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Abundance, habitat preference and distribution of small mammals in Dinder National Park, Sudan

2007; Wiley; Volume: 46; Issue: 3 Linguagem: Inglês

10.1111/j.1365-2028.2007.00871.x

1365-2028

Ibrahim M. Hashim, Khalda S. Mahgoub,

Wildlife Ecology and Conservation

Few reports were available about the abundance and distribution of ungulates in the Dinder National Park (Hashim, 1984, 1987a; Hashim & Dafala, 1996;Tomor, 2006). The park (Fig. 1) comprises the Dehra, the Riverine and the Maya ecosystems. The Dehra is mainly the hinterland (dehra) that covers most of the park area. The Riverine consists of the Dinder and Galagu rivers and their tributaries, the Maya the numerous mayas (meadows) lying parallel to the Riverine ecosystem. Vegetation in the three ecosystems is classified into grassland, woodland and Riverine forest. Detailed description of the park was given by Mahgoub (2005). Map of Sudan showing location of the Dinder Park Although they comprise an important component of its ecosystems, small mammals were rarely considered in the overall strategic management of Dinder National Park. The objective of this study was to address the small, nocturnal mammals in the families Glagonidae, Nycteridae, Soricidae, Muridae, Herpestidae, Viverridae, Felidae, Canidae, Hystericidae, Hyrocoidae, and Orycteropodidae besides the diurnal Sciuridae. The hypothesis to be tested is that the small mammals are randomly distributed in the park's ecosystems, irrespective of the uncontrolled burning. Our objectives were to identify these mammals, determine their abundance and map their distribution in park. The Dehra, Riverine and Maya ecosystems of Dinder National Park were studied during the dry season from January until May, 2002 and in May, 2005. In each ecosystem, line transects of 500-m length were selected randomly, totaling 66 lines of which 23 were in the Riverine, 40 in Dehra and three in the Maya. Lines in Dehra started either at the maya's edge or at 500-m intervals along the park's roads. In each road, the total lines were selected by measuring its length, using the Global Positioning System (GPS). The number of lines to be sampled was calculated by dividing the road length by 500 m and only 30% of these were selected randomly; line directions being north, south, east or west. In case of mayas, the lines started at their edges and ran towards the dehra in the same directions. Box traps (Mosby, 1955) were set at the predetermined 50-m interval along the lines where animal signs and ground cover were sampled simultaneously. Baits (fish or meat) were placed inside the traps that were checked the next morning. After recording their location in GPS, captured animals were taken in their traps to the campsite. Each animal was put in a plastic drum to which a piece of cotton moistened with ether or chloroform was added. The drum was closed tightly for a few minutes, shaken slightly every now and then to check if the animal was still conscious. When completely anesthetized, the drum was opened, the animal removed quickly, identified and released at the place where it was captured. The ratel and the porcupine were dug out from their burrows. The serval cat was captured by a snare, the shrew collected dead from Galagu River. The slit-faced bat was collected while digging out the porcupine from its burrow, using a piece of cloth. Animal signs (burrows, fecal droppings and diggings) were counted in 30 × 50 m belt transects along the line transects. The night survey which was conducted by a vehicle along the major roads of the park began at 7.00 hours and ended at 12.00 hours. With two persons on its top, the vehicle was driven slowly and the animals were searched along the road, using 400,000 Watt candle spotlight. Once seen, the animal was confused by moving the spotlight up and down while approaching it slowly, so it remained standing still. Many times, the animal was approached closely, identified and its location recorded in GPS. A total of 247 km was covered in the night survey. Respective locations of sightings in the night survey and the trap capture were used for mapping the distribution of the small mammals in the park. The ground cover was assessed by the ten-point frame (Barbour, Burk & Pitts, 1981) at 50-m interval along the lines. The ground cover in the Dehra, Riverine and in Maya is presented in Fig. 2. Litter and burnt area dominated the three ecosystems. Conversely, the burnt area was high in Dehra and relatively low in the Riverine and Maya because they were moist. Generally, 52% of the park's area was burnt in the dry season. The ground cover in Dehra, Riverine and Maya ecosystems of the Dinder National Park Nineteen mammalian species were identified (Table 1) of which 36.9% were seen in the night survey, 52.6% captured and 10.5% indicated by their signs. Ten percent of the total traps set captured animals from the Riverine, 4.3% from Dehra. In the latter ecosystem, 41.3% of the capture was in burnt area, 85.7% in unburned area. In the Riverine, however, 100% of the capture was from the unburned area. Only Viverridae, Felidae, Hystricidae (porcupine) and Orycteropodidae (aardvark) were positively indicated by their signs. The most abundant mammal was the common genet; the least was the fox (Fig. 3). The small mammals were restricted in their distribution to the Dinder River (Fig. 4), mostly occurring at its western side. The occurrence of the small mammals in Dinder National Park in the dry seasons of 2002 and 2005 Burning, which usually starts in November, takes place in Dehra ecosystem but mayas are burnt only when they dry up (Eltom, 1982). The burning was done by nomads, poachers, resource collectors and Wildlife personnel when they opened the roads at the beginning of the dry season. Because they prefer dense, herbaceous vegetation cover, small mammals are likely to be affected by the burning both in the Riverine and the Dehra ecosystems. The area in the middle of the park is a good habitat for the bush baby where large snag trees are prevalent to which the animal retreats during the day. The dispersion of the small mammals in the park seemed to be dictated by the Riverine ecosystem and Wildlife Posts where there were fewer disturbances. In conclusion, the dense vegetation cover in the Riverine and Dehra and few disturbances in the former ecosystem attract the small mammals in Dinder National Park.