Dental identification and age determination in Elephas maximus

The dentition of an elephant (fossil or extant) can yield clues to the animal's age species identity, provided the teeth are correctly identified. Identifying the serial category of elephant teeth is difficult because the size, shape and position of each tooth changes throughout life, as the teeth form, erupt, wear and move throught the jaw. In the present study, teeth from over 100 museum specimens of the Asian elephant ( Elephas maximus ) were the basis for establishing size ranges for cheek teeth in six serial categories (designated by Roman numerals I to VI). Although the teeth vary greatly and overlap in their dimensions, reliable identifications (as well as estimates of an individual's age in years) can be obtained using three or more measurements. An appreciation for dental variability in Elephas maximus will demand a re-evaluastion of frequently-cited examples of macroevolutionary patterns within the Elephantidae.     

Foraging site recursion by forest elephants Elephas maximus borneensis

Recursion by herbivores is the repeated use of the same site or plants. Recursion by wild animals is rarely investigated but may be ubiquitous. Optimal foraging theory predicts site recursion as a function of the quality of the site, extent of its last use, and time since its last use because these influence site resource status and recovery. We used GPS collars, behaviour and site sampling to investigate recursion to foraging sites for two elephant Elephas maximus borneensis herds in the Lower Kinabatangan Wildlife Sanctuary, Borneo, over a 12 month period. Recursion occurred to 48 out of 87 foraging sites and was most common within 48 hours or between 151-250 days, indicating two different types ofrecursion. Recursion was more likely to occur if the site had previously been occupied for longer. Moreover, the time spent at a site at recursion was the same as the time spent at the site on the first occasion. The number of days that had passed between the first visit and recursion was also positively correlated with how much time was spent at the site at recursion. Habitat type also influenced the intensity of site-use, with more time spent at recursion within riverine/open grass areas along forest margins compared to other habitat types. Recursion is a common behaviour used by the elephants and its pattern suggests it may be a foraging strategy for revisiting areas of greater value. The qualities of recursion sites might usefully be incorporated into landscape management strategies for elephant conservation in the area [Current Zoology 60 （4）： 551-559, 2014].     

Assessment of body condition in Asian elephants (Elephas maximus)

A method of assessing body condition of Asian elephants (Elephas maximus) is presented. The method uses visual assessment to assign numerical scores to six different regions of the body, which are totaled to give a numerical index ranging from 0–11. The relationship between the index and morphometric variables is compared for a sample of 119 juvenile and young adult elephants from southern India, Nepal, and Myanmar. Mean ages of males and females were similar. Mean index of body condition (with standard error [SE]) was 7.3±0.2 points. No significant correlation was found between index of body condition and age over both sexes (r=0.01, n=50). Results were equivalent when sexes were treated separately (females: r=0.03, n=24; males: r=0.01, n=26). Sexes did not differ in height of the shoulder or body condition in our sample, but there was significant sexual dimorphism in breadth of the zygomatic arch and three measures of subcutaneous fat: girth of neck, thickness of cervical fold, and thickness of anal flap. These three measures were also significantly correlated with each other. Our assessment method should prove a practical tool for ecologic studies, but the relationship of the index to percentage of body fat should be determined using heavy water dilution methodology. Zoo Biol 25:187–200, 2006. © 2006 Wiley‐Liss, Inc.     

Blood coagulation profile of the Asian elephant (Elephas maximus)

The coagulation profile of seven Asian elephants was assessed using human reference plasma as a standard. The plasma values for the majority of the coagulation proteins evaluated, including Factors VII, IX, X, and XI, and antithrombin, were similar to that of human plasma. The average Factor VIII:C value was 1.95 units/ml, approximately twice that of the human value. Human recombinant tissue factor was effective as an activator of the tissue factor-factor VII pathway as measured by the prothrombin time assay. The elephant plasma effectively corrected the clotting defect of human Factor XI-deficient plasma but failed to do so with bovine Factor XI-deficient plasma. However, elephant plasma Factor XII was not readily activated by the commercial activated partial thromboplastin time (APTT) reagent formulated with a soluble activator, and consequently the activity of this protein could not be precisely determined. The average (±SD) APTT result of 65.6 ± 9.2 sec was twice as long as that of the human reference plasma. Despite the presence of relatively high levels of fibrinogen, 4.61 ± 0.49 gm/l, no fibrinolytic activity was detected in any of the elephant plasma samples using a standard fibrin plate assay system. © 1996 Wiley-Liss, Inc.     

