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Journal ArticleDOI

Occurrence of placental scars in the uterus of the african elephant (loxodonta africana)

01 Dec 1967-Reproduction (Society for Reproduction and Fertility)-Vol. 14, Iss: 3, pp 445-449

AboutThis article is published in Reproduction.The article was published on 1967-12-01 and is currently open access. It has received 19 citation(s) till now. The article focuses on the topic(s): African elephant.

Topics: African elephant (65%)

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Journal ArticleDOI
TL;DR: The analysis of the elephant populations in north Bunyoro indicates that they are at densities in excess of the carrying capacities of the habitats, and the continuing changes in these habitats are described.
Abstract: Summary The paper is concerned with the changing relation between elephant populations and vegetation in north Bunyoro, Uganda. The history of the area over the past 100 years is briefly described, particularly in terms of changing human populations and contraction of the elephant range. The main features of the environment, including vegetation types and distribution, annual burning, other species of large mammals (including the results of aerial counts) and birds are described. The main results of investigations on the elephant populations in the area, dealing with numbers, distribution and movements, population density distributions, and social organisation iocluding group size frequencies and structure, are presented. From a population of about 10,000 elephants over 1,000 have been cropped or shot on control in the area since 1965. The results of detailed analyses of material derived from these operations are presented and discussed. Material from the cropping operations represents a cross-section of the population and all animals sampled have been aged from the dentition. It is concluded that the mean daily food intake (wet weight) is 4% of live weight for all classes except lactating females; results of studies of food quality are discussed and a possible explanation for the de-barking of trees presented. The physical condition of elephants in several populations has been compared and appears to be poorer when less browse is available. Growth equations are presented for height and weight; the male shows a post-pubertal growth spurt. Various reproductive parameters are examined including age at puberty, pregnancy rate, and the seasonal cycle. Seasonal conceptions are delayed in North Bunyoro in relation to their timing north of the River Nile and it is suggested that the delay is nutritionally-induced. Recruitment has been falling in this population and this decline is likely to continue in the absence of effective management. Some undesirable consequences of extensive control-shooting are mentioned. The analysis of the elephant populations indicates that they are at densities in excess of the carrying capacities of the habitats, and the continuing changes in these habitats are described. In the grassland and wooded grassland areas the destruction of woodland has progressed radially, a zone of damage about 15–20 km wide having moved outwards through the range. This is consistent with destruction mainly by elephants rather than by fire. The influence of elephants on the forest edge and on the areas of regeneration inside the forest, created by management, is described. Finally specific proposals that have been presented to the National Parks and Forest Department are discussed. These involve rational cropping of over 4,000 elephants over the range and the construction of elephant-proof barriers, the control of fire, and the declaration of a Conservation Area with a statutory Authority on which the various interests concerned would be represented.

100 citations


Journal ArticleDOI
TL;DR: Although many of these bulls could serve as semen donors for natural mating or artificial insemination, the inconsistent production of good-quality ejaculates raises questions as to the reliability of these individuals to participate in breeding programs.
Abstract: The success rate of captive elephant breeding programs worldwide is poor. Along with undiagnosed reproductive disorders in females and fatal diseases such as the newly discovered herpesvirus infection, male infertility now is considered a major contributing factor in the failure to maintain self-sustaining captive populations. To address questions related to male reproductive dysfunction, approximately 309 ultrasonographic assessments combined with semen collection were performed in captive (n = 10) and wild (n = 4) African (Loxodonta africana) and captive (n = 61) Asian (Elephas maximus) elephants. Bulls ranged from 4 to 50 years of age and were examined at 9 institutions in North America, 13 in Europe, 2 in Africa, and 7 in Asia. About half of the reproductive assessments were performed in protected contact situations with elephants handled in a restraint device, and half involved assessments of trained Asian bulls managed in free contact. Four wild African and two Asian elephant bulls were evaluated after receiving general anesthesia. Transrectal ultrasound was used to characterize the morphology and functionality of the entire urogenital tract, including the testes and accessory sex organs. Bulls were categorized on the basis of breeding status (breeders vs. non-breeders) and social history (i.e., type of interaction with conspecifics and keepers). Most of the bulls were non-breeders (designated Types I–V). Type I (n = 3 African, 6 Asian) and Type V (n = 1 Asian) were immature and castrate, respectively. On the basis of keeper evaluations, Type II bulls (n = 2, 4) were subordinate to older cows and keepers, whereas Type III bulls (n = 4, 28) were dominated by other bulls. Type IV (n = 1, 8) were older bulls of unknown history that exhibited numerous testicular pathologies resulting in poor semen quality. Non-breeding bulls included those that were exposed to females, but failed to breed, as well as those that had no opportunities to breed. Type VI individuals (n = 4, 14) were proven breeders. The percentage of observable reproductive tract pathology in adult males was remarkably low (14%), even in older bulls. However, apparent infertility of non-organic cause (i.e., not due to specific anatomical abnormalities) in these otherwise healthy bulls was high (32%). Semen quality varied markedly in ejaculates collected from the same bull, as well as from different bulls. In conclusion, although many of these bulls could serve as semen donors for natural mating or artificial insemination, the inconsistent production of good-quality ejaculates raises questions as to the reliability of these individuals to participate in breeding programs. The apparent inhibitory effect of suppressive social interactions on reproductive potential also needs to be investigated. Ultrasound examinations combined with semen collection should be conducted periodically to estimate the reproductive value of each bull and determine whether altered management strategies are needed to enhance captive breeding. Zoo Biol 19:333–345, 2000. © 2000 Wiley-Liss, Inc.

