Showing posts with label An Immense World. Show all posts
Showing posts with label An Immense World. Show all posts

Thursday, October 12, 2023

Everyone loves elephants

 Michael - Alternate Thursdays

Useful trunks again

Everyone loves elephants. It’s easy to understand why. They have interesting personalities, the females are excellent mothers, protecting and caring for their calves, and elephants are most entertaining with their wonderful trunks. In fact, those trunks are amazing organs. An elephant has an extraordinary sense of smell, and the trunk is always in motion testing the air for scents. After all, it is a mobile nose.  It's also a sensitive touch organ that can feel its way through foliage and branches. The book I discussed last time, An Immense World by Ed Yong, mentions that elephants easily detect their favorite plants even when obscured in lidded boxes and surrounded by other types of vegetation, and that they can distinguish between humans the way a dog can. More importantly for the elephants, the trunk is used to check members of the herd. One researcher conducted a messy experiment of collecting fresh urine from the muddy ground, and driving ahead of an elephant group. She would then deposit it on the ground some way in front of the group. If the urine was from an elephant of another group, it was ignored; if from an elephant of the group, it was checked and then the group proceeded. But if the sample came from a member of the group behind the sniffer, it caused surprise and much additional checking. So not only did the elephants know who the source was, but also where they expected that individual to be.

"toeing" can indicate listening through the feet

Elephants also have apparently complex communication using infra-sound rumbles that are transmitted through the ground and sensed by their feet. In theory, the waves travelling through the earth could reach the other side of the world! What elephants deduce from these seismic signals is a much harder question, and they aren’t telling at the moment.

They also seem happy to interact with humans, provided they are given space and respect. This is described in the book by the late Laurence Anthony The Elephant Whisperer. There are even some hints in the book that suggest a relationship between Lawrence and his elephants (or between the elephants and their Lawrence) that transcends any form of communication that we can analyze scientifically.

Tree damage in the Chobe National Park

Unfortunately, like most happy stories, there is an intrinsic tension. Elephants require an enormous amount to eat—something like 350 lbs of vegetation every day. They have seven complete sets of teeth, and once those are gone, they starve to death. It must be challenging to be always hungry, and they usually rest during the heat of the day in order to use most of the cooler night for feeding. They have essentially no natural enemies—other than man—and tend to be successful if relatively slow breeders. Left to their own devices, elephant populations grow slowly but surely, with the herds led by their matriarchs wandering over vast areas in search of food. They sense rain and head to those areas for the new growth.

Lovely in the river!

The problem is what happens in drought conditions. The elephants move through the bush devastating it, eating everything they can find. That includes any tree bark that they can reach, and once the tree is ringed, it dies since nutrients can’t reach the leaves. Worse, elephants will break off large branches or push over trees altogether in order to reach a few mouthfuls of leaves that they fancy. And they do this even if there is no shortage of food. It’s a strange behavior, because most animal species (present company excluded) interact with their environments quite well, and certainly don’t go about destroying their future food supply. There isn’t a convincing theory about why they behave this way—and apparently always have. Surely, it’s not a successful evolutionary trait.

Of course, now elephants are severely restricted in their movement. In the seventies there was a horrendous die off of elephants in Kenya. The conservation authorities there believed that given their large and connected conservation areas, leaving the elephants unmanaged was the correct and natural strategy. Unfortunately, drought conditions led to the loss of thousands of elephants who died miserably of starvation and left behind devastation that seriously affected other species such as the black rhino.

In more recent times the relentless demand for ivory, drought, and the restriction of their range has led to a decrease in elephant numbers by about two thirds to below half a million world-wide. And now politics has entered the fray.

Under Ian Khama, Botswana banned trophy hunting and the transport of trophies overseas. His policy has always been that the best way of exploiting Botswana’s superb wildlife resources is through high-end tourism with a relatively small numbers of visitors who support a variety of jobs and do comparatively little harm. That strategy has contributed to Botswana’s success. However, Khama’s successor—President Masisi—sees things differently, and that’s probably not independent of his feud with Khama. He accused Khama of elitism and a lack of concern for small farmers in areas where crops were often attacked by hungry elephants. He was also berated for the loss of hunting revenue to the country. There were mutterings about corruption. Masisi reintroduced trophy hunting, citing the overpopulation of elephants in the country.

