Basic Survival Ecology

Transcription

1 1 Module # 2 - Ecology of Survival Objectives To create an awareness of human vulnerability in the bushveld and to illustrate the value of basic ecology in the survival situation. Expected Outcomes: The learner will be able to:?? Indicate the different levels in a basic food chain?? Describe the difference between biotic and abiotic factors?? Assess his/her position in a given food chain?? Describe outsmarting strategies by providing examples of competition, symbiosis and adaptation. Pre - Test 1) What can you derive from the statement below? A grass stalk was just minding it s own business when suddenly a grasshopper snacked it. Before long a mongoose passes by and gulped down the grasshopper. Later that afternoon an eagle was lucky enough to catch and eat the mongoose. a. The mongoose is a secondary producer b. The grasshopper is a primary consumer c. The eagle is a secondary consumer d. The grass stalk is a carnivore 2) Abiotic factors in the bushveld: a. Are forms of bacteria b. Can be used to cure fevers c. Are most important to survival in the bushveld. d. Can be described as all things living

2 2 Introduction Being eaten is something that can potentially spoil your entire day. It is however the key to a very important energy transfer system in nature. There are various energy transfer systems at work at any given time in an ecosystem of which the most notable are the producers. The producers are the guys that can transform solar energy (Sun energy) into usable energy and complex molecules through the process of photosynthesis. Members of the plant kingdom are the primary producers and they include the green plants, algae and mosses. Shortly on the heels of the producers are the primary consumers or herbivores. These plant eaters have the unlucky job of transforming the plant energy into body mass and protein. They also have the uncanny knack of being very edible themselves at the best of times. This invariably gave rise to very clever and devious ways of convincing predators of the contrary, making it very difficult for the secondary and tertiary consumers to get a decent meal. How would you feel if your food just doesn t want to stand still! Predation is therefore a very advanced and evolved skill and can take hundreds of forms. The simplest and in many cases the most effective form of predation entails being fast, being big and having more and sharper teeth than your food. Being hunted most of the time goes a long way in stimulating clever and creative ploys in averting dinner parties where you are neither host nor guest but invited. It boils down to the fact that not only do you need to take in food and water while surviving but you also have to avoid being food. In a later section we will cover ways to deal with dangerous animals. Since we (humans) are mostly consumers (whether herbivore, omnivore or carnivore) we are going to focus on our position in the bushveld food chain and how it affects our interactions with plants, animals and the elements.

3 3 Our position in the food chain All things living need energy or fuel to sustain their vitality. From the lowest form of life to the most complex or intelligent forms, all biotic (living) forms need to feed. The unfortunate result is that all biotic organisms get energy from somewhere and has to pass it on to something. Getting the energy (feeding) is more fun and much less surprising than passing it on (being eaten). However, this leads to the who-eatswho-in-the-zoo and it s an important aspect of survival. Understanding basic food chains is important because it may improve your current standing in it, for example: Fig 1: A simple food chain Level 1 Level 2 Level 3 Level 4 Level 5 Plant Material Insect Monkey Leopard Bacteria, fungi Producer Primary Consumer Secondary Consumer Tertiary Consumer Decomposer Green plants, algae and mosses, producing complex molecules. Herbivore, vegetarian, plant eater. Omnivore, carnivore, plant, by-products and meat eater. Carnivore, meat only. Scavengers, parasites, carrion eaters, etc. The insect eats the plant, the monkey eats the insect and the leopard eats the monkey. Indirectly the leopard actually got his energy from the original plant material. At any given level some energy is lost due to plants and animals secreting gasses and bodily waste (urine, perspiration, dung). But is it really lost? The answer is no, even dung is consumed by micro-organisms (decomposers) like fungi and bacteria. Scavengers or decomposers will also eat animals that die of old age (although dying of old age is rare in the bushveld). So everything, even dead animals, dead plants and dung is broken down to the simplest elements that they were made out of. The point is that the cycle can then start again, the energy in the simple elements are absorbed by plants and turned into usable energy all over again. At this point it is important to note that all things living do not only eat or absorb living food as it may seem from a food chain but they also take in abiotic (non-living) elements like air, water, minerals and even radiation energy (from the sun). We take abiotic factors for granted, but a factor such as the air we breathe is the most important fuel for our survival, and second to that, water. In fact, without the basic compounds O 2 (Oxygen) and H 2 O (water) all living creatures will perish. About omnivores: Omnivores simply mean an animal that eats plants, animals and by-products of plants and animals. They can therefore be categorised as one or more of the three types of consumer. A human being, not unlike a pig, is essentially an omnivore and can be a tertiary consumer at times and a primary or secondary consumer at other times. Other examples of omnivores are baboons, monkeys, honey badger, civet, lesser bush baby and genet.