90 citations


Journal ArticleDOI
TL;DR: Study of the gonads of 108 dugongs from north Queensland indicates that neither females nor males are continuously in breeding condition, suggesting that the gonadal activity of males in a population is not synchronized.
Abstract: Study of the gonads of 108 dugongs from north Queensland indicates that neither females nor males are continuously in breeding condition. The gonadal activity of males in a population is not synchronized. Ovaries tend to be active in the latter half of the year. There is no evidence for females coming into oestrus soon after giving birth but conception can occur during lactation. In the Townsville-Cairns area, dugongs calve from August-September through December. Neonates are between 1.0 and 1.3 m long and weigh 20-35 kg. Dugongs of both sexes less than 2.2 m long are likely to be immature, those over 2.5 m long are probably mature, and the status of animals between 2.2 and 2.5 m long is uncertain. The pre-reproductive period seems to be very variable but is a minimum of 9-10 years for both sexes. The gestation period is about 1 year and lactation can last at least 1.5 years. The usual litter size is one. The secondary and tertiary sex ratios are 1:1. Estimates of the calving interval based on pregnancy rates, the rate of accumulation of placental scars, and calf counts from aerial surveys and photographs, range from 3 to 7 years for various populations. A simple population model has been used to calculate the relationship between calving interval and adult mortality rate for stationary populations with different pre-reproductive periods and juvenile mortality rates. Even the most optimistic schedule of reproduction and juvenile mortality demands an adult survivorship of about 90% per year for population maintenance.

88 citations


Journal ArticleDOI
01 Jan 2000-Oryx
TL;DR: The history of the Addo elephant population in South Africa, from the creation of the AENP in 1931 to the present (every elephant currently living within the park is known), was reconstructed and data on annual recruitment and mortality are considered sufficiently reliable for use in analyses of the population's growth and recovery.
Abstract: The history of the Addo elephant population in South Africa, from the creation of the Addo Elephant National Park (AENP) in 1931 to the present (every elephant currently living within the park is known), was reconstructed. Photographic records were used as a primary source of historical evidence, in conjunction with all documentation on the population. Elephants can be identified in photographs taken throughout their life by study of the facial wrinkle patterns and blood vessel patterns in their ears. These characteristics are unique for each elephant and do not change during the individual's life. The life histories of individual elephants were traced: dates of birth and death were estimated and, wherever possible, the identity of the individual's mother was ascertained. An annual register of elephants living within the population, from 1931 to the present, was compiled, and maternal family trees constructed. Preliminary demographic analyses for the period 1976–98 are presented. The quantity and quality of photographs taken during these years enabled thorough investigation of the life histories of all elephants. Prior to 1976, insufficient photographs were available to provide reliable data on the exact birth dates and mothers' identities for every calf born. However, data on annual recruitment and mortality are considered sufficiently reliable for use in analyses of the population's growth and recovery.

85 citations


Journal ArticleDOI
TL;DR: Current knowledge of elephant reproduction is reviewed and how it is being used to aid species conservation for maximal reproductive efficiency and enhancement of genetic management is reviewed.
Abstract: Elephants possess many unique qualities, including some that relate directly to their reproductive biology. Thus, comparative studies on elephants provide valuable information to the growing biological database for extant mammals. Left undisturbed, Asian Elephas maximus and African Loxodonta Africana elephants reproduce well in the wild. It is ironic then that most captive populations face possible‘extinction'because of historically poor reproductive performance. Some of the problems with breeding elephants in captivity are logistical but others, like ovarian and uterine pathologies and bull infertility, have management-related aetiology. Through advances in endocrine monitoring and ultrasound imaging techniques, we are beginning to understand some of the complex mechanisms controlling reproductive function in elephants. Several reproductive characteristics appear to be unique to the taxon, such as luteal steroidogenic function, follicular development patterns, pituitary gonadotrophin secretion, a 22 month-long gestation and musth (in ♂♂). One example is the‘double LH surge'occurring 3 weeks apart during the follicular or non-luteal phase of the cycle, with only the second surge inducing ovulation. These qualities have at times both enhanced and hampered efforts to understand and control reproduction. We have learned that techniques developed for domestic or laboratory species are not always directly applicable to elephants. However, the recent success of artificial insemination based on new ultrasound and endocrine methodology offers hope that establishing selfsustaining populations is possible. This paper reviews our current knowledge of elephant reproduction and how it is being used to aid species conservation for maximal reproductive efficiency and enhancement of genetic management.

