Rhino Population Research Articles

Poaching is directly and indirectly driving the decline of South Africa's large population of white rhinos

AbstractLarge herbivores, particularly in water limited systems, are vulnerable to the impacts of poaching (illegal hunting) and human‐induced climate changes. However, we have little understanding of how these processes can reshape their populations. With some rapidly declining populations there is a need to understand the effects of these stressors on populations of vulnerable large herbivores like the white rhino (Ceratotherium simum simum). We developed age‐structured models for the rhino population in Kruger National Park, home to 49% of South Africa’s rhinos. We wanted to determine the relative influence of poaching and climate on the current and future population size and demographics, examine the potential of a dependency effect (the loss of calves from poached females) and quantify the compound effect (loss of future young). Our results indicated that population declines were largely driven by poaching and included a dependency effect. Rainfall had a measurable but smaller influence on rhino populations and had an additive effect; reduced rainfall exacerbated poaching losses. Current poaching levels have resulted in a reduction to the lifetime reproductive output per cow from approximately 6 to 0.7 calves: a compound effect of 5.3 future offspring. Under current levels of poaching, we project a 35% decline in the Kruger rhino population in the next 10 years. However, if poaching intensity is cut in half, we project a doubling of the current population over the same time frame. Overall, our models showed little sensitivity to demographic and environmental parameters, except for adult survival. Our results suggest that maintaining and improving the lifetime reproductive output of rhino cows should thus be the highest management priority and that new management targets should consider both the dependency and compound effects associated with poaching on rhino cows.

Analysis of Blood Biochemistry of Free Ranging and Human-Managed Southern White Rhinoceros (Ceratotherium simum simum) Using the i-STAT Alinity v®.

Handheld point-of-care blood analyzers deliver rapid results for biochemical and hematologic parameters, making them very useful in veterinary clinics and in fieldwork applications. This study compared the biochemical and hematologic parameters generated by the novel point-of-care analyzer i-STAT® Alinity V CHEM8+ cartridge between human-managed and free ranging populations of southern white rhinoceros (Ceratotherium simum simum). In addition, a novel reference interval for ionized calcium (iCa), a parameter of diagnostic and prognostic importance, was established for southern white rhinoceros. Blood samples were obtained from 10 managed (6 at NC Zoo and 4 at Busch Gardens Tampa Bay in 2019) and 30 free ranging white rhinoceros (collected in South Africa between 2018 and 2019) and analyzed using the i-STAT. Multiple parameters were higher (P < 0.05) in free ranging versus managed animals including potassium, blood urea nitrogen, creatinine, glucose, hematocrit, and hemoglobin. Conversely, iCa concentrations were higher (P < 0.05) in the managed populations of white rhinoceros. The RI determined for iCa was 1.36–1.56 mmol/L, with a mean of 1.46 mmol/L, and was determined using the guidelines from the American Society for Veterinary Clinical Pathology. There was no difference in anion gap, chlorine, total carbon dioxide, or sodium between the populations. Seasonality and locality of sampling as well as diet may be contributing factors to the higher iCa concentrations in managed rhinoceros. The six elevated parameters in free ranging rhinoceros are likely attributable to dehydration compounded by capture stress. This data provides insight into the state of several biochemical and hematologic parameters in southern white rhinoceros and will allow veterinarians to better assess the health of both managed and free ranging populations.

SEROLOGICAL EVIDENCE OF COXIELLA BURNETII INFECTION IN THE WHITE RHINOCEROS (CERATOTHERIUM SIMUM) IN SOUTH AFRICA.

Coxiellosis, or Query (Q) fever, a disease caused by the intracellular bacteria Coxiella burnetii, was recently described in a managed breeding herd of white rhinoceros (Ceratotherium simum) in the southeastern United States. Clinical disease often results in abortion and could represent a conservation challenge for this species. In addition to the reproductive and herd management consequences, coxiellosis is also a zoonotic disease. Infection or clinical disease in any free-ranging rhinoceros species in a national park setting has not been previously described. In this study, evidence of prior infection was measured by immunofluorescent antibody titers in 89 serum samples collected from white rhinoceros within private reserves and a national park in South Africa. Total seropositivity was 48/89 (53.9% [95% CI, 43.6-63.9%]). Animals on private reserves had a seropositivity of 21/51 (41.1% [95% CI, 27.1-55.2%]), and national park rhinoceros had a higher rate of seropositivity at 71.0% [95% CI, 55.9-86.2%] (27/38; P= 0.004). Adults had a higher seropositivity compared with subadults (P= 0.03). There was no difference in seropositivity between sexes (P > 0.05). Results demonstrate that South African white rhinoceros populations are exposed to Coxiella, which could result in underrecognized reproductive consequences. Further studies should investigate potential implications for public health and conservation management of this species.

