The elephant population in Kruger National Park, Republic of South Africa, is growing rapidly. To prevent damage to the Park's ecosystems, the management has culled about 7% of the population annually. Such culls are very controversial. At first glance, contraceptives seem an attractive alternative means of control. We examine contraception as a management option, review the relevant aspects of elephant reproduction, physiology and demography and conclude that this optimism is probably misplaced. First, contraceptives have a wide range of physiological and behavioural side-effects that may prove to be damaging to the individual female and those around her. Second, the elephants in the Park have near-maximal growth rates with inter-calving intervals of less than four years. To achieve zero population growth, about three-quarters of the adult female elephants would need to be on contraceptives. There are no simple alternatives. The smallest numerical target for controlling population numbers is to kill or sterilize females about to become pregnant for the first time. Such a solution is unlikely to appease those who consider killing elephants to be unethical. It may, however, be the one closest to the natural patterns of elephant mortality.

Genetic variation was measured in 105 African buffalo from four populations in South Africa to investigate the effects of habitat fragmentation. Levels of heterozygosity, allelic diversity and genetic differentiation among populations were quantified using seven polymorphic microsatellite markers. There was a significant correlation between the amount of genetic variation and population size, and differentiation was detected among all populations measured by FST and RST. We used likelihood analysis to infer the effective population sizes of each population and to determine whether the fragmented populations were historically differentiated from one another. The genetic estimates of census size were consistent with historical records, and no historical genetic differentiation could be inferred in the original population before fragmentation. These results are discussed in the light of conservation management of fragmented buffalo populations, particularly where natural gene flow is no longer possible.

Thirty-eight captive-born suni (Neotragus moschatus) had chromosomal complements of 2n = 52–56 (fn = 60). Variation in diploid number was the result of two centric fusion polymorphisms: a 4;19 fusion and a putative 18;22 fusion. Specimens that were descendants of wild-caught N. m. akeleyi and N. m. zuluensis were 2n = 52 and 56, respectively, but 2n = 53, 54, and 55 cytotypes were probably the result of hybridization in captivity between the two subspecies. Although populations of suni from different geographic regions are phenotypically indistinguishable, cytogenetic differences between N. m. akeleyi and N. m. zuluensis indicate that they should be recognized as distinct management units. Chromosomal variation among our panel of captive-born specimens and evidence of higher perinatal mortality in supposed hybrid cytotypes suggest that these two subspecies be managed as separate populations, particularly with regard to captive breeding, reintroductions, and animal translocations. Insofar as our findings are restricted to the captive population, the cytogenetics of natural populations of suni should be investigated to determine if indeed N. m. akeleyi and N. m. zuluensis have fixed chromosomal differences or if the centric fusion polymorphisms found in captive animals also occur in wild suni.

As the human population increases, wildlife is becoming restricted to protected remnants of ecosystems with boundaries that limit dispersal. The effect on large herbivores generally is an increase in population density. We investigated the relationship between population density and reproduction in white rhinos (Ceratotherium simum) in Matobo National Park, Zimbabwe. Two lines of evidence were examined: (1) a contrast in reproduction between a high-density and a low-density population; and (2) a longitudinal analysis of changes in reproductive parameters of a fenced population as density increased by >200%. As density increased within the fenced area, the rates of population growth and recruitment of calves decreased, and the age at first reproduction for females increased significantly. Females in the low-density population produced their first calves at significantly younger ages than those in the high-density population. Loss of body condition was related to both population density and female reproductive status. Because most African rhinos exist in relatively small reserves, an understanding of the implications of restricted dispersal and increased population density on their demography is critical to their conservation in situ. Managers need to consider trade-offs between enhanced safety from poaching and density-dependent effects on reproduction in developing conservation strategies for rhinos and other rare, large species confined to reserve systems.