75 citations


References
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Journal ArticleDOI
TL;DR: The findings are discussed with reference to the phylogenetic position of the genus, the probable role of the corpus luteum in pregnancy, and the significance of the results in relation to the conservation of existing wild elephant populations.
Abstract: Between December 1946 and December 1948, and January to March 1950, 150 elephants made available in the course of control work carried out by the Uganda Game Department were examined in greater or less detail according to circumstances. Eighty-one were females, of which sixty-seven were adult and thirty-one had an embryo in the uterus. All the dissections were carried out in the field, and the present account includes observations on the terrain, the food of the elephant, and other aspects of its ecology. Linear measurements of the carcasses and photographs of the molar teeth provide a guide to the age of specimens. Tusk growth is nearly similar in males and females until puberty, after which those of females generally cease to grow. The reproductive organs of the male are briefly described; those of the female are described in more detail, and discrepancies between existing accounts are considered in the light of this relatively extensive series of specimens. The mode of formation of the ovarial sac is unusual and is described from foetal, neonatal and adult specimens. There is marked hypertrophy of the interstitial tissue of the foetal gonads during the later stages of gestation. Breeding occurs at all times of year, but mating is possibly more frequent in the period December to March than at other times. Both sexes reach maturity at 8 to 12 years, and the female continues to breed until old age. Parturition is followed by a lactation anoestrus, after which the female undergoes a number of brief oestrous cycles until pregnancy ensues, lactation being continued throughout the subsequent gestation period. The interval between parturition and subsequent conception is normally of the same order of duration as the gestation period, and the normal calving interval appears to be rather less than four years. The ovarian cycle of the adult is characterized by the occurrence of multiple ovulation and the presence of many apparently active and histologically indistinguishable corpora lutea in both ovaries at all the stages of pregnancy which were encountered. It is probable that the corpus luteum of pregnancy develops from one of a number of follicles which ovulate under the same hormonal stimulus, and that it persists together with the accessory corpora lutea, some of which arise from follicles which ovulate and some from follicles which luteinize without ovulating. The corpora lutea are replaced about mid-pregnancy by a second set, which are formed by the luteinization of all the follicles with antra in both ovaries; some at least of the larger ones ovulate while many smaller ones do not. Follicular growth is suppressed in the later stages of pregnancy. The cycle of events bears some resemblance to that which occurs in the mare, and the comparison is discussed in detail. The ovarian periphery is characterized by numerous subsurface crypts and papillose projections which increase the area of the germinal epithelium. A description of the placenta and foetal membranes is in preparation, and preliminary study reveals a striking similarity to Hyrax , particularly in the quadri-lobulate allantois. The findings are discussed with reference to the phylogenetic position of the genus, the probable role of the corpus luteum in pregnancy, and the significance of the results in relation to the conservation of existing wild elephant populations.

123 citations


"Occurrence of placental scars in th..." refers background or methods in this paper

  • ...INTRODUCTION The elephant placenta is vasochorial, rather than, in the strict sense, endotheliochorial (Amoroso & Perry, 1965) and as Perry (1953) remarks in an earlier paper: "It is clear . . . that a considerable amount of maternal tissue comes away with placental tissue of foetal origin when the…...

    [...]

  • ...For Western Uganda the material collected by Perry (1953) indicated a Downloaded from Bioscientifica.com at 04/27/2019 02:50:21PM via free access Placental scars in the elephant 449 mean calving interval of 3-8 years in the years 1947 to 1950; current research on the same populations suggests that…...

    [...]

  • ...The elephant placenta is vasochorial, rather than, in the strict sense, endotheliochorial (Amoroso & Perry, 1965) and as Perry (1953) remarks in an earlier paper: "It is clear ....

    [...]

  • ...For Western Uganda the material collected by Perry (1953) indicated a...

    [...]


Journal ArticleDOI
01 Mar 1965-Nature

12 citations