4 4 The food chain seems to be a closed system with both biotic and abiotic elements and in that sense it can also be called a nutrient cycle. This brings us to our own (human) position on the food chain. Naturally we would always want to be at the top of the food chain, like the tertiary consumers or predators but the fact of the matter is, in that case we would hardly survive. In order to survive in the bushveld we have to be flexible as to our feeding regime. It is wise to sometimes be the primary consumer (plant eater), especially when meat is hard to come by. Sometimes the opportunity may arise for you to be an omnivore, like the monkey in our example but then you have to be weary of the predators and other dangerous animals as you forage for scraps in the bushveld. Many vegetarians say they will never eat meat or animals but when your life depends on it, it may save your life. It is however your choice and it is quite possible, depending on circumstances, to survive solely on a variety of plants. Why is knowledge of the food chain important for survival? Knowledge of the food chain in which you find yourself can save your life. If you understand how the food chain is constructed and who is in it, you can manipulate it to your advantage. Certain bushveld antelope may be too fast for you to catch but this is not the case with their dung. Rudimentary knowledge of a food chain will indicate to the survivor what plants and what animals are in interaction in the surrounding ecology. Example 1- Scavenger: You and your party (as we have learned in Module # 1) are lost in unfriendly African bushveld. It is November and summer is about to become fully fledged. Because you have rudimentary survival knowledge you know that sour-plums are ripe this time of year. You also know that elephant, kudu (an antelope) and bushbuck abound in the area. Finding their dung is as easy as just keeping your eyes open. You found fresh kudu dung and scraped around in it with a stick revealing a hand full of sour-plum pips. Quite a find because they produce large and tasty nuts! Yes, they stink like hell but just wash them off, the nut inside will not be affected by the animals pungent rumen (stomach) fluid. Elephant dung may also produce edible pips (nuts) of sour-plum, jacket-plum and marula. Baboon dung will also reveal fruits and seeds of edible plants in the vicinity. Humans can generally eat and digest what monkeys and baboons eat. What just happened to you was the following:?? Ecological status: You were a scavenger and also a herbivore (plant eater)?? You obtained nutritional nuts from understanding basic ecology?? You also noticed which other plants in the vicinity have edible fruits (inspecting baboon dung)?? Bonus: Course dung like elephant dung can be used to attract fowl (like pheasants and francolin) to your traps.?? Dry elephant dung is a great anti-mosquito substance when lighted and allowed to glow.?? Dry elephant dung is very good tinder to start a fire with.

