In farmyards like this, chickens are easy targets for any opportunist determined enough to find its way in. If there's a weak link in the defences, a fox will find it. (PANICKED SQUAWKING) (TREMENDOUS DIN OF SQUAWKING) Foxes are frequently blamed for killing more than they need, but do they really deserve such a bloodthirsty reputation? No. A fox will not waste what it kills, providing it's not disturbed. However, it must act quickly if it's to make the most of such an opportunity. Few realise that foxes bury their surplus food. They're saving it for when times get tough. A vixen will bury carcasses all over her territory. Later she will use her memory and keen sense of smell to find them again and dig them up. The fox is not a wanton killer, but an intelligent opportunist who thinks ahead. Some opportunities are both brief and seasonal. There's an abundant source of food in this cave, but only for a few weeks, and it lies right in its far depths. Down here, it's totally dark, and we can only see what goes on by using infrared cameras. Darkness is not a problem for bats, who navigate by echolocation. For any other animal, getting around down here is a serious challenge. And there's another major obstacle. Droppings produced by the vast assemblage of bats creates an atmosphere thick with ammonia and fungal spores that can be fatal to those that inhale them. This guano accumulating on the floor of the cave sustains more than fungus. There's a living carpet of flesheating beetles and larvae, which together make short work of anything they can get hold of. This is about as hostile an environment as you'll find anywhere on the planet. Yet that doesn't deter an enterprising and unfussy opportunist the skunk. Indeed, skunks seem almost at home here. They even indulge in a little courtship, as can happen when a male blunders into a female in the pitch dark. What is it that tempts them down into this repellent place? The answer is baby bats. At this age, they are unable to fly, and in such a jostling crowd many lose their footholds and fall. On the ground, the babies are in great danger. The skunks can see nothing whatever, so the fallen bats may survive, if only they can regain the safety of the rock wall. But so many bats fall that the skunks are likely to blunder into enough to make their visit worthwhile. In the total darkness, the skunks can't be sure which end of the bat is which. So to avoid getting bitten, they roll the bat on the ground to subdue it. It's not just skunks that make the most of this macabre seasonal offering. The touchyfeely racoons are here too. It might just be the place for an opportunist that can see with its hands. Exactly which sense the skunks and racoons use to find the bats in the pitchblack cave, no one really knows. Smell seems unlikely, given the overpowering stench of ammonia. How could a skunk or a racoon possibly hear the distress calls of a single baby bat above the deafening squeaks of several million others? The most likely answer is that they use a combination of touch and luck. Both racoons and skunks must rely on, literally, bumping into the bats.