Mineral concentrations in serum/plasma and liver tissue of captive and free‐ranging Rhinoceros species

Mineral implications in health issues of captive rhinos have received much attention lately. This study was undertaken to establish reference values for the mineral status of rhinos. Serum/plasma samples of free‐ranging black (Diceros bicornis) and white (Ceratotherium simum) rhinos and of captive black, white, Indian (Rhinoceros unicornis), and Sumatran (Dicerorhinus sumatrensis) rhinos, as well as liver tissue samples of captive black, white, and Indian rhinos were analyzed for mineral content. Circulating mineral levels of free‐ranging animals were subject to variation according to region. In free‐ranging animals, high molybdenum (Mo) values compared to horse normals were striking. Captive animals displayed even higher circulating Mo concentrations. The significance of iron (Fe) overload in captive specimens of the browsing rhinos (black and Sumatran) was confirmed. Hepatic Fe levels increased in blacks with age. Although this Fe overload is suspected to be linked with diets, the data indicate that this is not due solely to an excessive dietary Fe supply. Whereas the grazing species (white and Indian) had high liver copper (Cu) levels, the browsing species had low to marginal liver Cu concentrations. Liver concentrations of K, Mg, Co, and Mo increased with age in captive black rhinos. Additional findings include high circulating Se levels in all rhino species. Future research should be directed at investigating factors leading to high Fe levels, and at investigating Cu metabolism in captive rhinoceros species. Zoo Biol 24:51–72, 2005. © 2005 Wiley‐Liss, Inc.     

Social and spatial relationships in captive southern white rhinoceros (Ceratotherium simum simum)

Although critical to the conservation of white rhinoceros, captive breeding has proven challenging because of the poor and irregular reproductive health of many captive rhinos, and social interactions may play a significant role. This research investigated the social and spatial relationships of two captive groups of southern white rhinoceros (Ceratotherium simum simum) by examining the frequency of companion changes, the number of space maintenance vocalizations made per hour by each reproductively mature female, and dominant/subordinate interactions. The observed captive rhinos did not change their companionships during the study. They exhibited space maintenance vocalizations and display greater than once per hour, particularly when feeding. Females housed with four calves on 0.033 km² exhibited space maintenance vocalizations more frequently (X±SE = 6.19±0.199/hr) than females housed with one calf and more space (0.06 km², X±SE = 0.55±0.182/hr) and females housed without calves and more space (0.65 km², X±SE = 1.90±0.086/hr). Wider separation of food piles and of females with young calves is suggested to reduce the interpreted spatial stress. The presence of a large number of rhinos in restricted captive space resulted in the formation of herds with dominance hierarchies that were enforced during competition for food and shade. The most subordinate rhino in each of the herds exhibited unusual behaviors such as dung‐kicking and nonestrus urine squirting, and neither has ever reproduced. Suppression of subordinate rhinos might lead to social stress that could negatively impact reproductive success. Zoo Biol 26:487–502, 2007. © 2007 Wiley‐Liss, Inc.     

Alkaline phosphatase as an indicator of true ejaculation in the rhinoceros

The objective was to determine if seminal alkaline phosphatase (ALP) can serve as an indicator of true ejaculation in the rhinoceros. Concentrations of ALP activity were determined in seminal fractions collected from African black rhinos (Diceros bicornis), an African white rhino (Ceratotherium simum), and an Indian rhino (Rhinoceros unicornis) during electroejaculation. In addition, seminal fractions collected during penile massage of a Sumatran rhino (Dicerorhinus sumatrensis) were assessed. Correlations between ALP activity and sperm concentration, fraction pH, and fraction osmolality were evaluated in the Indian rhino and black rhino. Concentrations of ALP activity in rhino ejaculate fractions ranged from < 5 to 11,780 U/L and were positively correlated (P < 0.05) with sperm concentration for both Indian rhino (r = 0.995) and black rhino (r = 0.697), but did not exhibit a strong correlation with either pH or osmolality (P > 0.05). Data were insufficient for establishing meaningful correlation coefficients in the Sumatran rhino and white rhino, but preliminary results were in accordance with findings in the Indian rhino and black rhino. We concluded that ALP was present in rhinoceros semen, likely originated from the epididymides and/or testes, and could serve as a useful tool for assessing the production of ejaculatory versus pre-ejaculatory fluid in the rhinoceros.     

