2012-07-11T17:45:00.001-07:00

Migration and Resource Allocation in Loxodonta africana

Introduction

Each year, multiple times a year, African elephants, or Loxodonta africana, migrate across vast spaces in the continent of Africa. These elephants travel in herds that can be very large in size. The migrations they endure could happen for any number of reasons, including avoiding enemies, climate change, changes in resource availability, or a combination of all of these factors. A null hypothesis to explain these movements could be that the movement is random, and that there is no scientific explanation for why the elephants migrate, and that at any random moment in time, there are an equal number of elephants on the land. One alternative hypothesis is that they are migrating to better allocate resources. Once the resources are depleting where they currently are, they move to a more resource-rich location. Another alternative hypothesis could include that they are straying away from human activity. Human activity is increasing everywhere globally, compromising the habitats and ecosystems of organisms around the world, including African elephants. During my search for information, I researched all of these possibilities.

Materials, Methods, and Study System

I completed a lot of research put in many hours researching this topic. I found that the library proved to be the best place for research due to the quiet, focused environment around me. For my primary resources, I used the Western Michigan University library database systems. I first used the library homepage to search for plausible databases. At the library homepage, I clicked on “Research” and under that heading clicked on the sub-heading of “Subject Guides.” I then clicked on “Biological Sciences.” It then gave me two different databases I could use: Web of Science and Biosis Preview. When using Biosis Preview, I used multiple keyword searches such as “African Elephant,” “Migration Patterns,” and “Distribution,” but I did not find any articles that related to my search topic that would help research my thesis. I then used the Web of Science database. I found many more helpful, related articles here. Because authors were irrelevant to me at the beginning of my search, I used simply key words to find articles related to my thesis. For my first search, I searched for “African Elephant” and “Migration Pattern” and came up with 6 hits, of which I used information from 3. My next search was “African Elephant” and “Migration,” and that turned up 17 articles, 6 of which I could use. My third search turned out to be the one where I found the most information. I searched “African Elephant” and “Resources” and received 91 article hits. Some of them were overlap from previous searches but I found 8 articles that were directly related to my thesis. I found that searching with too many or too refined of key words did not help with finding articles for my thesis because it was too narrow of a search and I was looking to find direct answers for my hypotheses instead of searching for related articles and putting the information together myself. I spent about 6 hours just doing research and reading articles related to my thesis. There were so many articles to choose from and so much to read that I felt I needed to read many of them to acquire adequate knowledge to write my thesis paper.

Results

The null hypothesis stated said that elephant movement is random, and that there is no scientific explanation for why the elephants move from place to place, and that at any random moment in time, there are an equal number of elephants on the land. After researching the two possible alternative hypotheses, I have found an adequate conclusion to the migration of elephants.

Allocation of Resources

One alternative hypothesis stated that elephants migrate to where resources are more readily available than where they currently are. It is no secret that elephants consume mass amounts of water. In such a hot environment, drinking water is one way that the elephants stay cool. In one conducted study, researchers noticed that when they made artificial watering holes around where the elephants migrated, the elephants migrated directly to those spots. When the water would start to run out in that particular area, they migrated to another watering hole (Loarie). The matriarch of the herd is the one who leads and when she started to leave, the rest of the herd would follow suit. In areas of southern Africa, there appears to be two reasons for elephants to migrate for resource allocation. During the wet season, the elephants had smaller home ranges because of the seasonal productivity of the plants. They had smaller home ranges because the seasonal productivity of the plants was limited to a smaller area rather than during the dry season, which is when the home ranges were larger because of the wide distribution of the plants they use for food (Young). The nutrition in the plants is what the elephants are after. Because salt helps with water retention and elephants consume a lot of water, one of the main nutrients that they search for is sodium. This helps to explain the migration patterns of elephants; they follow the plants that are the highest in sodium content (Rode). One common myth and misconception about African elephants is that they cause a lot of destruction wherever they go and destroy the plants. This is not the case because elephants tend to use the same migration routes every year, and they wouldn’t be able to do this if they destroyed the plants. One element that is important in an elephant’s diet is nitrogen. In one conducted study, researchers observed the nutrient content of trees in patches that elephants frequented. They noticed that the elephants tended to “save” the trees that were higher in nitrogen content and the only damaging effects were on the trees that had little to no nutritional value to them. The elephants also use an effect called coppicing of the trees. This happens when the elephants strip the trees of their leaves and nutritional value but don’t kill the tree. The tree then recovers in the following years and the elephants are able to use the new stems from the same trees again (Pretorius). In another study, it was shown that the top five (5) woody plants most eaten by African elephants, all 5 of them showed high coppicing capabilities. In the following years after the coppicing takes place, the elephants return to eat the coppices. This shows how the plant cycles continue to partially dictate when and where the elephants migrate to (Chira). This is not to say that elephants do not impact the vegetation in their environment. The average African elephant eats between 300 and 500 pounds of food per day. In a simple conducted study, with a control site and an experiment site with aloe plants, which is a staple in the diet of elephants, the experiment site had much more damage on the plants than the control site without elephants (Parker). Elephants migrate because their resources are used up at a quicker rate than other organisms who do not eat as much. However this combined with the coppicing technique they use, African elephants are able to use the same migration route year after year because they know that the resources in these areas will be available to them.

