed this remarkable production a sputtering, masticatory, ejaculation.
…and what the bird has to go through to produce it:
It can, indeed, be seen coming as the bird’s body begins to swell from below upward and, rising on tip-toe, he delivers his vocal appeal, then sinks back deflated.
This video I took of the BCI colony shows some of what the male’s display looks like. But really, you just want to see his pretty blue eyes.
Chapman’s paper is full of natural history observation and whimsical asides you rarely see in science papers, written in a narrative form about one colony, and no graphs to slow down the storyline. But that’s not all.
Chapman watched his oropendola colony on Barro Colorado Island, where its long nests hung from a tree beside the laboratory building (now the visitor center). Where did I sketch my oropendola colony? Same spot.
Of all the chestnut-headed oropendola colonies in the world, I had to go and sketch Frank’s.