Alkaline phosphatase as an indicator of true ejaculation in the rhinoceros

The objective was to determine if seminal alkaline phosphatase (ALP) can serve as an indicator of true ejaculation in the rhinoceros. Concentrations of ALP activity were determined in seminal fractions collected from African black rhinos (Diceros bicornis), an African white rhino (Ceratotherium simum), and an Indian rhino (Rhinoceros unicornis) during electroejaculation. In addition, seminal fractions collected during penile massage of a Sumatran rhino (Dicerorhinus sumatrensis) were assessed. Correlations between ALP activity and sperm concentration, fraction pH, and fraction osmolality were evaluated in the Indian rhino and black rhino. Concentrations of ALP activity in rhino ejaculate fractions ranged from < 5 to 11,780 U/L and were positively correlated (P < 0.05) with sperm concentration for both Indian rhino (r = 0.995) and black rhino (r = 0.697), but did not exhibit a strong correlation with either pH or osmolality (P > 0.05). Data were insufficient for establishing meaningful correlation coefficients in the Sumatran rhino and white rhino, but preliminary results were in accordance with findings in the Indian rhino and black rhino. We concluded that ALP was present in rhinoceros semen, likely originated from the epididymides and/or testes, and could serve as a useful tool for assessing the production of ejaculatory versus pre-ejaculatory fluid in the rhinoceros.     

Management parameters affecting the reproductive potential of captive,female black rhinoceros,Diceros bicornis

With deterioration of the wild population over the last two decades, captive reproduction of black rhinoceros has become a high priority for zoological gardens. Several reproductive parameters of female black rhinoceros were analyzed with data from the international studbook, and compared to data from field studies. These analyses yielded comparisons for ages of females at first calving, length of birth intervals, and span of reproductive life. The implications for rhino productivity are discussed, and some suggestions for increasing productivity are presented. © 1992 Wiley-Liss, Inc.     

Anthropogenic Influences on Conservation Values of White Rhinoceros

White rhinoceros (rhinos) is a keystone conservation species and also provides revenue for protection agencies. Restoring or mimicking the outcomes of impeded ecological processes allows reconciliation of biodiversity and financial objectives. We evaluate the consequences of white rhino management removal, and in recent times, poaching, on population persistence, regional conservation outcomes and opportunities for revenue generation. In Kruger National Park, white rhinos increased from 1998 to 2008. Since then the population may vary non-directionally. In 2010, we estimated 10,621 (95% CI: 8,767–12,682) white rhinos using three different population estimation methods. The desired management effect of a varying population was detectable after 2008. Age and sex structures in sink areas (focal rhino capture areas) were different from elsewhere. This comes from relatively more sub-adults being removed by managers than what the standing age distribution defined. Poachers in turn focused on more adults in 2011. Although the effect of poaching was not detectable at the population level given the confidence intervals of estimates, managers accommodated expected poaching annually and adapted management removals. The present poaching trend predicts that 432 white rhinos may be poached in Kruger during 2012. The white rhino management model mimicking outcomes of impeded ecological processes predicts 397 rhino management removals are required. At present poachers may be doing “management removals,” but conservationists have no opportunity left to contribute to regional rhino conservation strategies or generate revenue through white rhino sales. In addition, continued trends in poaching predict detectable white rhino declines in Kruger National Park by 2016. Our results suggest that conservationists need innovative approaches that reduce financial incentives to curb the threats that poaching poses to several conservation values of natural resources such as white rhinos.     

Social and reproductive behaviour of critically endangered northern white rhinoceros in a zoological garden

Northern and southern white rhinos have poor reproduction in captivity and social interactions between them, especially increased agonistic behaviour, are believed to be one of the possible reasons. Northern white rhino is currently on the brink of extinction with less than ten animals surviving. We studied the social behaviour of northern white rhinos in zoological garden and investigated the effects of separation of the oldest, wild-born female from the herd on the social behaviour of other group members. After the separation, the numbers of agonistic and the play interactions between the animals significantly increased, no change was found in cohesive behaviour. Our results suggest that a composition of white rhino groups has a significant influence on social interactions between the animals and that better knowledge of proper composition of their groups in captivity in terms of age, sex and wild or zoo origin might improve animals’ well-being and also increase a chance for reproduction.     

