Correction to: Effects of dehorning on population productivity in four Namibia sub‑populations of black rhinoceros (Diceros bicornis bicornis)

European Journal of Wildlife Research - The food habits and behavior of medium and large-sized mammals that visited natural salt-licks in a tropical rainforest of Belum-Temengor Forest Complex,...     

Conservation genetics of the black rhinoceros (Diceros bicornis)

We analysed genetic variation in mitochondrial DNA (mtDNA) control region in the Diceros bicornis minor and D. b. michaelianimals at the Western Plains Zoo, which form part of an international ex-situ breeding program. Six of the nine D. b. minor animals were wild-caught from Zimbabwe during the 1990s, and our study revealed five distinct mtDNA haplotypes, and a haplotype diversity of 0.86 in the colony. Phylogenetic relationships between mtDNA haplotypes analyzed using the neighbor joining method reveal that for the small sample available, D. b. minor and D. b. michaeli are reciprocally monophyletic and represent separate ancestral lineages. Nucleotide divergence between the black and and white rhinoceros(Ceratotherium simum) was 14.0%, and nucleotide divergencebetween the D. b. minor and the D. b. michaeli subspecies was 2.6%. This suggests a divergence time for the two blackrhinoceros subspecies of between 0.93 MY and 1.3 MY.     

Characteristics of black rhinoceros (Diceros bicornis) bedding sites

Black rhino numbers have decreased greatly since the early 1970s, primarily as a result of poaching. A recent strategy to protect rhinos in Kenya has been to establish fenced sanctuaries. This has increased the rhino population and that of other species, but problems have emerged because of limited dispersal and rising animal densities. Unfortunately, how rhino utilize habitat, especially areas called bedding sites, is not well understood. These areas provide shade and may be a critical component of rhino habitat. We measured habitat variables at bedding sites located in bedding plots and compared them with control plots at Sweetwaters Reserve, Kenya. Euclea divinorum was the most common tree in the bedding site comprising 64.3% of the vegetation. Elephant dung was significantly more likely to be found in bedding plots than in control plots which suggests that elephants and rhinos use overlapping habitats. Elephants may be causing damage to the tree species that are important for bedding sites. Resource competition between large herbivores in small reserves is likely to negatively affect the tree species. Black rhino habitat, particularly bedding sites, may be at risk and rhino numbers may decrease.     

Gamete rescue in the African black rhinoceros (Diceros bicornis)

Mortality rates are high among captive African black rhinoceroses (Diceros bicornis), due to increased susceptibility to disease. The ability to rescue genetic material from individuals that die unexpectedly represents a practical approach to assist ex situ conservation efforts. The objectives of the present study were to attempt postmortem oocyte recovery from ovaries of African black rhinoceroses (N = 6) and to test the efficacy of equine protocols for rhinoceros oocyte IVM and IVF using cryopreserved rhinoceros sperm. The interval from ovary removal to oocyte recovery was 25.3 ± 13.9 h (mean ± SD). Ovaries were transported at 4 °C or 22 °C and effects of temperature on postmortem oocyte competence was evaluated. Numbers of oocytes collected per female averaged 15.8 ± 6.9. In total, 95 oocytes were recovered. Of these, 85 were inseminated using homologous sperm and 10 were inseminated using heterologous sperm. Overall, substantial numbers of viable oocytes were retrieved from African black rhinoceros ovaries 1 to 2 days postmortem from ovaries stored at ambient temperature. A proportion of these oocytes matured and underwent penetration and fertilization by heterologous or homologous frozen-thawed rhinoceros sperm. The reproductive competence of postmortem oocytes was further demonstrated by development of a single two-cell embryo. Despite the need for further refinements, gamete rescue in the rhinoceros has promise for producing rhinoceros embryos, as well as testing sperm functions in vitro.     

Vitamin E in captive and wild black rhinoceros (Diceros bicornis)

The mean plasma level of alpha-tocopherol (vitamin E) measured in 31 free-ranging black rhinoceros (Diceros bicornis) was significantly higher (P less than 0.001) than that in 11 captive animals (means +/- SE = 0.77 +/- 0.05 and 0.18 +/- 0.03 micrograms/ml, respectively). Vitamin E status may influence the health of captive black rhinoceros; in particular, it may be linked to hemolytic anemia commonly observed in these animals in captivity.     

Genetic structure of the black rhinoceros (Diceros bicornis) in south-eastern Africa

Despite an on-going struggle to conserve the endangered black rhinoceros (Diceros bicornis) since the 1980s, huge capital investment and several genetic surveys, the level of genetic structure and connectivity among populations in southern Africa is not well understood. Here, we undertake a major population genetic study of black rhinoceros in the Zimbabwe Lowveld, an area inhabited by over half of that country’s original Zambezi descendants plus one large population sourced from the relict KwaZulu stock of South Africa. Using nuclear microsatellite and mitochondrial DNA data, we found much higher levels of genetic diversity in the indigenous Zimbabwean populations, where observed multilocus heterozygosity was 0.54 versus 0.40 in KwaZulu, and maternal haplotype diversity was 0.77 versus 0.03. We show, for the first time, that both gene pools can be differentiated from each other on the basis of nuclear markers. This, along with the discovery of recent gene flow between all Lowveld populations, suggests that Zimbabwean and South African gene pools were prehistorically connected.     

