Safety in Numbers
Why do animals swarm and flock, migrate and herd? Why do they form prides, packs and coalitions? What is it that drives us to seek comfort in another’s company? In this blog, we’ll delve into exactly what makes these social groups work, and why they do it
With a larger group size, the most obvious benefit is safety in numbers. Sneaking up on your prey species isn’t as easy if there are hundreds, if not thousands, of keen eyes looking out for you. If one member of a Cape Buffalo herd senses trouble, they will share this information with the rest of their herd, and the threat is more likely to be thwarted. The herd keeps the vulnerable calves in the centre, surrounded by the cows and big bulls, each armed with a set of mean horns and weighing up to 900kg. Especially during the mating season or over long migrations, Cape Buffalo can be seen in herds of around 3,000 members, a truly extraordinary sight.
Cape Buffalo are well known to be a deadly threat to any potential predators and, with this solid formation, this threat just isn’t worth it for anything but the most experienced of lion prides. When you think of big cats, you tend to think of solitary creatures. But lions are the obvious exception, so what drove them to form prides? The usual explanation suggested is that it improves their hunting success. Research, however, showed success actually dropped with numbers of 2 – 4 females, before rising again with bigger numbers – i.e., a single lioness has a pretty good shot going alone. New research shows that lions form prides to rather maintain access to prime territories – such as river confluences – where there is the best hunting.
Like male lions, male cheetahs are cast out of their mum’s territories once they reach sexual maturity. Why? The current males won’t stand for their presence, which now represents a direct threat to their rule. This is also nature’s inbuilt trick to avoid inbreeding, which would have devastating consequences on populations if the males weren’t chased elsewhere. Cheetah litter sizes range from one to a whopping eight cubs, but they all rarely make it to adulthood. With mortality rates as high as 90%, if two brothers are lucky enough to make it, they form a life-long bond known as a coalition. Two are stronger than one as they roam for hundreds of miles in search for a current king to replace and a territory to call their own.
It's no use being a predator if you can’t spot your prey, however. The stark black and white stripes of a ‘dazzle’ of zebras might not seem to blend into their surroundings, but for a long time it was assumed that they, seen on mass as part of a herd, functioned to appear something like the shadows of trees in order to confuse their prey. The latest research shows however, that while the stripes do seem to have evolved for camouflage, it's not for predator prevention. Instead, it seems to be against biting insects like the horsefly, mosquito and tsetse fly who, for some reason, simply do not seem able to land on striped surfaces!
Like zebras, lechwe form large herds. During the arrival of the flood, they can be heard coursing their way south as they splash through the new floodwaters using their range of adaptations suited to a semi-aquatic lifestyle. Like all herding herbivores, more members mean more eyes to spot prey, but it also means a higher chance of your personal survival if a predator does go for you. As animals flee, we see something known as the ‘selfish herd theory’ take place. To test this, scientists in England equipped sheep and herding dogs with GPS backpacks and showed that frightened individuals pressed towards the centre of their flock as a self-defence strategy. So, while a herd appears to be a cohesive, cooperative unit working together in the face of a threat, this behaviour actually emerges from the uncoordinated behaviour of self-serving individuals who try to squeeze into the centre of their flock to protect themselves
One of the most iconic sights on the African savannah has to be its breeding herds of elephants, led by a matriarch and consisting of several related females and their offspring moving together in unison. Like Cape Buffalo, elephants move their most vulnerable little ones into the middle of the herd to protect them from danger. Here in Botswana, prides of lions are famous for tackling and taking down even sub-adult elephants, in a behaviour immortalised in Africa’s Giant Killers, a film by Brad Bestelink, founder of the Natural History Film Unit. Herds usually range from 8 – 100 individuals, and at its head is the matriarch – the oldest and most experienced of all the females. Relying on generations of passed down knowledge, she knows where to lead her family in times of drought and hardship, and her value can never be overstated.
Safety in numbers doesn’t, however, always work out. If you’ve ever been to a heronry, you’ll know it’s a loud, colourful, smelly chaos fully of squabbling, squawking residents. This overwhelming of the senses is an immediate attraction to predators, who take delight in feasting on the eggs and young chicks left alone and vulnerable by their distracted parents. Other suggestions, such as a lack of other suitable nesting sites have been suggested as to why heronries form (this seems plausible, given that here in the Delta, these birds seem to exclusively use isolated water figs surrounded by floodwaters), and that the group-breeding makes it easier for individuals to find food, based on where their comrades are heading. The latest suggestion is that it makes finding your mate easier, which would otherwise be very difficult in this big wide world!
When we work as a group, stress levels are reduced, happiness is increased, and ultimately, survival has to go up (otherwise the behaviour would evolve into extinction!) Disruptions to the pride, pack, flock or herd from human interference can have devastating knock-on impacts on the rest of their social units. That is why it is so important that we give animals the protected spaces they need to thrive and survive. Tourism is the economic justification, if ever one was needed, to maintain and grow such areas. So, want to do your bit for conservation? Visit us here in Botswana, and see these incredible animals for yourself. Not so bad, huh?