Black rhinoceros (Diceros bicornis) in U.S. zoos: II. behavior,breeding success,and mortality in relation to housing facilities

The captive population of black rhinoceros (Diceros bicornis) is not self‐sustaining. The reasons for suboptimal reproduction and high mortality need to be investigated. This can only be achieved by cross‐institutional analyses of environments, behavior, and performance. In this study, we collected data on 23 zoos with black rhinoceros to compare zoo environments with reproductive success, mortality, and behavior. Institutional variation was characterized by enclosure area, percentage of walls around enclosure perimeter, percentage of public access along enclosure perimeter, climate, noise level, number of years zoo has maintained black rhinoceros, frequency of chlorine use, and number of male and female black rhinoceros at a zoo simultaneously. Birth and death rates for each institution were calculated from studbook records. We found that the breeding success of a zoo since 1973 correlated positively with enclosure area, and zoos with two or more females had a lower reproductive rate than zoos with only one female. Females residing during their pre‐reproductive years at a zoo with another reproductive female gave birth for the first time on average 3 years later than sole females. Mortality since 1973 correlated positively with percentage of public access. In Part I, we developed behavior profiles of 29.31 individual black rhinoceros from keeper ratings. Scores for males on the behavior trait Fear also correlated positively to percentage of public access, and we suggest that this aspect of black rhinoceros exhibits is a stressor for this species, especially the males. We found that different aspects of captive environments are associated with male and female black rhinoceros behavior. Male scores on the behavior trait dominant were higher in smaller enclosures, and female scores for a group of behaviors suggesting agitation (chasing/stereotypy/mouthing) were positively correlated with percentage of walls in their enclosure. These two behavior traits were found in Part I to be negatively correlated with the breeding success of an individual male or female. We re‐surveyed the behavior and husbandry of 29 black rhinoceros pairs in zoos 2 years after the original data were collected. The re‐survey confirmed that compatible black rhinoceros pairs are those with assertive females and submissive males, and that enclosure area and a low percentage of concrete walls around the enclosure are positive predictors of a pair's reproductive success. We conclude that temperament traits of individuals and characteristics of their captive environments both have an impact on a pair's breeding success. Our study demonstrates that cross‐institutional comparisons of zoo facilities, when integrated with behavioral assessments of individual animals, are a valuable tool for investigating potential causes of poor reproduction and well‐being in zoo animals. Zoo Biol 18:35–52, 1999. © 1999 Wiley‐Liss, Inc.     

Intake,utilization, and composition of browses consumed by the Sumatran rhinoceros (Dicerorhinus sumatrensis harissoni) in captivity in Sabah,Malaysia

The significant threats to the fewer than 30 wild Dicerorhinus sumatrensis harrissoni, the Bornean sub‐species of the Sumatran rhinoceros, are obvious and include poaching, habitat loss, and environmental changes. Subtle effects on population survival, however, include nutritional or other diseases, which affect morbidity and reproductive success. To address these issues and focus on animals within their natural range, this feeding trial and analysis characterizes the diet fed to the only three captive D. s. harissoni in the world housed at the Sumatran Rhino Breeding Center (SRBC) in Sabah, Malaysia. The study provides an indication of the variance in nutrient composition in local browse, and a comparison with other captive feeding studies. Mean dry matter intake (DMI), comprising ∼90% native browse species, equaled 3.55% (range=2.8–4.1%) of body mass, with a dry matter digestibility averaging 82%. The mean crude protein content of native browses (n=8 spp.) averaged 11.2% (DM basis; range=5–23%, depending on plant part), with available protein measured at 7.8%. Leaves contained significantly (P<0.001) more crude protein, and less (P<0.001) fiber (neutral detergent fiber, acid detergent fiber, and lignin) than twig fractions analyzed, but animals consumed both fractions rather non‐selectively. Of minerals quantified, Na and P were potentially limiting in native browses compared to equid nutrient requirements, and Se may have been marginal. Ca, K, and Fe levels in particular were high in most native browses. Specifically, iron ranged from 45–1,400 mg/kg (mean=230 mg/kg DM), with only three preferred species containing this nutrient at <100 mg/kg. Excess dietary iron has been linked with health issues in browsing rhinos. Additionally, high levels of other minerals (for example Mn, with a mean of 382 mg/kg DM in this study), can precipitate deficiencies in crucial elements such as calcium. In view of the structural and chemical variations of the different parts of the same plants, dietary guidelines should be developed and incorporated into the basic husbandry of these animals that include increasing the number and combinations of species of browse offered daily to adjust for variance in protein, fiber, other nutritional components and food preference, to increasing the quantity of food offered per day based on desired weight gain and reproductive status. This, combined with information on the free‐ranging rhinoceros diet composition, and additional intake and digestibility trials (with concurrent serum analysis to evaluate nutritional status) should greatly assist in providing optimal diets for this highly endangered species. Zoo Biol 0:1–15, 2006. © 2006 Wiley‐Liss, Inc.     

