An online report published in last week’s Biology Letters has revealed the damaging effect an invasion of ants (Anoplolepis gracilipes) is having on some of Christmas Island’s native bird and plant species. In this study, led by ecologist, Dennis O’Dowd of Monash University in Melbourne, experiments were carried out to see if the ants’ behaviour inhibited small forrest passerines such as the Christmas Island White-eye and the Island Thrush from eating the produce of the local fleshy-fruited plants.
By setting up equal numbers of model fruit displays and real fruits in areas both cleared of and occupied by the supercolonies of Anoplolepis gracilipes, commonly known as ‘yellow crazy ants’ on account of their erratic reaction when disturbed, the team was able to observe the instances of fruit-handling by the two species of birds in both kinds of environments. Using peck-marks on the 1151 model fruits that were handled by the birds, they found that both the white-eye and the thrush were less likely to approach the fruits in areas inhabited by the yellow crazy ants, with the handling rates up to 2.4 times lower in the ant-invaded areas than those which were ant-free.
As the consumption and handling of fruit is imperative to the reproduction of both the local plants and native birds, a reduction in fruit-handling due to the steadily expanding supercolonies of yellow crazy ants is a conservational concern, especially given that the numbers of Christmas Island red crabs have already been greatly affected by this ant invasion. As O’Dowd observed, the yellow crazy ants would often climb onto the birds, causing them to ruffle their feathers and stomp their feet in an attempt to shake them off, this behaviour proven to be far more deadly where the red crab is concerned, the ants known to swarm over the crabs, spray them with formic acid, and bite them to death.
So I can kind of see where the white-eyes and red crabs are coming from. It’s not like either of them are known for being particularly short-tempered creatures, so if they say the yellow crazy ants – or YELLOW KRAZEE ANTZ, as they prefer to be called – are insufferable, I’m willing to bet they are. Like, a Christmas Island White-eye will be quietly wafting through the forrest one day, feeling kinda hungry, before stumbling on a cluster of plump reddish berries. He’ll skip around them for a bit, sizing them up and being like, “Hey, berries, awesome.” But that brief moment will probably be ruined by a bunch of YELLOW KRAZEE ANTZ who will come marching over all like, “OH HAI! OMG you guys, I can’t believe we ate an entire pie for BREAKFAST!!!!!1!!!” and the Christmas Island White-eye will roll his eyes, all sarcastic, like, “Oh okay… CRAZY…! Now listen, ants. I’m pretty hungry, and I just found these berries, so would you… umm, hey excuse me, you’re kind of in my way, I was just going to peck there and erm…”
But the ants will all ignore him with their, “Aw shit, I think I just sent a NSFW gif to everyone in the ENTIRE COLONY, LOL!!!!!!1!”
“OMG I totally almost opened that in front of the QUEEN!!! LOLOLOL!!!!!1!!”
At which point the poor Christmas Island White-eye will crossly cut them off with a, “SHUT UP! Just shut up! No one cares! I just want to eat the… Jesus Christ, get the hell off me, you shits!! OFF! Okay fine. You know what? I’m done. You can have the berries. Have ALL the berries you want, I’m getting the fuck out.” And with that, he’ll shake the remaining YELLOW KRAZEE ANTZ out of his feathers and fly off, hungry and pissed.
Then the Christmas Island White-eye will run into a group of red crabs making their annual migration from the forrest to the shore, and one of them will call out to him like, “Hey, Mister White-eye! How’s the family?” And Christmas Island White-eye will tell him about how one of his chicks, Jessica, is hell-bent on leaving the nest before her wings are ready, and Red Crab will sigh good-naturedly and declare, “Fledglings,” at which Christmas Island white-eye will nod with a, “Bless ’em. So how’s the migration going?”
But before Red Crab even has a chance to respond, an army of YELLOW KRAZEE ANTZ will turn up and start crawling up on top of the both of them, all like, “Oh HAI guys! Guess what??!! We accidentally slept in this morning, so we’re doing an expedition… in our PYJAMAS!!!!!!1!!! LOL!” And Christmas Island White-eye will be like, “Well I know where this is going…”, and shake a handful of those tiny yellow menaces out of his feathers before getting the hell out of there. But Red Crab will hesitate nervously, and as a trail of YELLOW KRAZEE ANTZ parade across his claws, he’ll be like, “Umm look. I’m just trying to migrate to the shore over there with a few hundred of my relatives, and we’d really appreciate it if you’d just leave us alone, okay?”
But the YELLOW KRAZEE ANTZ are having none of it, being like, “Whatever man, we’re going to eat your insides!!”
“Haha! ACID IN THE FACE!! AIM HIGHER, HIS EYES ARE ON STALKS!!!”
And having finally dismantled said crabby insides, this supercolony of arseholes will take all the pieces back to their nest for lunch, after which they’ll probably build something not unlike THIS.
* Figure 1 from original paper. (a) Artificial fruiting display with model fruits, (b) red model fruits (scale bar, 1 mm) handled by the thrush ((c) left fruit; credit: Kee Seng Foo) or white-eye ((d) right fruit; credit: Tony Patisser).