It became a huge issue in Botswana with the local people on both sides. While it's true that elephants  aren’t currently endangered in Botswana, it’s unfortunate that the issue is now being argued against the background of personal animosity and party politics.

As for the longer term, elephant populations are decreasing in most African countries and climate change will almost certainly devastate some of their natural feeding ranges.

Enjoy them while you can.

Thursday, September 28, 2023

 Michael - Every other Thursday

For many years I’ve had a (very much layman’s) interest in things like animal perception and consciousness. Maybe this was generated to some extent by my interest in image processing and analysis, which naturally links to the way the human eye works and why it works that way. We are all familiar with the ways in which our brains represent images producing all sorts of changes to what is actually before our eyes. Some of these are almost games, like the apparent 3D vision images called stereograms.  

See the shark? Look closer

Here's a really important one.

Edges?

You notice how the edge of each rectangle has been emphasized in the image so that we can easily see where one rectangle ends and the next starts. Well, no actually. Your brain is doing that. We care about identifying things, and so our inbuilt processing automatically does some edge enhancement to help.

What is really fascinating is speculating on what animals see, what their image processing is, and why. It turns out that there’s a big group of biologists who study these things and publish results in specialist journals. However, one of them is also a talented writer who has written a mind-blowing book for the general reader about how other creatures perceive the world and why. His name is Ed Yong and his book is called An Immense World – How Animal Senses Reveal the Hidden Realms Around Us.

Ed Yong's corgi Typo with copies of the book

If I’ve made the concept sound dry, that’s my fault, not Yong’s. The Times called the book "Extraordinary" and The Guardian said it was "Magnificent". As for me, I can’t put it down. It made its way to the Sunday Times best-seller list so I can’t be alone in that.

To start at the beginning, it’s obvious that all creatures share the same physical universe. But, as Yong puts it, “Earth teams with sights and textures, sounds and vibrations, smells and tastes, electric and magnetic fields. But every animal can only tap into a small fraction of reality’s fullness. Each is enclosed within its own unique sensory bubble, perceiving but a tiny sliver of an immense world.” This sliver is called its umwelt – the creatures perceptual world.

Even this starting point is fascinating, especially when we realize that humans are no different from other species in this constraint. In fact, the human sensory bubble is not intrinsically superior to the others, it is just different as they all are. Again in Yong’s words, “Animals are not just stand-ins for humans or fodder for brain storming sessions. They have worth in themselves. We’ll explore their senses to better understand their lives.”.

For example, we are proud of our excellent colour vision. It used to be almost universally accepted that other animals see the world in black and white. That’s now known to be completely false. Dogs have two base colours – blue and yellow, as opposed to our three – red, green and blue, so their colour spectrum or “rainbow” looks different and less rich than ours. It's two instead of three dimensional. On the other hand, hummingbirds see in the ultraviolet in addition to red, green and blue. So they have a four dimensional colour pallet that may be much more rich and extensive than ours. Bees see ultraviolet too and flowers are much more concerned about attracting their attention than ours. Their pollen areas are often coloured in ultraviolet.

Zebra at night
WE can see stripes but...
Yong’s book is full of interesting deductions backed up with good science. For example, zebra. I recall being told by a safari guide on one bush excursion that zebras have stripes for camouflage – to confuse predators by breaking up their outlines. This was counter intuitive but camouflage often is. However, one of Yong’s colleagues, who studies visual acuity (the measure of how large objects must be in order to be separable visually from another at a given distance) pointed out that this argument can’t be true. At night, and at the distances predators like lions stalk, their sight would not be sharp enough to distinguish the stripes. The zebra would just look grey all over. So we need to think more deeply about those stripes...

We all know that mosquitos smell animals by picking up carbon dioxide. I didn’t know that they could smell through their feet. As a result, when they land on exposed skin, they can pick up a delicious skin smell. But if there is some DEET on the skin, they immediately take off again in the same way that we'd jerk our hand away from a hot object without conscious volition. That is why you have to cover all your skin. A general spray in the air isn’t going to work.

It's the understanding of other creatures that flows from the book that I find the most fascinating. If you wonder about these things as I do, you will be richly rewarded by An Immense World.