Sperm sex-sorting in the Asian elephant (Elephas maximus)

In captive Asian elephants, there is a strong need for production of female offspring to enhance reproduction, counter premature aging processes in female animals and reduce challenging management situations derived from husbandry of several bulls in one institution. Artificial insemination of flow cytometrically sex-sorted spermatozoa offers the possibility to predetermine the sex of offspring with high accuracy. The aims of this study were to determine a suitable semen extender and basic parameters for flow cytometrical sex-sorting of Asian elephant spermatozoa. In total 18 semen samples were collected by manual rectal stimulation from one bull. Sperm quality parameters and sex sortability of spermatozoa were evaluated after dilution in three semen extenders (MES-HEPES-skim milk, MES-HEPES, TRIS-citric acid) and DNA staining. MES-HEPES-skim milk was the only semen extender found suitable to sex Asian elephant spermatozoa. From 18 ejaculates collected, 12 were successfully sorted with a purity of 94.5+/-0.7% at an average sort rate of 1945.5+/-187.5 spermatozoa per second. Sperm integrity, progressive and total motility were 42.6+/-3.9%, 48.1+/-3.3%, 59.4+/-3.8% after DNA labelling, and 64.8+/-3.2%, 58.0+/-5.0%, 70.8+/-4.4% after sorting, respectively. After liquid storage of sorted spermatozoa for 12h at 4 degrees C, sperm integrity, progressive and total motility were 46.4+/-5.2%, 32.2+/-4.2% and 58.2+/-3.9%, respectively. The obtained results provide a promising base to inseminate Asian elephants with sexed semen.     

Estrogen metabolism in the Asian elephant (Elephas maximus)

Estradiol-17β metabolism was studied in two female Asian elephants (Elephas maximus). In an initial study, 500 μCi of tritiated estradiol-17β was injected iv into a single animal, and 0, 30 and 60 min serum samples were collected as well as all excreted urine and feces for 24 hr. In a second study, 1.5 mg unlabeled estradiol-17β was injected iv into a second animal and 0, 5, 15, 30, and 60 min serum samples and a 30 min urine sample were collected postinjection. Analyses of samples from both studies demonstrated a rapid conversion of free estradiol to conjugated forms in the serum. The first (5 min) serum sample following the injection of unlabelled estradiol contained unconjugated estradiol: conjugated estradiol: conjugated estrone at a ratio of 60: 29: 10, respectively, and at 30 min a ratio of 33: 43: 24. The urinary estrogen metabolites were in the conjugated form with an estradiol: estrone ratio of 60: 40. No radiolabeled estrogen was found in the fecal samples during the 24 hr following administration of the radiolabeled estradiol. These data indicate a rapid clearance of circulating free estradiol in the elephant, with a major metabolite in the serum and urine being estradiol conjugate. © 1992 Wiley-Liss, Inc.     

Status and conservation of the Asian Elephant Elephas maximus in north-eastern India

A status survey of Asian Elephants Elephas maximus was conducted in the 9 north-eastern states of India. The habitat is contiguous with that in Bhutan, Myanmar and Bangladesh. Although the estimated population of 11 000 elephants is higher than in other regions of the Indian Sub-continent, it is fragmented and a number of small inviable isolated populations have formed. About 35% of the population is partly protected, but protection is inadequate. More areas and migration routes need to be protected. Man–elephant conflict is serious in many areas. A comprehensive Action Plan with a more pragmatic protected-area network has been proposed.     

Identification of bifidobacteria isolated from Asian elephant (Elephas maximus)

Bifidobacteria are considered as one of the key genera in intestinal tracts of animals, and their species composition vary depending on the host. The aim of this study was to identify faecal bifidobacteria from Asian elephants (Elephas maximus), housed in Zoological gardens (Ostrava, Czech Republic). Using culturing, bifidobacteria were found in counts 7.60?±?0.56 log CFU/g. Twenty-six pure strains were isolated from faeces of Asian elephant. The isolates were clustered into two groups according to fingerprinting profiles and fermentation characteristic. Bacteria were identified by a combination of MALDI-TOF MS, PCR methods and sequencing as B. boum (12 isolates) and B. adolescentis (14 isolates). Elephant strains showed different fingerprinting profiles than type and collection strains. Since these two species are frequently isolated from gastrointestinal tract of herbivores, they seem to be typical of animals fed plant diets.     

Demography of captive Asian elephants (Elephas maximus) in southern India

Historically, the Asian elephant has never bred well in captivity. We have carried out demographic analyses of elephants captured in the wild or born in captivity and kept in forest timber camps in southern India during the past century. The average fecundity during this period was 0.095/adult female/year. During 1969–89, however, the fecundity was higher at 0.155/adult female/year, which compares favorably with wild populations. There was seasonality in births with a peak in January. The sex ratio of 129 male to 109 female calves at birth is not significantly different from equality, although the excess of male calves born mainly to mothers 20–40 years old may have biological significance. Mortality rates were higher in females than in males up to age 10, but much lower in females than in males above age 10 years. The population growth rate, based on the lower secundity over the century, was 0.5% per year, and based on the higher secundity during 1969–89, was 1.8% per year. The analyses thus showed that timber camp elephants in southern India could potentially maintain a stationary or increasing population without resorting to captures from the wild. Breeding efforts for elephants in zoos can thus profitably learn from the experience of traditional management systems in part of Asia. Zoo Biol 16:263–272, 1997. © 1997 Wiley-Liss, Inc.     

