Wildlife: Fight or Flight

Issue 21

Survival is the central story of the African plains. An animal on another's menu faces a couple of real problems - firstly how to avoid a predator's beady eye and secondly how to evade capture once spotted. Camouflage and hiding under cover are two ways to elude the pre-pounce stare. They work as long as the hider doesn't move or is not stumbled on by chance. Likewise, feeding while the enemy sleeps, and vice versa, will reduce the odds of being spotted, but it's not always possible. Cropping or browsing near a bolt-hole might increase the chances of surviving an encounter, if alertness, reaction speed and the sanctuary are up to scratch. Being part of a large herd grazing open grasslands means many eyes for spotting and keeping track of predators so as to avoid capture. However protracted monitoring is very time consuming, particularly for herbivores, which have to spend much of the day feeding in order to obtain sufficient sustenance. In essence, most creatures have to strike a balance between safety and other needs - sleeping, eating, drinking and breeding. Risks must be taken and predators will be encountered. Survival depends on being forewarned of an attack and taking effective action - namely flight or fight. Forewarning Whenever a group of vulnerable creatures gathers to feed, sentries are posted - often on a hillock, termite mound or rock, or in a tree. Others will periodically interrupt their eating to supplement surveillance. Most species scan in give-nothing-away silence, but meerkat sentinels utter regular peeping sounds to show they're alert. The peace is shattered when a predator is sighted. Many birds emit a high-pitched "seeet" or chirp which, at about 7kHz, can be spatially deceptive and difficult to pinpoint. Mammals are less sneaky. Zebras snort, molerats and hartebeest stamp their feet, bushbabies and reedbuck whistle, wild dogs and kudu bark and baboon let forth a two-phase "wahoo" that echoes through the kopjes and sends the troop scurrying to safety. Some animals are more specific. Brant's whistling rat, for example, uses a single, high-pitched note to indicate an airborne intruder and a series of repeated chirps for ground-hugging snakes. The first call directs colleagues into burrows; the second brings them scuttling out and away from danger. Samango monkeys employ a bark and a sharp hacking "pyow" for similar identifications. Suricates are even smarter - they peep an early warning then lift this to a trilling growl, short for a not-so-dangerous goshawk, long and agitated for a predatory raptor. There are different calls for each type of eagle, becoming more guttural as the talons approach. Alarm calls alert others to the danger. They also inform the intruder that he has been spotted and has therefore lost the chance of an unexpected attack. They can, however, pinpoint an otherwise hidden caller and thus signal his demise. Flight Once a creature is forewarned, escape depends on combinations of surprise, speed, stamina, agility and strategy. In springing a surprise many insects, birds and animals will unnervingly and noisily explode from cover and fly, sprint, pronk or leap to safety. When erupting, several grasshoppers also flash bright colours and crickets emit sharp sounds that further startle and confuse an intruder. Some escapees take cover, some freeze (a Damara dik-dik can stand for ten minutes without twitching), some feign dead and some flatten themselves on the ground to merge into the scenery. For cover, snakes and scorpions wriggle into holes or crevasses; desert lizards dig deep into the sand; wildcats and monkeys take to tree tops; suni and nyala antelope thrust into heavy thickets; sitatunga, frogs and hippo dive into water and bushbabies scurry into tree hollows. Meerkats, foxes, aardvark and warthogs bury themselves in burrows - the latter tail first, tusks thrust to the threshold. Squirrels block tunnel entrances behind them, gerbils and desert frogs keep digging deeper and sideways, while spring hares run the warren and escape through another hole. Plains antelope such as Grant's gazelle and springbok rely foremost on an explosive high-speed sprint to get away from lion and hyaena. Evading cheetah, however, also requires tremendous agility in jinking and timing sudden directional changes a split second before the cat pounces. In contrast tsessebe and hartebeest depend on their ability to sustain a fast gallop over distances long enough to outlast a pack of wild dog intent on running them down. Many animals stampede in a noisy, wildly chaotic manner in order to confuse a predator. Zebra, however, bunch up, the stallions defending the rear with their lashing hooves. The confusion caused by fast-moving shapes and colours, and the clouds of dust driven up, combine to confound an attacker. Fight When confronted, prey fight for their lives. For predators, the consequences of injury from the slashing claws of a civet, the sweep of a pangolin's razor-edged tail, the erect quills of a balled porcupine or the rapier-like horns of a defensive gemsbok could well be too high a price to pay for one meal. Thus lion are very wary of warthogs exploding bullet-like from burrows, the foreleg kick of a giraffe and the belligerent cunning of a wounded buffalo. Like everyone else, they shrewdly avoid the repulsive-smelling sulphuric concoction that is squirted offensively up to 1.5m from a Striped polecat's anal glands. Pangolins, White-naped weasels, ratels, some mongooses, the Whip scorpion and the File snake can also become smelly when provoked. So, in defence, armed aggression works. For sheer discourteous hostility, however, nothing beats the belligerent Honey badger. It attacks the genitals with such ferocity that even leopards are savagely routed. But the lightweight title goes to Mrs Thomson. In eight cases out of ten, this 20kg gazelle will courageously see off a 60kg Spotted hyaena bent on devouring her calf. It's a wonder predators survive.

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