Effect of high population density of eastern black rhinoceros, a mega‐browser, on the quality of its diet

AbstractHigh density of herbivore populations can lead to intense foraging competition and depletion of food consequently lowering diet quality and population performance. We tested for the effects of the density of eastern black rhinoceros (Diceros bicornis michaeli) in ninein situpopulations of 0.01–0.7 individuals per km2density range on the quality of their diet while controlling for plant available moisture and plant available nutrients. We used faecal calcium, phosphorus, copper and zinc concentrations as proxy indices for dietary quality from 473 fresh faecal samples obtained from 77 adult animalsin situ, after determining a positive faeces‐diet mineral correlation in feeding trials with black rhinoceros in zoos. Some populations surpassed 70%–80% of their estimated maximum stocking densities expected to cause impact on forage. However, we did not find significant correlation between rhino population density and dietary quality, as measured via faecal mineral nutrient content. This suggests that black rhinoceros may have sufficient behavioural plasticity to adjust their diet to cover their nutritional requirements when density increases. Instead, 1‐month lagged plant available moisture, reflecting precipitation over the 4 weeks preceding each sampling effort, significantly explained the mineral concentrations in the faeces. By contrast, plant available nutrients had no effect.

Female Southern White Rhinoceros Can Select Mates to Avoid Inbreeding.

Current management models for many endangered species focus primarily on demographic recovery, often ignoring their intrinsic ecological requirements. Across the protected area network of southern Africa, most southern white rhinoceros are managed in populations of less than 50 individuals, experiencing restricted dispersal opportunities, and limited breeding male numbers due to their exclusive home range requirements. In the absence of information on the breeding structure of these populations, poor management decisions may require females to either forego a breeding opportunity or select to inbreed with close relatives. Here, we use a combination of social pedigree data together with genetic analyses to reconstruct the parentage of all 28 offspring produced in a 5-year period in a managed free-ranging southern white rhinoceros population. During this period, all breeding females (founders and first-generation daughters) had access to both a founder male (father to most of the daughters) and two recently introduced inexperienced males. We report that while founder females were more likely to breed with the founder male, their daughters, in contrast, were more likely to breed with the introduced males, thus avoiding inbreeding. However, we also found evidence of father-daughter inbreeding in this population, and contend that in the absence of choice, rather than forego a breeding opportunity, female white rhinoceros will inbreed with their fathers. We argue that to effectively conserve the southern white rhinoceros, managers need to understand the breeding structure of these small populations, particularly in terms of parentage and kinship.

Genomic insights into the conservation status of the world\u2019s last remaining Sumatran rhinoceros populations

Small populations are often exposed to high inbreeding and mutational load that can increase the risk of extinction. The Sumatran rhinoceros was widespread in Southeast Asia, but is now restricted to small and isolated populations on Sumatra and Borneo, and most likely extinct on the Malay Peninsula. Here, we analyse 5 historical and 16 modern genomes from these populations to investigate the genomic consequences of the recent decline, such as increased inbreeding and mutational load. We find that the Malay Peninsula population experienced increased inbreeding shortly before extirpation, which possibly was accompanied by purging. The populations on Sumatra and Borneo instead show low inbreeding, but high mutational load. The currently small population sizes may thus in the near future lead to inbreeding depression. Moreover, we find little evidence for differences in local adaptation among populations, suggesting that future inbreeding depression could potentially be mitigated by assisted gene flow among populations.

