By now, thanks to the wonder of what I call “news churn,” just about everyone on the planet not obsessed with Kim Kardashian’s wedding has heard about the bird-eating Nepenthes in the UK. The Sun ran with it, the BBC ran with it, and surprisingly the Central Somerset Gazette has the only reasonably complete account of the situation. This is how I know I have friends who love me: I had literally dozens of well-intentioned friends E-mailing and calling me to let me know about the BBC article. I’ve also literally had to bite my tongue in one case to keep from yelling “YES, WE’VE GOT A VIDEO!”
Now, what’s really illuminating about this story isn’t that a blue tit was caught in a pitcher plant. Carnivorous plants capturing vertebrates is rare, but it occasionally happens. The Carnivorous Plant Newsletter featured a cover a while back of a Venus flytrap with a baby anole caught in its trap, with only rear legs and tail hanging outside. Sundews are very good at catching newly metamorphosed frogs, and the protocarnivore Roridula has been documented capturing small birds. The widest range of vertebrate carnivory, though, is with the Nepenthes pitcher plants, ranging from frogs to lizards to rodents and even (anecdotally) baby monkeys.
I want to add, at this point, that many of these presumed cases of carnivory are probably accidental. Frog skeletons occasionally show up in Sarracenia and Nepenthes traps, but those are probably frogs using the traps as handy hunting sites that died of natural causes. The rodents found in particularly big Nepenthes were probably attracted by the traps’ fluid as something to drink, and this blue tit was probably trying to steal prey out of the trap when it found itself stuck inside. The surprise isn’t that the plant could catch a bird, but that the bird was so unlucky as to get caught in this situation.
If anything, this story demonstrates what happens when carnivores get prey too big for them to digest before it rots. Carnivores generally have no way to chew or otherwise process larger prey, and many species take advantage of animals that either remove large dead items or take over the job of digestion. In America, you have green tree frogs that camp inside of Sarracenia pitchers, snagging really large prey attracted to the plant and then defecating inside the pitchers: the plants don’t care about the source of nitrogen they’re receiving. In South America, Heliamphora pitchers work well as campgrounds for indigenous frogs as well. Spiders and other arthropod predators have no problem with snagging large prey, and one species, Misumenops nepenthicola, lives inside the pitchers and has special adaptations for dealing with the pitcher fluid.
The other aspect of the story that’s neglected involves Nigel Hewitt-Cooper, who’s already understandably respected for his plants. I first heard about him not just because of his gold medals for entries at the RHS Chelsea Flower Show, but because of his position as councillor of Croscombe and Pilton. He’s a very interesting fellow all the way around, and one day, I’m going to the Chelsea Flower Show just to meet him in person.