Preliminary observations of elephant (Loxodonta africana, Blumenbach) movements and home range in Zakouma National Park, Chad N. M. Dolmia1, C. Calenge2, D. Maillard3* and H. Planton4 1
Direction de Conservation de la Faune et des Aires Prote´ge´es, BP 905, N’Djame´na, Chad and Ecole Nationale du Ge´nie Rural des Eaux et des Foreˆts, BP 44494, 34093 Montpellier Cedex 5, France, 2Laboratoire de Biome´trie et Biologie Evolutive (UMR 5558), CNRS, Univ. Lyon 1, 43 bd 11 nov, 69622 Villeubanne Cedex, France, 3Office National de la Chasse et de la Faune Sauvage, Direction des Etudes et de la Recherche, 95 rue Pierre Flourens, BP 74267, 34098 Montpellier Cedex 5, France and 4CIRAD-EMVT, Campus International de Baillarguet, 34398 Montpellier Cedex 5, France and Chemin des Gandins, 38660 Saint Hilaire du Touvet, France
Abstract We used satellite tracking to monitor the movements of three elephants (Loxodonta africana, Blumenbach) in Zakouma National Park (Chad). We studied the movements of two adult females and one adult male from May 2000 to August 2001. All monitored animals restricted their movements to the eastern part of the park until the beginning of the rainy season in May-June. At this time, the animals began to depart from this area, but large movements really begun in July. All animals moved to areas located at 50 km from the park. An attack of poacher forced one male and one female to return to the park. The disturbed female stayed in the park, while the male moved toward the area used by the undisturbed female. The study of movements after the rainy season was possible only for this female. She returned in the park in mid-September. Her movements were shoter after the rainy season, being the shortest during the hot dry season when she stayed very close to permanent water source. The annual home range size of this female was much larger than those observed in other areas in Africa, maybe because of the great uncertainty of living conditions in the park. Key words: Elephant, home range, Loxodonta africana, movement, satellite tracking, Zakouma National Park
Resume Nous avons suivi par satellite les de´placements de trois e´le´phants (Loxodonta africana, Blumenbach) dans le Parc National de Zakouma, au Tchad. Nous avons e´tudie´ les *Correspondence: E-mail:
[email protected]
594
mouvements de deux femelles adultes et d’un mle adulte entre mai 2000 et aot 2001. Les trois animaux suivis ont limite´ leurs de´placements la partie est du parc jusqu’au de´but de la saison des pluies en mai-juin. C’est alors qu’ils ont commence´ quitter cette zone mais les grands de´placements n’ont re´ellement commence´ qu’en juillet. Tous les animaux sont alle´s dans des zones situe´es 50 km du parc. Une attaque de braconniers a force´ le mle et une des femelles retourner dans le parc. La femelle de´range´e y est reste´e tandis que le mle regagnait la zone occupe´e par l’autre femelle. L’e´tude des de´placements apre`s la saison des pluies ne fut possible que pour cette dernie`re. Elle est retourne´e dans le parc la mi-septembre. Ses de´placements e´taient plus courts apre`s la saison des pluies, les plus courts s’observant pendant la chaude saison se`che, quand elle restait pre`s d’une source d’eau permanente. L’aire parcourue par cette femelle en un an e´tait beaucoup plus grande que celles observe´es dans d’autres re´gions d’Afrique, peut-eˆtre cause de la grande incertitude des conditions de vie dans le parc.
Introduction In most African national parks, elephants (Loxodonta africana, Blumenbach) concentrate around the water points during the dry season and scatter during the rainy season (e.g. Lindeque & Lindeque, 1991). In Zakouma National Park (Chad), the elephants move outside the park during the rainy season. The onset, duration and extent of these large movements are, however, unknown. Inaccessibility due to flooding, insecurity related to poaching and atmospheric turbulence during the rainy season prevent
Ó 2007 The Authors. Journal compilation Ó 2007 Blackwell Publishing Ltd, Afr. J. Ecol., 45, 594–598
Elephant movements and home range
intensive monitoring of elephant movements both on the ground and from the air in this area. Satellite tracking can therefore be considered as an alternative. This technology has been used with success on elephants, for example, in Namibia (Lindeque & Lindeque, 1991), Kenya (Thouless, Hoare & Mulama, 1992), Cameroon (Tchamba et al., 1994; Tchamba, Bauer & de Iongh, 1995) and Botswana (Verlinden & Gavor, 1996). This note presents preliminary
595
results on the spatial behaviour of three elephants monitored in Zakouma from May 2000 to August 2001.