Optimisation and application of a forensic microsatellite panel to combat Greater-one horned rhinoceros (Rhinoceros unicornis) poaching in India

The Greater one-horned (GoH) rhinoceros is one of the most charismatic endemic megaherbivores of the Indian subcontinent. Threatened by poaching, habitat loss and disease, the species is found only in small areas of its historical distribution. Increasing demands for rhino horns in chinese traditional medicine has put the existing population under continuing threat, and large profits and low conviction rates make poaching difficult to contain. DNA forensics such as the RhoDIS-Africa program has helped in combating illegal rhino horn trade, but the approach is yet to be optimised for Indian GoH rhinoceros. Here we followed the International Society for Forensic Genetics (ISFG) guidelines to establish a 14 dinucleotide microsatellite panel for Indian GoH rhinoceros DNA profiling. Selected from a large initial pool (n = 34), the microsatellite markers showed high polymorphism, stable peak characteristics, consistent allele calls and produced precise, reproducible genotypes from different types of rhino samples. The panel also showed low genotyping error and produced high statistical power during individual identification (PIDsibs value of 1.2*10−4). As part of the official RhoDIS-India program, we used this panel to match poached rhino carcass with seized contraband as scientific evidence in court procedure. This program now moves to generate detailed allele-frequency maps of all GoH rhinoceros populations in India and Nepal for development of a genetic database and identification of poaching hotspots and trade routes across the subcontinent and beyond.

The complete mitochondrial genome sequence of Oryctes rhinoceros (Coleoptera: Scarabaeidae) based on long-read nanopore sequencing.

BackgroundThe coconut rhinoceros beetle (CRB, Oryctes rhinoceros) is a severe and invasive pest of coconut and other palms throughout Asia and the Pacific. The biocontrol agent, Oryctes rhinoceros nudivirus (OrNV), has successfully suppressed O. rhinoceros populations for decades but new CRB invasions started appearing after 2007. A single-SNP variant within the mitochondrial cox1 gene is used to distinguish the recently-invading CRB-G lineage from other haplotypes, but the lack of mitogenome sequence for this species hinders further development of a molecular toolset for biosecurity and management programmes against CRB. Here we report the complete circular sequence and annotation for CRB mitogenome, generated to support such efforts.MethodsSequencing data were generated using long-read Nanopore technology from genomic DNA isolated from a CRB-G female. The mitogenome was assembled with Flye v.2.5, using the short-read Illumina sequences to remove homopolymers with Pilon, and annotated with MITOS. Independently-generated transcriptome data were used to assess the O. rhinoceros mitogenome annotation and transcription. The aligned sequences of 13 protein-coding genes (PCGs) (with degenerate third codon position) from O. rhinoceros, 13 other Scarabaeidae taxa and two outgroup taxa were used for the phylogenetic reconstruction with the Maximum likelihood (ML) approach in IQ-TREE and Bayesian (BI) approach in MrBayes.ResultsThe complete circular mitogenome of O. rhinoceros is 20,898 bp in length, with a gene content canonical for insects (13 PCGs, two rRNA genes, and 22 tRNA genes), as well as one structural variation (rearrangement of trnQ and trnI) and a long control region (6,204 bp). Transcription was detected across all 37 genes, and interestingly, within three domains in the control region. ML and BI phylogenies had the same topology, correctly grouping O. rhinoceros with one other Dynastinae taxon, and recovering the previously reported relationship among lineages in the Scarabaeidae. In silico PCR-RFLP analysis recovered the correct fragment set that is diagnostic for the CRB-G haplogroup. These results validate the high-quality of the O. rhinoceros mitogenome sequence and annotation.

Patterns in rhino poaching activity on private land in South Africa

AbstractPoaching on private land may potentially significantly deplete the rhino population yet is poorly studied. We focus on temporal patterns in poaching events, whether there is any evidence of targeting of specific categories of rhino (in relation to species, sex and age) and whether these patterns in poaching show any trends over time. Using rhino owner and (mainstream and social) media reports, we complied a database of private land poaching events between 2003 and 2017. Patterns in poaching activity were broadly consistent over time. Poaching is most likely at night, under the full moon, and close to the property perimeter. Whilst there was no consistent temporal pattern in poaching, there was evidence of increased poaching during the weekend (Friday–Sunday) compared to weekdays (Monday–Thursday) in 2017. Prioritising rhino protection efforts at these times may therefore be the most efficient use of limited resources. Because there is no evidence that poachers selectively target rhinos, efforts undertaken by private owners to protect specific individuals or groups may be ineffective. Our research also highlighted key data that were currently not clearly recorded, including collateral calf deaths and lost pregnancies, which may have a significant impact on the scale of the rhino poaching problem.