Human Interference

Another alternative hypothesis as to why elephants migrate is because of human interference. They are moving to either get away from human activity or human activity has caused them to change their migration routes because the resources they once had are no longer there anymore and new resources are put there instead. In one simple study it was shown how separate populations in the wild and in captivity or a protected area differed. The populations that were protected had flourishing numbers while the populations out in the wild suffered decreasing numbers (Loarie). However, it is impossible to be able to move every elephant to a protected area. But there is something to be learned about their migration patterns, though. Because they use the same migration patterns every year, human interference can be limited because of this knowledge. In one particular study, researchers studied how the social relationships among seven (7) different elephant families influenced their special segregation and seasonal movements. Their data showed that dominant families prefer the same habitats and areas, which, unless humans interfere, would limit their interactions with humans because they use the same migration routes (Wittemyer). One such human interaction that is causing controversy is how the elephants raid the crops of farmers. Their migration routes are interrupted by farms that are being built. In a study that observed crop raiding behavior, results showed that elephants are raiding crops that are high in sodium (Rode). This is actually something the elephants seek out because they need large amounts of sodium in their diet. With this new knowledge of resource location, they alter their migration routes and this increases the amount of human/elephant interference, which is causing a problem because farmers are losing money because of this behavior. This example shows how elephants will change their migration patterns in response to a substation of resources. But they will also change their migration patterns to stray away from human activity. In a study conducted to test stress levels in elephants due to human activity, researchers observed the concentrations of glucocorticoid metabolites in the fecal matter of elephants that lived near Gabon, Africa, where petroleum operations were taking place. The results showed that the elephants living near the oil operations had higher concentrations of glucocorticoid metabolites, which means they had higher stress levels than those living away from the commotion (Munshi-South). The increased amount of human activities is having a negative impact on the populations of African elephants. Elephants will adjust their migration routes, but it is only so long before they do not have anywhere to move to. Researchers have observed that there is a direct correlation between the increase in human population and activity and the decrease of elephant populations. This happens when the amount of land transformed into human-use land, such as for agriculture or housing, becomes much more dominant than the natural habitats of the elephants (Hoare). Human interactions are affecting elephant migrations and allocation of resources in a negative way because the elephants are no longer able to reach the resources they need, so they interfere with humans and their crops.

Discussion and Conclusion

The null hypothesis stated that elephant movement is random, and that there is no scientific explanation for why the elephants migrate, and that at any random moment in time, there are an equal number of elephants on the land. However, after much research, it has been proven that this is not the case. African elephants have migration patterns that they use in relationship to space, time, and resources, and human interactions influence the elephants’ migration and allocation of resources. Human interactions can change an elephant’s migration route due to crops or due to increased industrial activity. It’s not random. African elephants migrate towards their resources in need, and use the same migration patterns because it leads them to the same resources.

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African Elephant Migration