Space & habitat use of the African elephant in the Tarangire-Manyara ecosystem
 – a summary

Introduction

After exessive hunting, poor managment & rapidly developing urban areas (human population growth, immigration & landtransformation from natural habitats to cultivated land), species world wide are on the merge of becoming extinct, or they are becoming rarer and rarer. Africa may be one of the worst managed continents, mainly due to trophy hunting, hunting for fine furs & tusks, & nowdays a high pressure on protected areas & natural habitats. Today, this great continent is the home of numerous endangered species, and all the African countries have a special duty to sustain theses species. At the same time as the countries themselves need to develop and be sustainable for its people.

One of the major challenges concerning a sustainable biodiversity & wildlife management in Africa is the problem of the large, widely roaming mammals – elephants being a good example of such.

The most recent estimates regarding total number of elephants in Tanzania, assumes it to be 109.000 animals. Out of these, 1.997-2.334 individs (numbers change from year to year) occupy the area of Tangerie National Park (TNP) in the dry season, and a slightly lower number – 1.386-1.631 animals – occupy the same area during the wet season. The last decades, several traditional migration routes have been disturbed by human activity, but there are still some left – mainly within parkborders and/or Game Controlled Areas (GCA). In GCAs, all human activity but safaries & controlled hunting for tourists is illegal. Only the government is allowed to trade with tusks, but there is a certain permisson for exporting tusks as hunting trophies. In 2003 the government notified the CITES of a doubling in this export quota, now 200 tusks (= 100 animals) per year.

The survey & the park

In the period streching from November 1997-June 2000 there was a research done in Tangerie National Park (TNP) & its adjecent areas in Tanzania by Universita dell’Insurbia & Instituta Oikos (Italy), concerning the space & habitat use of the African elephant in the Tarangire-Manyara ecosystem, also considering human influence of such. The main aim of the study was to explore migratory movement, space & habitat use & how elephant behaviour and activity change seasonally. It also collected data to:
 (i)investigate the location and the availability of natural habitats of those areas outside the park that are of major importance during the wet season
(ii) determine and map the remaining migration routes still used by elephants
(iii) apply data on elephant space use patterns and migration to suggest conservation strategies for the whole Tarangire–Manyara ecosystem.

The reserach involved GPS-satelite tracking of 7 adult elephant cows, all members of different herds within TNP – Bella & Fraha from the northern parts of the park, Kikoti & Silale from the central parts & Kibonge, Maajabu & Kusini from the south. Through data recieved from the GPS-collars, the scientists could make recordings considering habitat use (what kind of vegetation & landscape that is preferred, which resources that were present, etc.), total home area (total area used by the herd during given periods, e.g. wet or dry season), core area (the area within total home area used the most), migrating routes (traditional routes used to get from home areas of the different seasons), movement (registered as movement of head) & speed (speed of movement forewards, recorded according to day/night, wet/dry season & inside/ outside park boundaries).

The Tarangire-Manyara ecosystem, in which TNP lies, hosts one of the largest population of Loxodanta africana africana – African savannah elephant – in Tanzania. The studyarea lies within the eastern limb of the East African Rift Valley, extends over 35 000km2 including TNP & a buffer zone. It is mainly a plateau, altitude 1200m. Vegetation ranges from open savannah to closed forest with all ranges inbetween; Closed Forest, Open to Very Open Forest, Savannah (with or without trees), Closed & Open Shrublands, Temporarily Flooded Vegetation, Permanently Flooded Vegetation, Waterbodies, plus Urban Areas (including rural villages), large-scale Intensive Agriculture Land, small-scale Hebasceous Crops & Fields, Forest Plantations & Tree Crops. Its rich soil makes it ideal for agriculture & forestry.

The Tarangire river acts as a perennial water body, consentrating animals – not only elephants – during the dry season. In the wet season, there are other available waterbodies, and it is a wider spread of the animals. Leaving the park during this period in a search for richer supplies, the animals live of the resources found in a area where there are farmers and areas with a growing demand from the farmers to turn the savannah into large-scale agriculture area. This migration is often the cause of the  Human-Elephant Conflicts (HEC).

Results

The most important results they got from this reaserch, was the indication that there were two major clans within the park; a southern & a central-northern. These two had to be regarded separately, as the individual clans showed no interaction. Further on, the clans were divided into herds, whom had little or no contact other than during migration & mating. This excact point differed slightly betweent he two clans – as the southern clan has no access to perennial water, they tend to clump up a bit during the dry season, than does the central-northern. All three cows from the south showed a high correlation on home areas and traits, whereas the different herds of the central northern showed little or none of such. In the incidents where the latter mentioned did, however, the different herds occupied the same area at different times.

