This time last year, a raid on my tamarillo crop had me pondering on possums.  What spidie sense tells the resident marsupials to gobble up your perfectly-ripe figs and grapes the very night before you plan to harvest them? Are they tri-chromatic mutants like we humans, with gerry-rigged colour vision just good enough to grab a ripe mango before the visually well-endowed parrot gets it first? Or do they sniff out your glorious organic harvest in defiance of their typical mammalian red-green colour blindness?
But this year I’ve been mostly thinking about bats.
I’ve had a bumper crop this year off my quick growing and beautiful tamarillo tree, though not quite the 20 kilos that others brag about. So I’ve not been too miffed to find some of the ripe fruit scattered on the ground, flesh neatly scooped out, or to spot a few gnawed items left dangling on the tree. All the other members in my household are either under ten or Scottish, and consequently I have no human competition for weird fruits of any kind. It would seem churlish not to share with the local critters.
So who are my fellow tamarillo lovers? I suspect the grey-faced flying foxes (Pteropus poliocephalus), the most common “macrobats” in this part of New South Wales. While I haven’t eyeballed a single flying fox at our place, I’ve heard them playing cricket with the toxic fruits of the cocos palms for weeks. Soon after lights out, there’s a sequence of companionable shrieks, rustles and thumps, and the palms start raining seeds onto the roof.
One of the many reasons cocos palms are a dangerous pleasure for flying foxes is that the fallen fruit lures them down where they can be chewed up and spat out by the local dogs. Every morning for the last month or so I’ve found a little piece of installation art on a stump near the cocos palm – a few half-eaten fruit arranged with an eye to the design possibilities of the log’s in-house fungus. I thought this was a convenient possum picnic spot, but I’m wondering if it’s a safe haven for bats who are obviously unaware that our house is guarded not by dogs but by night-blind attack chickens.
Our tamarillo tree (“Matimba”, as our eight year old has named her) is just beneath the hateful-but-expensive-to-remove cocos palm, in a jumble of shade-tolerating subtropical plants – galangal, ginger, bananas, naranjilla. My kind of (sub)urban density.
Flying foxes are opportunists. They don’t just eat eucalyptus nectar, lillypilly fruits and mangrove leaves but take what they can find, and are willing to fly a long way to find it. The closest bat “camps” to our place are in Gordon, Warriewood or Avalon – twenty kilometres or away or more. Having come all that distance for a feed, only a bat-masochist who relishes the guts-ache produced by cocos fruits would turn up its nose at the delightful passionfruit-meets-apricot flavoured snack down below.
Unlike possums with their dud colour vision, megabats seem to be spoiled for choice when it comes to tracking down a ripe tamarillo. When our mammalian common ancestor was hiding in a burrow and sneaking around in the dark to avoid veloceraptors, being able to see all the colours of the rainbow was less critical than decent night-sight. Despite a largely nocturnal existence, fruitbats however have evolved the ability to see not just short wavelength but also medium and long wavelength light – and, like birds, can even see in ultraviolet, perhaps to spot flowers and fruits at dusk, at dawn and in bright moonlight.
So perhaps it’s no surprise that my surviving tamarillos were hiding underneath the banana and the monstera leaves, invisible to fruit bats cruising past above. But flying foxes also have a pretty good sense of smell, so after the mysterious overnight disappearance of my first kiwifruit (and my mulberries, and my persimmons, and my grapes…) I don’t think I’ll chance it.
They may share colour vision with us primates and may even share some of our sexual peccadillos, but unless megabats evolve opposable thumbs and can open my back door, they’re not getting any more of my harvest this year.
