Atlas of Namibia-Its land, water and life
Abstract
An updated Atlas in the same general style as the book produced in 2002.
Online version available at:
www.atlasofnamibia.online
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1. Evolutionary theories of seasonal migration generally assume that the costs of longer migrations are balanced by benefits at the non-breeding destinations.
2. We tested, and rejected, the null hypothesis of equal survival and timing of spring migration for High Arctic breeding sanderling Calidris alba using six and eight winter destinations between 55° N and 25° S, respectively.
3. Annual apparent survival was considerably lower for adult birds wintering in tropical West-Africa (Mauritania: 0.74 and Ghana: 0.75) than in three European sites (0.84, 0.84 and 0.87) and in subtropical Namibia (0.85). Moreover, compared with adults, second calendar-year sanderlings in the tropics, but not in Europe, often refrained from migrating north during the first possible breeding season. During northward migration, tropical-wintering sanderlings occurred at their final staging site in Iceland 5-15 days later than birds wintering further north or south. Namibia-wintering sanderlings tracked with solar geolocators only staged in West-Africa during southward migration.
4. The low annual survival, the later age of first northward migration and the later passage through Iceland during northward migration of tropical-wintering sanderlings, in addition to the skipping of this area during northward but not southward migration by Namibia-wintering sanderlings, all suggest they face issues during the late non-breeding season in West-Africa.
5. Migrating sanderlings defy long distances but may end up in winter areas with poor fitness prospects. We suggest that ecological conditions in tropical West-Africa make the fuelling prior to northward departure problematic.
Significance
Humans are uniquely capable of using cultural innovations to occupy a range of environments, raising the intriguing question of whether historical human migrations have followed familiar habitats or moved relatively independently of them. Beginning ∼5,000 y ago, savannah-dwelling populations of Bantu-speaking peoples swept out of West Central Africa, eventually occupying a vast geographical area. We show that this expansion avoided unfamiliar rainforest habitats by following savannah corridors that emerged from the Congo rainforest, probably from climate change. When Bantu speakers did move into the rainforest, migration rates were delayed by on average 300 y compared with similar movements on the savannah. Despite unmatched abilities to produce innovations culturally, unfamiliar habitats significantly alter the route and pace of human dispersals.
The Khoisan people from Southern Africa maintained ancient lifestyles as hunter-gatherers or pastoralists up to modern times, though little else is known about their early history. Here we infer early demographic histories of modern humans using whole-genome sequences of five Khoisan individuals and one Bantu speaker. Comparison with a 420 K SNP data set from worldwide individuals demonstrates that two of the Khoisan genomes from the Ju/'hoansi population contain exclusive Khoisan ancestry. Coalescent analysis shows that the Khoisan and their ancestors have been the largest populations since their split with the non-Khoisan population ~100-150 kyr ago. In contrast, the ancestors of the non-Khoisan groups, including Bantu-speakers and non-Africans, experienced population declines after the split and lost more than half of their genetic diversity. Paleoclimate records indicate that the precipitation in southern Africa increased ~80-100 kyr ago while west-central Africa became drier. We hypothesize that these climate differences might be related to the divergent-ancient histories among human populations.
Meyburg, B.-U., Mendelsohn, J. M., Ellis, D. H., Smith, D.G., Meyburg, C. & Kemp, A.C. 1995. Year-round movements of a Wahlberg's Eagle Aquila wahlbergi tracked by satellite. Ostrich 66: 135–140.An adult female Wahlberg's Eagle from northern Namibia was tracked by satellite over a total distance of 8816 km and located 104 times between 11 February and 4 November 1994. It migrated on an almost due north heading to northern Cameroon, north-eastern Nigeria and western Chad through the rain forest belt of the Congo and Zaire after the breeding season. The total trans-equatorial distance between the breeding and non-breeding ranges was 3520 km. During the non-breeding season the bird ranged over a large area (ca. 60 000 km') for about six weeks (29 April – 14 June) in these three countries in a rather nomadic pattern covering a minimum distance of 1256 km. During two further months (14 June – 14 August) it restricted its movements to an area of about 5000 km near Maiduguri in the Sudan savannah of north-eastern Nigeria. The return migration took about two weeks longer than that to the north, which took about a month.
An account is given of the satellite tracking of the movements of four adult and three juv. individuals. For the first time a migratory bird was successfully tracked all the way from its breeding grounds in Europe to its wintering quarters in southern Africa and back to Europe. Its outward and return migrations both took about
weeks. Both routes were practically identical, with the bird covering a total distance of 19,400 km, including its movements in its winter quarters in Zambia. On average 166 km were covered per day during migration. Its wintering quarters, where the bird stayed from the end of October until the end of February, extended over an area of ca. 25,000 km2. The autumn migration of all individuals within Africa followed a relatively narrow corridor between longitudes 31° and 36° E from Suez south to Lake Tanganyika from where the birds dispersed. The greatest migration speed was reached by a young bird on the stage from Turkey to the Sudan, flying an average of 289 km per day.
This contribution revolves around the complexities of national belonging among Angolan immigrants in Northern Namibia. In state bureaucracies, people are meant to have just one national identity and they are not encouraged to make any changes therein. For many south-east Angolan people currently resident in Rundu, Namibia, however, such simplicity denies their personal history. They have lived in south-east Angola, western Zambia and northern Namibia amongst people of their own kith and kin, and feel that they have rights and obligations in all three contexts. By taking a diachronic perspective with the case of Angolan immigrants in Rundu, Namibia (1960s–2012), this contribution traces the history of ideas about nationality and the conceptualization of war and peace. It proposes to view these as related to longstanding notions of real and imagined communities, but at the same time as changing in relation to the circumstances and varying according to personal history.
Heavy grazing of communal rangeland appears to be in conflict with the societal aim of conserving biodiversity. Understanding the grazing system in context is essential for intervention. One mixed and one pastoral system along a rainfall gradient on communal lands in Namibia were studied. Data on 224 calves were gathered from the life history data of 81 cows. Body measurements of 80 cattle were recorded. Fifteen households were interviewed regarding their cattle management practices. Age at first calving differed between the two systems, being 32 months in the pastoral and 61 in the mixed system. Calving intervals were shorter and the number of parities higher in the pastoral system (16 c.f. 27 months, and 3.0 c.f. 2.2, respectively). Cows in the mixed system were older (100 c.f. 60 months), and had better body condition. In the pastoral system, male calves were sold and females retained, while in the other, male calves were kept in the herd. In the mixed system, males provided draught power and their grazing resources were primarily threatened by cropland expansion. In the pastoral system, reducing head counts in order to diminish grazing pressure would require incentives and alternative options through changes in societal priorities and policies.
The contention that cattle are held as a store of wealth in Swaziland is supported by a regression analysis of slaughter against price and rainfall, and by an examination of the Swazi herd structure. The failure to recognize that cattle directly satisfy both wealth and income motives in traditional societies has led to the implementation of production-oriented livestock development programs, which may worsen the serious overgrazing problem in Swaziland. Observations elsewhere indicate that there are lessons to be learned for livestock developemnt in other overgrazed parts of eastern and southern Africa. 17 references.