5 5 Example 2 Omnivore. Later that afternoon you decide to go foraging. After some time walking you notice that you are surrounded by mopane trees. Not only is this potentially dangerous because a mopane forest can be very deceiving when you navigate (everything looks the same from within a mopane forest!) but it is also an opportunity when you forage. You start noticing many tattered leaves and realise that certain trees have been hard hit by insects. On closer inspection you see who the culprits are. Mopane worms (Gonimbrasia belina)! You immediately collect as many as you can squeezing out their wet intestines between your fingers and pocketing them. Later you will boil them for a while before drying them in the sun. Mopane worms are very rich in protein and in Africa they are considered a staple food, even a delicacy in places. While you were collecting worms you also noticed patchy white markings on some leaves. Then you remember mopane bread! Soon you also collected a handful of bright white mopane bread. The taste is bland but it is nutritious. Mopane bread is in actual fact a scale insect that attaches itself to a leaf and covers itself with layers of a waxy substance. Underneath the hard white scaly shell it goes into rest (just about absorbing itself into a uniform juice ) before it hatches eggs. As you were harvesting you constantly had to sweep tiny insects away from your eyes. If you concentrated in your survival class you would have realised that they are the sting-less mopane bees, famous for the sweetest honey in the bush. Although more difficult to find, a practised eye may see their tiny access tube into the hollow trunk of a tree. Breaking open the nest will reveal a small waxy pot of honey. What just happened to you was the following:?? Ecological Status: Omnivore (Mixed feeding)?? Your knowledge of the tree and its ecology helped you acquire two types of edible insect and honey (a by-product)?? Bonus: Mopane wood is also one of the best for fuelling fires Example 3 Herbivore. On your way back to your hideaway something attracts your attention. You see a cloud of flying insects around a tree and some insect eating birds are also attracted to this tree. You approach and realise it is a buffalo thorn tree. Elated at this sight you and your foraging party run up to it and start looking for buffalo thorn fruits. The fruits are edible and the seeds can be used to make coffee with. You soon realise that there are no fruits in evidence. The insects were attracted to the flowers and the birds to the insects. Everyone turns away saddened, except you who starts picking leaves at a rate. The young leaves, you know for a fact, are edible and can be cooked as spinach. Although the thorns (in pairs along the twigs one curling back sharply and the one pointing straightforward) give you a hard time you collect a whole hat-full for the evening.

6 6 What just happened to you was the following:?? Ecological Status: Herbivore (Plant eater)?? Your curiosity on noticing a food chain in action (flowers-insects-birds) helped you acquire a carbohydrate (green leafs).?? Bonus: Buffalo thorn leafs also have medicinal properties, if chewed and applied to wounds and swellings.?? The thorns can be used to fashion fishhooks Example 4 Producer. Yes you can also be a producer at times and you don t always feed on living material! You noticed certain buck (antelope) licking on stones close to your hideaway. You immediately realised that it must be a salt or mineral lick. Salts and minerals are important because they are used in the formation of complex molecules like in muscle functioning, the building of bones and blood clotting. Important mineral elements are sodium, potassium, phosphorus, chloride and sulphur. What just happened to you was the following:?? Ecological status: Producer?? Knowledge of ecology put you in contact with mineral elements like salts The above examples are just a few of many instances where your knowledge of the ecology can be beneficial to your survival effort. It is, however, important to gain knowledge of specific bushveld plants and animals because not everything is edible and eating the wrong organism may lead to severe discomfort and illness. Outsmarting strategies Outsmarting strategies are aimed at beating your natural enemies to the next meal without yourself becoming a meal. In this regard there is a lot to be learned from the animal and plant kingdom, especially from those members who specialise in being food. Outsmarting strategies for survival has to do with ecological aspects like adaptation, competition and mutualism. Adaptation: Adaptation has to do with changing yourself to increase your chances of survival in a given environment. Impala have adapted smart mechanisms to survive predation from lion, leopard, hyaena, wild dog and cheetah. Just about everything with teeth goes for impala. Predators stalk or move towards their prey every time that they are convinced the prey animal can t see them or are not looking at them. We can learn something from them in this regard. One of their very smart threat detection methods (when one suspects something is wrong) is to stare at the strange object or disturbance for some time. And then nonchalantly continue grazing only to look up suddenly again catching a predator in mid-stalk.