Another important point, was that the southern clan tended to have a more ‘proper’ migration, than what the northern had. With migrations more than 100km south-east to the park during the dry season, keeping away from agricultured land, but still in human influenced area. Among the northern herds, one of them – Bella – periodically went north to the northern sections of Lolkisale GCA, but never more than 20km; hence it cannot really be considered as migration. The remaining northern clan kept most of the time within park borders.

Other important differences between the two clans, would be the area demand. The animals in the southern section had home range areas from 2.002-7.648km2 during the wet period & 977-1.531km2 in the dry season. For the norhtern & central animals, 477-1.078km2 in wet season to 126-332km2 in dry season. This gives a 3-10 times larger home range for the southern than the northern individuals.

Regarding speed, it was recorded that within park borders, the elephant moved faster during day time than night time, this indicating that elephants are day active animals. But outside the park boundries, a change in this behaviour was recorded. Not only did the animals slow down during day time, they also put up the pace during night time, becoming somewhat of a nocturnal animal. It is assumed that they spent the days hiding in closed vegetation, obviolsy disturbed by human activity.

The last point one may assume from the research results, is that elephants do make consious choices regarding what kind of  vegetation they thrive in. There are clear differences between seasons and between home area and migration route. In home areas, elephants more or less avoid closed forests, savannahs (with or without trees) & non-permanent flooded areas, whereas open forests, closed & open shrublands are favourite habitats. While migrating, the same three are still the top favourite ones, but shrublands to a less extent & open forest even more than in home lands. Elephants move more in closed forests, on savannahs & in temporarly flooded areas while migrating, than they would otherwise. These results implies that these large animals seek more shelter while moving than when in their home lands or core areas.

Discussion, my own considerations

It is difficult to make any conclusions from only one study in a very limited area. But, there are other surveys having similar results as the discussed one. The main similarity is the recorded disturbance humans have on elephant activity. It is, however, not in all areas that the elephants are as ‘nice’ as they seem to be in this study. It is a huge problem for farmers all over the African continent were elephants are present, that their crops are raided, that villages are destroyed during the elephants’ search for food & water, and that elephants occationally appear rather aggressivly towards man.

These problemes emphasise even better the need for separating human and elephant interests, to maintain old migration routes for the elephants to use and make them into Game Controlled Areas, and last but not the least to find alternative traits for the people living with these enourmous creatures allowing them to sustain them selves.

The varoius governments of affected countries need to be consequent in dividing areas traditionally not elephant area into agriculture land and urban areas, leaving space for buffer-zones and migration routes.

During a study in northwestern Zimbawe, Richard E. Horare & Johan T. Du Toit investigated the coexistience between humans & elephants on African savannahs (http://www.urban.uiuc.edu/courses/up205/Sp05/AD3group2.pdf). The study showed that there is a negative correlation between human density and elephant density. Although not completly linear, there was a certain threshold of human density, above which elephant density equaled zero. This issue have been given little consideration for study, but might hold the key for a sustainable human/elephant coexistance.

It is an obligation the Afraican countries have to the world, but it should not be the lone responsability of these already economically challenged countries. It is therefore important with initiatives, such as that of former American president George Bush’s government, whom in the late 80s banned all trade with ivory (a major blast for ivory trade, as US at the time held more than 60% of all carved ivory) and implemented the African Elephant Conservation Act (http://www.fws.gov/international/laws/aeca_fv.html). Yearly, U.S. Fish & Wildlife Service distributes a nice sum to chosen projects working for the conservation of the elephant. This is but only one of many examples.

The African elephant once roamed free over most of the African continent, from the Mediterranian coast to the southern tip. Although it is diffucult to estimate numbers, it is considered as good Latin to say that it was somewhere between 3-5millions in the 1930s. During the 60s & 70s, intensive hunting for trophies & tusks, the numbers fell dramatically. This hunt was banned in the 80s. Nowadays, HEC, hunting for bush meat and other poaching is the greatest threath to the elephant population. It is estimated that there are about 400-660.000 wild living African elephants left on the continent. These are all south of Sahara, and very scattered. It is quite obvious that the survival of the elephants depends on humans; wether we will control our hunger for new land & wildlife products.

The African elephant is considered to be a ‘key stone specie’, that is one that plays a major role in the ecosystem. Many scientists believe that the ecology integrety of African savannah & forest to a large extent depends on these animals, and believe that if they disappear, a cascade of environlemtal changes yet poorly understood will occure.

 

By Haldis Kismul