The role of wetlands in wildlife migration in the Tarangire ecosystem, Tanzania

Abstract

Twenty-two years of rainfall data from six sites, 5 years of animal migration data and 2 years of water quality at 13 sites were explored to quantify the role of water in the Tarangire ecosystem. Inter-annual fluctuations in rainfall were large and not predictable solely from the Southern Oscillation Index. Seasonal fluctuations of rainfall were pronounced, with marked wet and dry seasons. In the dry season, the only drinking water available for wildlife was the Tarangire River and a number of small, scattered wetland-fringed water holes. Their salinity was often high (>8 ppt) and was higher in dry years than in wet years, as well as at the start of the wet season. Water quantity and quality may control the annual migration of wildebeest, zebra, elephants and buffaloes. These animals aggregate in the dry season in areas with the least salty water. The timing of seasonal variations in rainfall is largely predictable and controls annual migration. All wildebeest and most zebras migrated out of Tarangire National Park and into the wider Tarangire ecosystem at the start of the wet season, and they returned into the park in the dry season. Some elephants and buffaloes also migrated in out of the park and a larger resident population remained, whose size may vary inter-annually depending on surface water quantity and quality. The extent of the migration zone may also vary inter-annually.

Identifying transit corridors for elephant using a long time-series

“…The north-central area of the TNP, which showed higher predicted probabilities, included the main permanent water sources and high NDVI values. This area receives the highest monthly precipitation (Gereta et al, 2004) and is characterized by A. tortilis, which is highly nutritious in the dry season (Ludwig et al, 2008). This result is consistent with those of other studies (Chamaillé-Jammes et al, 2007;Loarie et al, 2009;Western, 1975).…”

“…Black cotton soil prevails in the flood plains and dark red sandy clay loam elsewhere (Kahurananga, 1979). The annual average rainfall is 450-650 mm; the higher amounts in the west (Prins and Loth, 1988) and the lower in the east (Gereta et al, 2004). The rainfall pattern is bimodal with short rains occurring from November to December and long rains from February to May.…”

Well-being and conservation: diversity and change in visions of a good life among the Maasai of northern Tanzania

“…Simanjiro District is located within the Tarangire-Manyara region of Tanzania, considered to be one of the most biodiverse grassland ecosystems on the planet (Olson and Dinerstein 1998). Lying east of Tarangire National Park (TNP), the Simanjiro Plains are fertile grasslands that provide critical grazing and calving areas for wildebeest and zebra during the wet season (Gereta et al 2004). Rainfall in Simanjiro averages between 575 to 650 mm per year, and is highly variable both temporally and spatially with drought being a common climatic feature (Prins and Loth 1988).…”

Diatomaceous sediments and environmental change in the Pleistocene Olorgesailie Formation, southern Kenya Rift Valley

“…In these circumstances, spring and river fed wetlands are of greater importance to mammal species and may, therefore, influence the distribution patterns and migration routes of large animals. Gereta and Wolanski (1998) and Gereta et al (2005), for example, have pointed out the importance of water quality and wetland development for animal movements in the Serengeti and Tarangire National Parks (Tanzania).…”