7 7 Certain plants have adapted thorns from earlier stem or leaf forms to protect themselves against animals, especially feeding animals. We can also use branches from such plants to protect ourselves from animals, even from predators like hyaena and lion. Other adaptations: a giraffe s long neck, feeding far above most of the other buck and being able to see predators and other competitors miles away. Elephant s trunk with which they can do a host of functions putting themselves ahead of competitors. The leopard s spots are an adaptation to make it blend into the background in wooded or arboreal environments. A zebra s stripes make them look very blurry if they move past each other in a stampede making it very difficult for a predator to focus on a single zebra. Animals have adapted over millions of years the ability to survive on the bounty of Mother Nature. In a survival emergency you will need to adapt very quickly or face certain demise. You may have to ingest strange plant material or raw meat due to a lack of fire. You may have to drink murky black water dotted with animal dung. Your body has the ability to adapt to this feeding regime, you just have to get your mind around it. At first when eating strange substances your stomach may react towards it (not always). You may have severe diarrhoea, or even signs of mild food poisoning. Get through it because your stomach is busy adapting and getting used to the strange new food and water. Just keep on drinking a lot of potable water to avoid becoming dehydrated and soon enough you would be able to eat and ingest bush food. Competition Competition is an interaction between similar and/or different species of organism in which they compete for the same resource to the benefit of one and the detriment of the other. An example would be hyaenas that will displace a leopard from its kill whenever the opportunity arises. Leopard will rather let their kill go than face possible injury from the powerful jaws of hyaenas. In the same way we can displace animals from their kills due to our strangeness to them and their inherent fear of humans. This is especially effective if you are more in number than the predator species and if you make a huge racket while sticking together. Do not attempt this without expert supervision! As a human you would probably be in competition for food with a host of animals. Baboons are one example, they eat fruits that are also edible to humans, like jackal-berries, raisin-bush berries and marula fruits. If you keep your ears open you can hear where the baboons are congregating because they sometimes make a huge racket. You may find them sitting in a tree competing between each other for the juiciest fruits. Baboons will mostly give way when you enter the tree or their area. Competition as an ecological factor can also be an opportunistic source of food, especially when two organisms of the same species compete for the same scarce resource. You could find two animals locked in deadly battle with each other for a resource, which makes them very easy targets for higher predators, like us humans. Sometimes you find two dead animals in a fatal embrace due to not giving

8 8 in or smothering each other. I once found two dead scorpions stuck in the mouth of a burrow, which they competed for. I ate the one and used the other one as bait with which to catch two fish. Be careful of competition with lions, leopard and other large predators, you can never be sure how they will react and you may pay with your life! Mutualism Mutualism is all about smart alliances between organisms of the same or different species that are beneficial to both parties. One of the most famous alliances in the bushveld is that between the honey-badger and the honey-guide bird. A honey-guide will lead a badger to honey for miles, calling in its familiar Victorrrr, victorrrr! and flying out ahead of it. Eventually they will arrive at the hive and the badger will break it open leaving some of the spoils for the bird as well. There is anecdotal evidence that honey-guides will also lead humans to honey if you care to follow them for an indeterminate distance over possibly dangerous terrain. They will also call out for you and stay ahead by dashing from tree to tree in front of you. Ox-peckers (birds) will sometimes swamp the back and neck of large antelope or bovines like buffalo. They clean the animal of ticks and fleas and in the same instance they get a meal out of it. Other mutualistic relationships are aimed at safety in numbers and as mutual warning systems. This is probably one of the reasons why different species sometimes congregate together, like zebra, blue wildebeest and impala. The one species may be great at detecting stalking predators while the other species provide large numbers of potential prey, making the chances slimmer for any particular individual to be caught. (A quick point between the terms mutualism and symbiosis. Both terms describe a positive interaction between two individuals, either the same or differing species. The difference is that a mutualism is a voluntary interaction, that while beneficial is not paramount to survival for either party. A symbiosis, however is both beneficial and critically necessary. E.g. the relationship that antelope have with their rumen (stomach) micro-organisms. The antelope cannot digest plant material (cellulose) without the aid of these organisms; and the organisms themselves require the unique habitat conditions that an antelopes rumen provides.) Ecology as a discipline is vast and varied but basic knowledge and awareness of ecology in the survival situation may make the difference between life and death in the bushveld. You can find a great deal more about ecology in the Game Ranging Course.