Ethical leadership is not black and white: a case study on stakeholders and African rhino conservation

Rhinos are a charismatic symbol of Africa's thriving wildlife, but their future is threatened. Rising demand for rhino horn along with inefficiency and corruption in protecting rhinos makes these animals vulnerable. The rhino population is facing a crisis situation with thousands killed illegally for their horns each year. The countries of eSwatini, Botswana, and South Africa are at the forefront of the issue, but little attention has been paid to understanding the positions and viewpoints of the local people. Qualitative interviews were conducted with local ranchers, conservationists, and the general population. Grounded theory techniques were utilised and various stakeholder interviews were conducted to examine the situation from different ethical perspectives. Primary ethical perspectives considered in this case include deontology, consequentialism, and justice/fairness; each perspective is applied to frame the issue with respect to different stakeholder groups that directly influence the rhino crisis.

Examination of population genetics of the Coconut Rhinoceros Beetle (Oryctes rhinoceros) and the incidence of its biocontrol agent (Oryctesrhinoceros nudivirus) in the South Pacific Islands.

Recently, incursions of the Coconut rhinoceros beetle (CRB), Oryctes rhinoceros, have been detected in south Pacific countries that were previously free of the pest. It has been suggested that this range expansion is related to an O. rhinoceros haplotype that is reported to show reduced susceptibility to the well-established classical biocontrol agent, Oryctes rhinoceros nudivirus (OrNV). We investigated O. rhinoceros population genetics and the OrNV status of specimens collected in Fiji, New Caledonia, Papua New Guinea (PNG), Samoa, Solomon Islands, Tonga, Vanuatu and the Philippines. Based on the sequence of the mitochondrial CoxI gene, we found three major mitochondrial haplotype groups (CRB-G, CRB-PNG and CRB-S) across the region. Haplotype diversity varied between and within countries and a high incidence of OrNV infection was detected in all haplotypes wherever they occurred. The O. rhinoceros population in some countries was monotypic and all individuals tested belonged to a single haplotype group. However, in Samoa we detected CRB-S and CRB-PNG and in Solomon Islands we detected all three haplotype groups. Genotyping-by-Sequencing (GBS) showed genetic differentiation in the O. rhinoceros nuclear genome across populations on different islands and provided evidence for gene flow, resulting in a well-mixed population, despite the presence of different CoxI haplotypes in Solomon Islands. Evidence of admixture was also detected on both islands of Samoa. The current CoxI based method is not a reliable diagnostic marker for phenotypic traits, especially in countries such as Solomon Islands where the mitochondrial haplotypes have come back into sympatry and are mixed. To identify possible mechanisms of resistance to OrNV, further molecular analyses O. rhinoceros in response to virus infection is required. To improve biological control of O. rhinoceros, such analyses will need to be combined with an improved understanding of the population genetics of the pest and the evolutionary history of OrNV in the region.

Malignant Snare Traps Threaten an Irreplaceable Megafauna Community

Tropical forests are under severe threat from over-hunting. Subsistence harvests and poaching have decimated wildlife populations to the extent that nearly 50% of Earth’s tropical forests are partially or fully devoid of large mammals. Declines are particularly acute in Southeast Asia where ongoing defaunation, largely attributable to indiscriminate snare trapping, is widespread. Using the extensively forested Aceh province in northern Sumatra as a case study, we document rampant snaring, which threatens Earth’s last sympatric population of tigers, rhinoceros, elephants, and orangutans. To prevent catastrophic hunting-induced impacts already experienced in mainland Southeast Asia, we call for more comprehensive conservation planning assessments that strengthen wildlife law enforcement, promote collaborative anti-poaching, and research species-specific snaring impacts, particularly in the context of human-wildlife conflict. We conclude with a discussion of the important linkages between poaching, wildlife trade, and zoonotic disease risk.

Practical Management of Iron Overload Disorder (IOD) in Black Rhinoceros (BR; Diceros bicornis).