Conservation of tropical forests requires an understanding of the seasonal patterns of abundance and distribution of important seed dispersers. In the forests of Central Africa, three species of hornbills in the genus Ceratogymna (Aves: Bucerotidae) provide dispersal for over 50 species of trees and lianas, yet their ecology is poorly known. We present the first empirical evidence for resource tracking and large-scale movements by two of these species, which were previously considered resident. Hornbill numbers and fruit production were estimated over a one-year period in the Dja Reserve, Cameroon. Monthly abundances of C. atrata and C. cylindricus varied four- and 12-fold, respectively, and were predicted by community fruit availability as measured by fruitfall on a 4.3 km trail. In contrast, C. fistulator abundances varied little and were not related to fruit availability. Synchronous population fluctuations in sites 22 km distant were observed for atrata and cylindricus, but not for fistulator. Together, these results indicate that atrata and cylindricus populations track fruit resources via seasonal emigrations, while the fistulator population appears to be relatively sedentary. Comparisons of hornbill densities in primary and secondary forests suggest that they are important dispersers in both habitats, and will likely play larger roles in central African forest regeneration as more vulnerable seed dispersers are removed by hunting. If large seasonal movements of hornbills turn out to be a general phenomenon, effective management of central African forest reserves will require greater emphasis on reserve connectivity and on seasonal and spatial patterns of fruit production.

Mammalian record collection densities and bias attributable to observer survey preferences are assessed for the former Transvaal region of South Africa using a geographic information system (GIS). A method is presented which may be used to distinguish between highly biased and relatively unbiased sampling densities. Small mammal survey records within the region appear to have been collected relatively independently of the road and urban area infrastructure and are not biased towards nature reserves. Large mammal data on the other hand has mostly been collected within existing conservation areas. Although this latter data set would appear to be highly biased, it does accurately reflect the current distributions of larger mammalian taxa, which are presently almost entirely restricted to conservation areas.

One hundred and sixty-one river sites throughout the Thames catchment area were surveyed during the summer of 1995 and a number of habitat features were recorded in order to identify relevant habitat variables for the water vole (Arvicola terrestris; Arvicolidae). In addition, the role of the American mink (Mustela vision; Mustelidae) in determining the present distribution of water voles in the Thames region was investigated. The data were analysed by using generalized linear models (GLM).

Water voles were found in places characterised by low banks, unmodified channels, vegetated bars, submerged vegetation and were tolerant of moderate levels of bank reinforcement. The presence of mink was the most important variable. The results suggest that the American mink is the main factor determining the current distribution of water voles in this area. Restoration and recreation of habitat for water voles are likely to be a powerful tool in the recovery of water vole populations. It is hypothesised that mink control will be necessary only while the water vole population is small; once the population starts to increase both species could co-exist provided that the habitat is suitable.

Sequences from complete mitochondrial cytochrome b genes of 34 tigers support the hypothesis that Sumatran tigers are diagnostically distinct from mainland populations. None of the latter, including Bengals, Siberians, or Indochinese tigers, were found to have fixed diagnostic characters. Phylogenetic analysis of these sequences confirms these results. Within the framework of a phylogenetic species concept, current evidence thus supports the recognition of two distinct taxa, and within the context of this definition they could be ranked at the species level. This paper also documents a previously unrecognized nuclear insert of mitochondrial DNA that includes, minimally, mitochondrial homologues of a control region that lacks the feline mitochondrial repeat sequences, a complete cytochrome b gene, and complete tRNAThr and tRNAsurPro genes. In a phylogenetic analysis of the nuclear cytochrome b-like sequences and various feline mitochondrial sequences, the nuclear insert clusters with lion mitochondrial cytochrome b sequences, which suggests the insert is at least as old as the split between lions and tigers. The results of this study emphasize the importance of doing more to conserve Sumatran tigers. Because they are underrepresented in zoos relative to Bengals and Siberians, an effort should be made to increase captive breeding stocks of Sumatrans. That Sumatrans are a distinct taxonomic entity relative to mainland populations can be used in educational programs to increase conservation efforts within Indonesia.