圈养亚洲象尿液中雌二醇和孕酮含量的周期性变化

针对北京动物园2头圈养雌性亚洲象从未动情的现象,本研究于2003年12月至2005年3月,采用放射性免疫分析法测定了2只不动情象与另一只已受孕象尿液中孕酮和雌二醇的变化,并结合国内外研究探讨圈养亚洲象不动情的原因,为圈养象机构提供相应的繁殖管理建议。研究结果表明,受孕雌象在分娩前一周左右孕酮含量突然升高,后在很短时间内降低,分娩后也维持在较低水平;雌二醇含量分娩前维持在较高水平,分娩前一周骤降,并保持较低水平至本研究结束。非动情象尿液中孕酮和雌二醇水平都显著低于受孕象相应的激素水平,且无明显的波动,推测其卵巢不具活性,导致孕酮与雌二醇水平不具波动性,是这2头圈养雌象未见动情现象的主要原因。     

Home range and ranging behaviour of Bornean elephant (Elephas maximus borneensis) females

Background

Home range is defined as the extent and location of the area covered annually by a wild animal in its natural habitat. Studies of African and Indian elephants in landscapes of largely open habitats have indicated that the sizes of the home range are determined not only by the food supplies and seasonal changes, but also by numerous other factors including availability of water sources, habitat loss and the existence of man-made barriers. The home range size for the Bornean elephant had never been investigated before.

Methodology/Principal Findings

The first satellite tracking program to investigate the movement of wild Bornean elephants in Sabah was initiated in 2005. Five adult female elephants were immobilized and neck collars were fitted with tracking devices. The sizes of their home range and movement patterns were determined using location data gathered from a satellite tracking system and analyzed by using the Minimum Convex Polygon and Harmonic Mean methods. Home range size was estimated to be 250 to 400 km² in a non-fragmented forest and 600 km² in a fragmented forest. The ranging behavior was influenced by the size of the natural forest habitat and the availability of permanent water sources. The movement pattern was influenced by human disturbance and the need to move from one feeding site to another.

Conclusions/Significance

Home range and movement rate were influenced by the degree of habitat fragmentation. Once habitat was cleared or converted, the availability of food plants and water sources were reduced, forcing the elephants to travel to adjacent forest areas. Therefore movement rate in fragmented forest was higher than in the non-fragmented forest. Finally, in fragmented habitat human and elephant conflict occurrences were likely to be higher, due to increased movement bringing elephants into contact more often with humans.     

Causes and correlates of calf mortality in captive Asian elephants (Elephas maximus)

Juvenile mortality is a key factor influencing population growth rate in density-independent, predation-free, well-managed captive populations. Currently at least a quarter of all Asian elephants live in captivity, but both the wild and captive populations are unsustainable with the present fertility and calf mortality rates. Despite the need for detailed data on calf mortality to manage effectively populations and to minimize the need for capture from the wild, very little is known of the causes and correlates of calf mortality in Asian elephants. Here we use the world''s largest multigenerational demographic dataset on a semi-captive population of Asian elephants compiled from timber camps in Myanmar to investigate the survival of calves (n = 1020) to age five born to captive-born mothers (n = 391) between 1960 and 1999. Mortality risk varied significantly across different ages and was higher for males at any age. Maternal reproductive history was associated with large differences in both stillbirth and liveborn mortality risk: first-time mothers had a higher risk of calf loss as did mothers producing another calf soon (<3.7 years) after a previous birth, and when giving birth at older age. Stillbirth (4%) and pre-weaning mortality (25.6%) were considerably lower than those reported for zoo elephants and used in published population viability analyses. A large proportion of deaths were caused by accidents and lack of maternal milk/calf weakness which both might be partly preventable by supplementary feeding of mothers and calves and work reduction of high-risk mothers. Our results on Myanmar timber elephants with an extensive keeping system provide an important comparison to compromised survivorship reported in zoo elephants. They have implications for improving captive working elephant management systems in range countries and for refining population viability analyses with realistic parameter values in order to predict future population size of the Asian elephant.     

Circulating levels of vitamin E in captive Asian elephants (Elephas maximus)

Circulating levels of α-tocopherol (vitamin E) were examined via high-performance liquid chromatography in four female Asian elephants (Elephas maximus) at the New York Zoological Park between 1983 and 1987. Plasma vitamin E averaged 0.08 μg/ml in 1983, and was considered deficient. Over a four-year period of dietary supplementation ranging from 0.7 to 3.7 IU vitamin E/kg body mass (approximately 50 to 250 IU/kg diet as fed), mean plasma α-tocopherol increased to 0.6 μg/ml. Plasma and dietary vitamin E were found to be significantly correlated (p < 0.025) in these animals. Serum or plasma vitamin E measured in an additional 20 elephants from eight other zoological institutions in the United States and Canada averaged 0.5 μg/ml, but values were not significantly correlated (p > 0.05) with calculated dietary levels of the vitamin. To achieve the mean value for circulating α-tocopherol in captive elephants (0.5 μg/ml), feed must provide at least 1.0, and more likely 2.0 to 2.5 IU vitamin E/kg body mass (approximately 130 to 167 IU/kg diet).