Pregnancy diagnosis in the black rhinoceros (Diceros bicornis) by salivary hormone analysis

Saliva samples collected from 12 black rhinoceroses (Diceros bicornis) were analyzed for 20 alpha-hydroxyprogesterone-like and total estrogen immunoreactivity. Five nonpregnant, two conception, and nine pregnancy intervals were monitored. HPLC co-chromatography of immunoreactive free steroid components in saliva indicated that one of three immunoreactive progestin components eluted with 20 alpha-hydroxypreg-4-en-3-one, whereas the single major estrogen peak eluted with estradiol. Direct radioimmunoassay measurements of ether extracts for these two reproductive hormones in saliva provided accurate and consistent profiles in which pregnancy was detected 13 months prior to parturition, and parturition was predicted by approximately 1 month. Measurement of 20 alpha-hydroxypreg-4-en-3-one was more useful in pregnancy diagnosis, and estradiol measurement was useful as an indicator of impending parturition. © 1996 Wiley-Liss, Inc.     

Mortality and female fecundity in an expanding black rhinoceros (Diceros bicornis minor) population

Identifying factors that affect demographic parameters and how those factors act is vital for understanding population dynamics, especially of endangered species. Moreover, specific ideas in the population dynamics of large herbivores underpin the management of the critically endangered black rhinoceros (Diceros bicornis). We studied an expanding black rhinoceros population since its establishment in 1986 in the Great Fish River Reserve, South Africa, through 2008 when managed removals interrupted natural dynamics. During the study, only 13 animals died, of which nine were subadults. In a linear modelling context, we used information-theoretic methods to evaluate the influence of independent variables expected to affect demographic parameters. For females, age at first reproduction (AFR) increased with abundance, but there was no effect of abundance on adult fecundity as measured by inter-birth intervals (IBIs). We evaluated these results in the theoretical context of population dynamics of large herbivores, in particular, Eberhardt’s proposal of a specific sequence in which demographic parameters first respond to increasing density. Our observations are consistent with Eberhardt’s prediction that immature individuals are impacted before adults, but the relative timing and magnitude of density effects on immature individuals was unclear. Rainfall did not influence AFR or IBIs. Maternal age influenced IBIs but much of the observed variation in IBIs was not accounted for by structural variation. Studies of populations more nearly approaching a stable age distribution and carrying capacity are needed to resolve remaining uncertainties and ambiguities in the life history of the black rhinoceros in particular and megaherbivores in general.     

Circulating plasma alpha-tocopherol following a single injection in a black rhinoceros (Diceros bicornis)

Injectable all rac-alpha-tocopherol, at a dose of 12.4 IU/kg body mass, increased circulating levels of alpha-tocopherol in the black rhinoceros (Bicornis diceros) from 0.18 microgram/ml to 1.47 micrograms/ml within 2 hr. Although the plasma level peaked at Day one (13.07 micrograms/ml) and dropped rapidly, substantial residual effects were seen even 10 days (1.50 micrograms/ml) following a single injection. It appears that parenteral vitamin E administration may be suitable for therapeutic treatment of vitamin E deficiency in the black rhinoceros.     

Genetic variation and population structure in remnant populations of black rhinoceros, Diceros bicornis, in Africa

Black rhinoceros (Diceros bicornis) are one of the most endangered mammal species in Africa, with a population decline of more than 96% by the end of the last century. Habitat destruction and encroachment has resulted in fragmentation of the remaining populations. To assist in conservation management, baseline information is provided here on relative genetic diversity and population differentiation among the four remaining recognized subspecies. Using microsatellite data from nine loci and 121 black rhinoceros individuals, and comparing the results with those of other African species affected in similar ways, Diceros bicornis michaeli retained the most genetic diversity (heterozygosity 0.675) compared with Diceros bicornis minor (0.459) and Diceros bicornis bicornis (0.505), suggesting that the duration of the known bottlenecks in these populations has only had a limited impact on diversity. Comparable and moderate degrees of population differentiation were found between D. b. minor, D. b. bicornis and D. b. michaeli. Results from the single sample available of the most endangered subspecies, Diceros bicornis longipes, showed the least diversity of all individuals examined. This information should assist conservation management decisions, especially those affecting population viability assessments and selection of individuals for translocations, and will also facilitate subspecies identification for ex situ individuals of uncertain origin.     

Haematological studies on wild black rhinoceros (Diceros bicornis)-evidence of an unstable haemoglobin

Baseline haematological data were obtained through routine analyses of blood samples from 31 wild black rhinoceroses captured in the Mana Pools National Park, Zimbabwe. Additional tests showed that the haemoglobin of this population is unstable; this observation helps explain the attacks of acute intravascular haemolysis documented in captive animals.     

Predicting the habitat usage of African black rhinoceros (Diceros bicornis) using random forest models

Species distribution models are often used in ecology to ascertain relationships between environmental variables and species presence. Modelling to understand this relationship can be used to aid conservation management strategies. In this paper, we applied the random forest classification method to predict habitat used by black rhino for browsing. The random forest model was created using detailed habitat data collected from Ol Pejeta Conservancy in Kenya. Variables from plots where rhino had been present were compared to those not used by rhino. Independent data were used to test the predictive accuracy of the rules generated. The model performed well with the independent test data, correctly classifying 69% of the sampling plots where black rhino were present. Important habitat features that affected rhino presence were browse availability and density of vegetation, with Vachellia drepanolobium (formerly Acacia) and Euclea divinorum being important components. The analysis also highlighted areas of potential high browse pressure, which should be the focus of continued monitoring and management.     

A note on eyelashes in an Arfican black rhinoceros, Diceros bicornis

The presence of eyelashes on the lower eyelid of an adult Diceros bicornis (L.) was observed and recorded by photography.