Planet Earth II – ‘Deserts’

planetearthiidesertsCONTAINS SPOILERS

Episode 4 was on ‘Deserts’.

Deserts are very harsh environments. The lack of trees means no protection from the elements. There is very little food or water. Deserts have intense heat and are prone to sand storms. We can see the sheer scale of the oldest desert in the world, Namib in Africa, when the programme shows it from a distance, it is jawdropping how wide an area it covers and how tiny lions in there look compared to it.

The lions there are a pride who have had to walk 100 miles for 3 days without food. They go after a giraffe. Normally they wouldn’t even attempt it, as giraffes are much bigger than them, so are difficult to bring down even with a lot of lions against one giraffe. Despite the giraffe being prey and the lions being predators, in a fight it is not always the giraffe that ends up losing its life. Giraffes have a kick powerful enough to kill lions, which is another reason lions rarely try to get one. This pride is desperate though. They try and chase the giraffe towards the chief lioness, who is waiting for it. She launches at the giraffe, but fails to get it, falls thud on the floor and is trampled over by the giraffe as it gets away.

The sand dunes of Namib have a fog which rises at dawn, and will go hours after the sun rises. Darkling beetles come underground to the top of sand dunes, which for them are the size of mountains, and climb to the top. The fog condenses to water on the beetles, and they drink it. Web footed geckos do this too. It is quite funny seeing the geckos licking all over their face, including their eyes. Then, all of a sudden, a couple of the darkling beetles are caught by a sticky tongue and munched by its owner, a namaqua chameleon, who are well aware the beetles come out on foggy days. After all that, the beetles become a meal.

Harris hawks hunt in packs, unlike other birds of prey. We see some hunting for ground squirrels. They all swoop down to try and get a ground squirrel. It hides beneath some cacti, so the hawks continue hunting on foot, surrounding the area and searching for the squirrel. The sight of the hawks hunting on foot reminded me a bit of the velociraptors in Jurrassic Park. I used to always be baffled by the fact that dinosaurs evolved into birds, but I’m increasingly seeing the link now.

One of the most macabre, horrific sights in this whole series was of lizard corpses impaled on cactus spikes. This was because of a butcherbird. When they catch their prey, they impale it on plants and have it as a sort of larder. I was familiar with butcherbirds from an episode of The Animals of Farthing Wood where some newborn baby mice were impaled on a tree by a butcherbird in this way.

In the American West, there are deserts which see ten months of drought, then in one hour millions of tonnes of water falls from the sky as rain. Cati are unique to American deserts. Water is stored to the point where the stem is swollen, and it is protected by spikes. This gives them a distinct advantage over competing plants, so cacti dominate these deserts.

The smell of new grass attracts plagues of locusts in Madagascar. Locusts are actually solitary creatures most of the time, but come together when they sense a plentiful food source. They march along the ground, then if food is plentiful they can reach adult stage three times as fast, shed their skin and become winged adults. We then see billions of them filling the sky. They eat until all the food supply has gone, then they start to die out.

Zebras in the Kalahari also travel towards food from their sense of smell. They can smell the scent of rain, and follow the scent of it during the dry season where food and water is scarce.

There is the saying that “elephants never forget”, and it is true that elephants have good memories. The older females lead the herd to waterholes they remember, some of which they might not haven’t visited for decades.

Sandgrouse chicks are protected from the heat of the sun by their mothers, while their fathers fly in flocks miles away to the nearest waterholes. They soak the water for the chicks up like a sponge with their breast feathers! They are a risk from being eaten by
goshawk, which is why the sandgrouse make sure not to nest near waterholes in the first place, but it still a risk they have to take to get water for the chicks. The fathers then have to make the return journey, now carrying the heavy weight of the water.

Waterholes a few, far between and don’t last long. They attract animals from miles around, everything from zebras, wildebeest, ostrich, elephants, they all need water, so waterholes are soon drained.

Mustang, wild horses, are found in the Western US, and this scene does look a bit like a Wild West movie in some ways. With stallions, waterholes show status. If a stallion controls a territory which has a waterhole, he will be able to mate with mares. There’s one here, as well as an incoming stallion with his own herd of mares. His waterhole has long since dried up, so they have to move and find a new one. The fact that there’s already a herd occupying this one means there is a fight. If the stallion can’t provide for the mares, they will leave him for one who can, so if this incoming stallion loses, his mares will join the herd here and he will have to leave on his own.

The fight between the stallions has a lot of biting and kicking, but victory seems to be decided just because one stallion was able to dodge a kick! It was the new arrival, so he has won the waterhole and the right to mate with the mares he came with and the mares already here.

While the stakes are high, it isn’t a fight to the death. It’s possibly an example of something Charles Darwin noted, that the rules of attraction and reproduction are different from the rules of survival. If the stallions allow themselves to get too injured, breaking a leg or a jaw for example, that’s them doomed to a slow, painful death. They are better off conceding defeat and losing status or a chance to pass on their genes.

Slot canyons in strange shapes are formed by floods carrying sand in gravel carving through solid rock.  Desert rock is also carved in peculiar shapes, in this case because of sandstorms and the heat of the sun. We see huge rocks seemingly resting on smaller ones, and tiny rocks which look close to topelling over the edge, and shapes looking like an exploded muffin.

In the Negev desert in Israel there is Otonyvteris, the desert long-eared bat. It’s unusual among bats, who mostly eat insects and mostly eat while in the air. The desert long-eared bat hunts on the ground, and it eats scorpions! We see a desert long-eared bat after a death stalker scorpion. Both are blind in the dark, but the scorpion can sense the bat from vibrations in the sand. The bat can only hear the scorpion. The scorpion has deadly venom which can kill humans, but the bats are at least partly immune to it, and are also the much bigger creature of the two. This time, the bat gets the scorpion.

I liked the brief but astonishing footage of a lightning storm. It looked almost horror movie-like, with the electricity cracking the dark clouds like a shattering mirror.

‘Deserts’ was after ‘Jungles’, which is definitely from one extreme to the other in terms of environment, only underwater would be more different from a desert. While jungles are getting smaller, deserts are expanding. Deserts already cover a third of the Earth’s surface. Global warming is having a massive effect. Deserts are covering a wider area, getting hotter and drier, and the rate of these changes is getting faster than ever before. There is no doubt this will change how easy it will be to live in them.

‘Deserts’ was almost horror movie like in places. They are one of the toughest natural environments, which made it one of the darker episodes in tone. It wasn’t entirely like that. Bat vs. Scorpion is pretty cool. But the episode was definitely sobering that deserts could end up covering more of the Earth’s surface than they already do. After all, the planet in our solar system which has the most similarities to Earth in terms of climate is Mars. It has much larger deserts than Earth. Venus is almost the same size as Earth and on Venus the greenhouse effect became so intense it ended up evaporating away all its oceans. If cirumstances had been different, Earth might have ended up developing the way Venus and Mars did. It’s debatable what will happen in times to come, but it’s certainly not impossible that most of Earth’s land surface will be desert in the future.

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