Reserve Size,Conspecific Density,and Translocation Success for Black Rhinoceros

Abstract: Fighting and accidental injury commonly cause black rhinoceros (rhino; Diceros bicornis) death after release. Smaller reserves and higher conspecific density after release (release density) might increase a rhino's encounter rate with hazards like fenced boundaries and conspecifics. We conducted a science-by-management experiment on the influence of reserve size and release density on rates of movement, association, and injury and death amongst 39 black rhinos during the first 100 days after their release into 4 Namibian and 8 South African reserves ranging in size from 670 ha to 45,000 ha. Association rates were negatively related to reserve size and positively correlated with release density. There was also a negative relationship between the proportion of the reserve traversed by individual rhinos and reserve size. In reserves ≥18,000 ha association rates were consistently zero but became elevated in reserves ≤11,500 ha and at release densities ≤9 km²/rhino. Daily displacement did not increase with increasing reserve size >8,500 ha but in smaller reserves daily displacements indicated higher encounter rates by released rhinos with fenced boundaries. Three rhinos received fight-related injuries requiring intervention and 2 of 4 deaths were fight-related. All injuries and 3 deaths occurred in reserves ≤11,500 ha. Model selection based on Akaike's second-order Information Criterion indicated that the parameter release density alone best explained mortality risk. Traditionally considered risk factors, rhino sex, age, and presence of resident conspecifics, were superseded by the risk posed by releases into smaller reserves. Reserves ≤11,500 ha and release densities ≤9 km²/rhino pose an increasing risk to rhino survivorship and so larger reserves and lower densities than these should be favored as release sites.     

Methods of semen collection in an ambulatory greater one-horned rhinoceros (rhinoceros unicornis)

Illegal poaching and reduced habitats have led to the endangered status of rhinoceroses. Collection of semen for preservation and future artificial insemination would therefore increase the reproductive potential of the rhinoceros. Although various collection methods have been attemped with individual rhinos, comparison between methods on a single animal have not been reported. This report details the application of six semen collection techniques on an unsedated and unrestrained greater one-horned rhino. The methods included different types of penile and/or rectal stimulation. Artificial vaginas and an inflatible probe for electroejaculation were specially constructed for semen collection. Of the various methods employed, penile massage consistently resulted in sperm-poor seminal fluid, but when preceded by either rectal massage or electroejaculation, seminal fluid with high sperm concentration was obtained.     

Genetic diversity, phylogeny and conservation of the Javan rhinoceros (Rhinoceros sondaicus)

With a total population of less than 60 individuals limited to two locations, the Javan rhinoceros is perhaps the most endangered large mammal on earth. Although species specific information is crucial to its conservation, its precarious status, habitat inaccessibility, and behavioral adaptations pose major obstacles to its study. Here we report on the first genetic analysis of the two extant populations, in Ujung Kulon, Indonesia, and Cat Tien, Vietnam, and discuss their conservation. As its critically endangered status precluded invasive sampling, we extracted DNA from dung, amplifying and sequencing segments of the mtDNA 12S rRNA gene and the non-coding D-loop. Divergence between Javan rhinos from Ujung Kulon and Cat Tien was similar to that between recognized subspecies of African rhinos, and exceeded that between Sumatran rhinos. The Ujung Kulon and Cat Tien populations represent separate Evolutionary Significant Units, advocating independent management. However, given the precariousness of the Cat Tien population, demographic considerations may override genetic issues in the short term. Genetic diversity of Javan rhinos was low and population expansion in the immediate future will be critical for its survival.     

The birth of the first Sumatran Rhinoceros Dicerorhinus sumatrensis (Fischer, 1814) – London Docks 1872

A Sumatran Rhinoceros (Dicerorhinus sumatrensis) was born in the Victoria Docks of London on board the steamer Orchis arriving from Singapore. It was the first of only eight captive births of this species ever recorded. The female had been captured in Malacca (current Malaysia) together with a male which did not survive the journey. She delivered a female baby unaided by the keeper August Engelke on the evening of Friday 6 December 1872. The rhinos were owned by the animal dealers Carl Hagenbeck and William Jamrach. In London mother and baby were kept in the stables of Charles William Rice on Commercial Road, attended by John Warncken. They were examined by Abraham Dee Bartlett and Frank Buckland, and sketched by Charles Berjeau and an anonymous illustrator working for the Graphic. The baby was crushed to death by her mother on Wednesday 18 December 1872. “Never mind, better luck next time” was the optimistic summary of the Victorian commentators. The female was subsequently sent to America, most probably to be added to one of the menageries operated by P.T. Barnum.     