Material and methods Zakouma is a 3000-km2 National Park located in southeast Chad. The climate is of the Soudano-Sahelian type (Aubre´ville, 1950) characterized by a rainy season from
(a)
(b)
(c)
(d)
Fig 1 Movements of the monitored elephants during the rainy season 2000 and 2001 in Zakouma National Park, Chad: (a) bull, (b) female 1, (c) female 2 during the rainy season 2000 and (d) female 2 during the rainy season 2001. The main dates of interest are reported close to the relocations of the elephants. The grey line is the boundary of Zakouma National Park
Ó 2007 The Authors. Journal compilation Ó 2007 Blackwell Publishing Ltd, Afr. J. Ecol., 45, 594–598
596
N. M. Dolmia et al.
May to October and a dry season the remainder of the year. The dry season can be divided into two periods: a cool dry season from November to January and a hot dry season from February to April. The hydrographic network is concentrated in the eastern half of the park. The savanna species composition changes according to a north–south gradient, with Acacia sp. dominating in the north of the park, Combretaceae in the centre and Caesalpiniaceae in the south. In May 2000, two cows (female 1 and female 2) and one bull were captured in the north-eastern part of the park. For the three elephants, the estimated age by dentition (Laws, 1966) was between 35 and 49 years. The two females were leaders of their group. They were both lactating; female 1 had two young and female 2 had one young. The three animals were fitted with VHF/Argos collars of the ST-14 PTT/MOD-600HC type (sold by Telonics, www.telonics. com). Satellites NOAA-14 and NOAA-15 allowed their relocation every other day. Two collars (female 1 and the bull) stopped moving in early September 2000 and were later found in the bush. Female 2 was monitored from May 2000 to August 2001. The geographic coordinates (latitude–longitude) of the animals’ relocations were converted into UTM (Universal Transverse Mercator, zone 33) coordinates using Arcview
(a)
GIS (ESRI, 1996). We estimated the home ranges of the monitored animals for each season using the 95% kernel estimator, with a smoothing parameter (h) computed using the least squares cross-validation method (Worton, 1995). We also estimated the annual home-range size for female 2 using the minimum convex polygon, to allow comparison with former studies. These estimations were carried out using Ranges V software (Kenward & Hodder, 1996).
Results and discussion A movement from the north-east towards the centre of the park was observed for the three elephants at the beginning of the rainy season 2000 (May–June). Large movements actually began at about mid-July for the three animals (Fig. 1). Female 1 moved towards an area 50 km to the north of the park and stayed there until the beginning of September. Female 2 and the bull moved towards an area 50 km to the west of the park. On August 1, we were close to the animals and witnessed an attack on their group by poachers with automatic weapons. In response to this event, all elephants present there suddenly gathered as a single group and went back to the park leaving carcasses here and there on the way. Afterwards, the two animals did not behave similarly. The bull moved to an area 50 km
(b)
N
30 km
(c)
(d)
Fig 2 Kernel home range of female 2: (a) during the rainy season 2000 (95% kernel estimator: 2445 km2), (b) during the cool dry season (226 km2), (c) during the hot dry season (107 km2) and (d) during the rainy season 2001 (1951 km2).The thin lines correspond to the 95% kernel home range and the thick lines correspond to the core areas of the home range (50% kernel estimator). The grey line is the boundary of Zakouma National Park
Ó 2007 The Authors. Journal compilation Ó 2007 Blackwell Publishing Ltd, Afr. J. Ecol., 45, 594–598
Elephant movements and home range
597
Table 1 Estimates of the African elephant home range (minimum convex polygon) in various areas in Africa Locality
Country
Home range (km2)
Reference
Lake Manyara National Park Tarangire Game Ranch Sabi Sand Game Reserve Tsavo (East) National Park Tsavo (West) National Park Tsavo National Park Kruger National Park North Namibia Desert Etosha National Park Waza National Park Zakouma National Park
Tanzania Tanzania South Africa Kenya Kenya Kenya South Africa Namibia Namibia Cameroon Chad
15–52 330
