Feed me or I’ll die, and possibly take you with me!
Years ago it was pointed out by somebody, probably Tinbergen or Lack or Wynn-Edwards or one of the other great bird-savvy ethologists of the day, that young Pelicans would blackmail their parents by biting their own wings, a very self defeating activity for a bird with a huge and powerful beak. “If you don’t feed me right way, I’m taking off this wing and your reproductive success is done!” they seemed to be saying.
More recently a study of Babblers in South Africa may have demonstrated a similar kind of extortion. We are speaking of the Pied Babbler (Turdoides bicolor) of the Kalahari in South Africa. The babies beg for food while in the nest, but they also jump out of the nest and beg for food while on the ground. When the young birds are begging from the ground, the parents feed them a lot more, seemingly to shut them up. When scientists created a sense of threat by playing another species alarm call, the parents increased their efforts in feeding the grounded birds, but not the birds in the nest. When fledglings were given extra food by the scientists, they were less likely to jump to the ground to engage in this apparent extortion, suggesting that the ground begging behavior was hunger-driven.
There may be other explanations for this behavior, including a simple linkage between foraging (which is not done in the nest) and hunger. Also, as researcher Rufus Johnstone of the University of Cambridge notes, “The question I come away with is whether it’s possible to distinguish between blackmail and honest signalling of hunger.”
A bird in the hand is worth two in the bush. But a baby bird on the ground is just annoying, better stuff something in its mouth.
In other bird science news, we should be concerned about waterfowl in China. The new H7N9 bird flu is probably widespread in birds, because it seems to be poking itself into human populations one person at a time over a very large geographical area. Maybe it is endemic to domestic fowl and is being spread among those birds in markets, but perhaps it is in wild birds, most likely waterfowl, instead or as well. Apparently you can’t identify sick birds … H7N9 is carried by birds but does not seem to bother them. Let us hope that the details are understood soon so that there is no driving of waterfowl into the swamp, as it were.
The blackmailing bird story is here, and discussed further here.