Simple SummaryBlack rhinoceros under human care are predisposed to Iron Overload Disorder that is unlike the hereditary condition seen in humans. We aim to address the black rhino caretaker community at multiple perspectives (keeper, curator, veterinarian, nutritionist, veterinary technician, and researcher) to describe approaches to Iron Overload Disorder in black rhinos and share learnings. This report includes sections on (1) background on how iron functions in comparative species and how Iron Overload Disorder appears to work in black rhinos, (2) practical recommendations for known diagnostics, (3) a brief review of current investigations on inflammatory and other potential biomarkers, (4) nutrition knowledge and advice as prevention, and (5) an overview of treatment options including information on chelation and details on performing large volume voluntary phlebotomy. The aim is to use evidence to support the successful management of this disorder to ensure optimal animal health, welfare, and longevity for a sustainable black rhinoceros population.Critically endangered black rhinoceros (BR) under human care are predisposed to non-hemochromatosis Iron Overload Disorder (IOD). Over the last 30 years, BR have been documented with diseases that have either been induced by or exacerbated by IOD, prompting significant efforts to investigate and address this disorder. IOD is a multi-factorial chronic disease process requiring an evidence-based and integrative long-term approach. While research continues to elucidate the complexities of iron absorption, metabolism, and dysregulation in this species, preventive treatments are recommended and explained herein. The aim of this report is to highlight the accumulated evidence in nutrition, clinical medicine, and behavioral husbandry supporting the successful management of this disorder to ensure optimal animal health, welfare, and longevity for a sustainable black rhinoceros population.

Optimal control problem arises from illegal poaching of southern white rhino mathematical model

In this paper, a novel dynamical population model of a southern white rhino with legal and illegal poaching activity is introduced. The model constructed is based on a predator–prey model with southern white rhinos as prey and humans (hunters) as predators. We divide the southern white rhino population into three classes based on their horn condition. We investigate the existence and the stability of the equilibrium points, which depend on some threshold functions. From an analytical result, it is trivial that arresting as many hunters as possible helps conserve white rhinos, but it comes at a high cost. Therefore, an optimal strategy is needed. The optimal control is then constructed using Pontryagin’s minimum principle and solved numerically with an iterative forward–backward method. Optimal control simulations are given to provide additional insight into the dynamics of the model. Analysis of the cost function effectiveness is conducted using the ACER (Average Cost–Effectiveness Ratio) and ICER (Incremental Cost–Effectiveness Ratio) indicator method. The results show that the hunter population can be more easily controlled with a time-dependent hunter arrest rate rather than by treating it as a constant.

A learning network approach to resolve conservation challenges in the Ngorongoro Conservation Area

The Ngorongoro Conservation Area (NCA) is a protected area and UNESCO World Heritage Site and part of the Serengeti‐Ngorongoro Biosphere reserve in northern Tanzania. It is famous for its large volcanic caldera, unique cultural heritage, early hominid fossils and significant wildlife populations. NCA has been managed as a multiple land‐use area since 1959, a designation intended to foster a harmonious coexistence between indigenous residents and wildlife (Goldstein, 2004).