Assessment of conservation units for the Sumatran rhinoceros (Dicerorhinus sumatrensis)

An assessment of conservation units for the Sumatran rhinoceros (Dicerorhinus sumatrensis) was conducted using a population aggregation analysis (PAA) of mitochondrial DNA site substitutions. Populations were defined as the three geographically separated regions of West Malaysia, Sumatra, and Borneo. The intent of this assessment was to explore management options for this highly endangered lineage rather than conduct a traditional taxonomic revision. Individual DNA positions were not diagnostic for any population. A single haplotype provided a character as support for diagnosing the West Malaysian and Bornean population. The haplotypes on West Malaysia and Sumatra were more similar to each other than either was to the one on Borneo. These data, and a review of the morphological characters, support the option of treating Sumatran rhinos as a single conservation unit, providing managers with greater flexibility in managing the unique Dicerorhine lineage. © 1995 Wiley-Liss, Inc.     

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.     

Mating system in mouse lemurs: theories and facts, using analysis of paternity

Among nocturnal Malagasy prosimians, the grey mouse lemur (Microcebus murinus) is considered a solitary species which has a promiscuous mating system. Indirect indicators, such as the lack of sexual dimorphism, the overlapping of male and female home ranges with each other, the synchronism of seasonal oestrus and the high relative testes size of males, support the presence of sperm competition. In captivity, an intense sexual precopulatory competition develops among males, leading to the emergence of a dominant male who fathers the majority of the litters. Although multiple mating did occur, the dominant male achieved the majority of the matings on the first day of oestrus. A 'mate-guarding' behaviour, exhibited by the dominant male, was observed in 11 groups out of 15, on only the first day of the vaginal opening and was significantly more often directed towards younger females. Females also played an important role in sexual competition among males, since their presence enhances the aggressive interactions between males. Difference in aggressive behaviours of females, in response to male sexual solicitations, suggests female mate choice. Compared with data from wild animals, it may be hypothesised that alternative mating strategies can be used by male grey mouse lemurs to enhance their reproductive success, depending on the availability and distribution of receptive females.     

Gross anatomy of the reproductive tract of female black (Diceros bicornis michaeli) and white rhinoceros (Ceratotherium simum simum)

Reproductive tracts were collected from three black rhinoceros and two white rhinoceros at necropsy. All females were nulliparous, except for one primiparous white rhinoceros. The animals ranged in age from 7 days to 28 years. All nulliparous animals had a constriction in the vaginal canal, which appeared to be a hymen. The primiparous female had only remnants of a hymen. The total length of the tract averaged 102 cm in three adult animals (≥21 years old). The distance from the vulva to the external cervical os averaged 40 cm in these animals. The endometrium of a 28-year-old nulliparous black rhinoceros and a 27-year-old nulliparous white rhinoceros exhibited signs of hyperplasia, whereas this condition was not present in the other animals. It is not known if this condition was related to the fertility of these animals. The cervix of the rhinoceros was firm, and the lumen followed a very tortuous path through eccentric rings of tissue. Visual examination of the ovaries revealed the presence of surface follicles on the ovaries in both species. The overall size of the reproductive tract, especially the vagina and uterine horns, and the extremely tortuous cervical lumen will present obstacles that must be overcome when developing artificial insemination and embryo transfer proceduers for use in rhinoceros.     

Mate Choice in Female Red-necked Pademelons,Thylogale thetis (Marsupialia: Macropodoidea)

Changes in the behaviour of captive female red-necked pademelons, Thylogale thetis, before, during and after oestrus were observed relative to the location of potential male mates. A penned female was presented with four adjacent, individually caged males representing the size classes large, medium, small and subadult. The female's behaviour was videotaped for 8–9 d spanning oestrous (3 d), post-oestrous (3 d) and normal (3 d) sessions of time. Changes in the activity, orientation and location of six penned females, relative to the caged males, were transcribed from videotape. A model of female pademelon behaviour pattern was developed. Results suggest that the females spent a significantly greater amount of time directly in front of the largest available male, relative to the other three smaller males during the oestrous period only, and that a significant proportion of this time was spent involved in active behaviours (grooming and locomotion, compared with inactive behaviours of sitting and scan/sniffing). Although there was a significant preference for females to orientate their bodies away from the location of the males, they faced the males significantly more during oestrus than any other session. Furthermore, the females faced the large male significantly more frequently than any other male. This study provides evidence for mate choice by female red-necked pademelons.