Evaluating uncertainty in estimates of large rhinoceros populations

Estimates of the numbers of living rhinoceroses inform management interventions. Several techniques assist authorities in obtaining estimates. For large populations, authorities use sample-based methods. Estimates for the number of rhinos living in Kruger National Park (Kruger) make use of sample-based block surveys. Critics of this approach allege that the authorities place sample blocks mostly in areas with high rhino numbers and that this, together with correction for various biases, inflates estimates. The critics also claim that the percentage confidence intervals (PCIs) associated with estimates are too large and propose total area counts as an alternative. We assess these criticisms by comparing the results of a sample-based survey with those of a near concurrent total count. We found that sample surveys appeared to focus on areas with higher rhino densities, but rhino movements in and out of the survey area confounded results. Moreover, total counts do not produce reliable estimates when surveyors fail to account for biases inherent to all sampling procedures. Bias corrections used by sample surveys most likely underestimate the number of rhinos that surveyors miss, contrary to the allegations of critics that sample-based techniques inflate population estimates. Estimates that transparently report uncertainties detected a significant decline in white rhinos from 8,968 (95% CI: 8,394–9,564) in 2013 to 4,116 (95% CI: 2,994–5,726) in 2018. The trends in the black rhino population also indicate a decline from 627 (95% CI: 588–666) in 2009 to 291 (95% CI: 151–441) in 2018. Conducting block-based sample surveys for large populations that correct for biases provides useful information for decision makers. Given that South Africa, specifically Kruger makes substantial contributions to continental rhino numbers, reporting to international bodies such as CITES should transparently include the uncertainties associated with population estimates. Résumé Les estimations du nombre de rhinocéros vivants orientent les interventions de gestion. Plusieurs techniques permettent aux autorités d’obtenir des estimations. Pour les populations importantes, les autorités utilisent des méthodes basées sur des échantillons. Les estimations du nombre de rhinocéros vivant dans le parc national du Kruger (Kruger) s'appuient sur des enquêtes par sondage par blocs. Les détracteurs de cette approche allèguent que les autorités placent les blocs d'échantillonnage principalement dans des zones où le nombre de rhinocéros est élevé et que cela, combiné à une correction pour divers biais, gonfle les estimations. Les critiques affirment également que les intervalles de confiance en pourcentage (ICP) associés aux estimations sont trop importants et proposent comme alternative des comptages totaux des aires. Nous évaluons ces critiques en comparant les résultats d'une enquête par sondage aux résultats d'un comptage total qui a eu lieu presque simultanément. Nous avons constaté que les enquêtes par sondage semblaient se concentrer sur les zones à haute densité de rhinocéros, mais les résultats ont été faussés par le mouvement des rhinocéros dans et hors de la zone d'enquête. De plus, les comptages totaux produisent des estimations non fiables lorsque les enquêteurs ne tiennent pas compte des biais inhérents à toutes les procédures d’échantillonnage. Les corrections de biais utilisées par les enquêtes par sondage sous-estiment probablement le nombre de rhinocéros que les enquêteurs manquent, contrairement aux allégations des critiques selon lesquelles les techniques par sondage gonflent les estimations de population. Des estimations qui rapportent les incertitudes de manière transparente ont détecté une baisse significative des rhinocéros blancs de 8 968 (IC à 95%: 8 394–9 564) en 2013 à 4 116 (IC à 95%: 2 994–5 726) en 2018. Les tendances démographiques des rhinocéros noirs indiquent également un déclin de 627 (IC à 95%: 588–666) en 2009 à 291 (IC à 95%: 151–441) en 2018. Les enquêtes par sondage par blocs qui corrigent les biais et qui sont utilisées pour d’importantes populations, fournissent des informations utiles aux décideurs. Étant donné que l'Afrique du Sud et Kruger contribuent de manière substantielle au nombre de rhinocéros continentaux, les rapports aux organismes internationaux tels que la CITES devraient inclure les incertitudes associées aux estimations des populations de manière transparente.

Development and evaluation of indirect enzyme-linked immunosorbent assays for the determination of immune response to multiple clostridial antigens in vaccinated captive bred southern white rhinoceros (Ceratotherium simum simum)

BackgroundAn overall increase in poaching of white rhinoceros results in captive breeding becoming a significant component of white rhinoceros conservation. However, this type of conservation comes with its own difficulties. When wildlife is captured, transported and/or confined to a boma environment, they are more predisposed to diseases caused by bacterial organisms such as spore forming Clostridium spp. A southern white rhinoceros (Ceratotherium simum simum) population on a captive bred farm was suspected to be affected by Clostridium infections. These endangered animals were apparently exposed to Clostridium spp., in the conservation area previously used for cattle farming. The rhinoceros population on the breeding operation property was vaccinated with a multi-component clostridial vaccine registered for use in cattle. Multiple indirect enzyme-linked immunosorbent assays (iELISAs) were developed in order to evaluate the serum antibody titres of these vaccinated animals. In evaluating vaccine efficacy, the gold standard mouse neutralization test (MNT) was not available and therefore iELISAs were developed for the detection of serum antibodies to C. perfringens type A (alpha toxin), C. chauvoei (whole cell), C. novyi (alpha toxin), C. septicum (alpha toxin) and C. sordellii (lethal toxin) in the white rhinoceros population using international reference sera of equine origin. Antibody titres against each clostridial antigen was evaluated in the vaccinated white rhinoceros population (n = 75). Analytical specificity showed slight cross-reactions for C. chauvoei and C. perfringens type A with the other antigens. Individual assay cut-off values were calculated with 95% confidence. Coefficient of variance (CV) values for both the international reference sera and in-house control sera across all the antigens were well below 16%, indicating good assay repeatability. This convenient and fast assay is suitable for monitoring humoral immune responses to clostridial antigens in vaccinated white rhinoceroses.ResultsCheckerboard titrations indicated optimal antigen and antibody concentrations to be used for each respective iELISA developed. Each titration set of the respective international reference and in-house control sera showed good repeatability with low standard deviations and coefficient of variance values calculated between repeats for each antigen. Individual assays proved repeatable and showed good analytical sensitivity and specificity.ConclusionsThe developed iELISAs are able to evaluate antibody profiles of phospholipase C, C. chauvoei whole cells, TcnA, ATX, TcsL in white rhinoceros serum using international reference sera.

Monitoring rhinoceroses in Namibia’s private custodianship properties

Routinely censusing rhinoceros’ populations is central to their conservation and protection from illegal killing. In Namibia, both white (Ceratotherium simum) and black (Diceros bicornis) rhinoceros occur on private land, in the latter case under a custodianship program of the Namibian Ministry of Environment and Tourism (MET). Black rhinoceros custodian landowners are responsible for the protection of the rhinoceroses on their land and are required to report regularly to the MET. Monitoring imposes a financial burden on custodians yet many of the techniques used involve expensive monitoring techniques that include the need for aerial support and/or animal instrumentation. During May and June 2018, WildTrack undertook a pilot study to census black and white rhinoceros on three private custodianship properties in Namibia. We tested three footprint identification methods for obtaining estimates of rhinoceros populations in an effort to provide less costly alternative monitoring options to rhinoceros custodians. The first was a full monitoring protocol with two components: (a) tracking each individual animal and matching them to their footprints, (b) identifying those individuals from the heel lines on the prints. The second method used simple visual heel line identification ex-situ, and the third method used just an objective footprint identification technique. These methods offer different options of fieldwork labour and cost and were designed to offer monitoring options to custodians that provided information about rhinoceros movement and location, with minimal disturbance to the rhinoceros, and best matched their human and economic resources. In this study, we describe the three methods and report the results of the pilot study to compare and evaluate their utility for rhinoceros monitoring. The first method successfully matched each trail photographed to a known rhinoceros at each site. When the other two methods disagreed with the first, they did so by failing to match single trails to a known rhinoceros, thereby creating fictitious identities consisting of a single trail. This failure occurred twice in one application, but otherwise at most once. We expect this failure can be eliminated through more stringent criteria for collecting photographs of footprints. We also briefly compare the use of footprint monitoring with other commonly used monitoring techniques. On this basis, landowners hosting rhinoceros can evaluate which method best suits their needs and resources.

Private rhino conservation: Diverse strategies adopted in response to the poaching crisis

AbstractPrivate landowners in South Africa conserve roughly 40% of white rhinos globally. Given concerns that escalating poaching has caused private‐rhino owners to disinvest, we used a national survey to assess 171 private‐rhino owners’ responses to the crisis. Twenty‐eight percent of rhino owners are disinvesting in rhino, 57% are pursuing business‐as‐usual (largely ecotourism), and 15% are investing in more rhinos. It is currently unclear whether this diversity in private‐rhino owners’ responses to the crisis is increasing the resilience of the rhino population to poaching. Some rhino investors show signs of financial stress. Most owners support rhino‐horn trade to fund conservation, yet international trade remains banned. By contrast, a recent national policy amendment allows rhinos to be managed as livestock, risking a shift from rhino‐for‐conservation to rhino‐for‐production on private land. Our findings highlight an urgent need to ensure policies keep pace with dynamic socioeconomic environments that influence the sustainability of wildlife use.

Mitochondrial D-loop Genetic Diversity Studies of Rhinoceros unicornis in Assam, India

In Assam wild populations of great Indian rhinoceros are found in three protected areas namely Kaziranga National Park, Orange National Park and Pobitora Wildlife Sanctuary. But it remains an area of investigation whether these three populations are homogeneous or not. To resolve this matter present genetic study was performed on mitochondrial DNA control region by using non invasive dung samples collected from the three natural habitats. The study showed a high level of genetic diversity of rhinoceros population in three habitats of Assam with 24 haplotypes from 196 samples and 21 variable sites in 413bp long nucleotide sequences was recorded. The Fst value also showed differences between the groups; and significant values obtained between Kaziranga and Pobitora with Orang groups. AMOVA analyses revealed the total genetic diversity is 91.62% and diversity between populations is only 8.38%. Thus the higher genetic variability found in Indian rhinoceros populations is important for future survivability, management and translocation to new habitat.