Reproduction of the African Elephant
About: This article is published in Nature.The article was published on 1965-03-01 and is currently open access. It has received 12 citations till now. The article focuses on the topics: African elephant.
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TL;DR: Although the musth periods of male elephants are asynchronous the phenomenon can functionally be considered a rutting period, and the physical and behavioral manifestations of musth in elephants are similar to those described for other male mammals during rut.
Abstract: 1. The physical and behavioral characteristics and the temporal patterning of musth were studied over a ten-year period in a free-ranging population of African elephants. 2. Males spent more time in association with females during musth than during non-musth periods. 3. Males were more aggressive during their musth periods than during non-musth. 4. The occurrence and duration of musth were age-related: no male under 24 years was seen in musth; bouts of must among younger individuals were short and sporadic, while older males experienced longer more predictable periods of musth on an annual basis. 5. Although males in musth were observed year-round, the frequency of musth males was highest during and following the two rainy seasons and, in general, good rainfall years had higher frequencies of males in musth than did poor rainfall years. 6. The number of males in musth per month correlated closely with the number of females observed in estrus. However, since the period of estrus lasts only four to six days (Moss, 1983), while musth may last several months, the onset of musth was not necessarily triggered by the onset of estrus in a particular female. 7. The musth periods of different males were asynchronous and each male came into musth at a specific time of year. This period was relatively consistent from one year to the next, particularly among the older males. 8. Males in musth advertised their heightened sexual and aggressive state through visual and olfactory signals and by vocalizing. It is suggested that these signals function to announce identity, condition and location to both rival males and to potentially receptive females. 9. The physical and behavioral characteristics and temporal patterning of musth in African and Asian elephants are compared and found to be remarkably similar. 10. The physical and behavioral manifestations of musth in elephants are similar to those described for other male mammals during rut. Since estrus in female elephants is less clumped relative to most ungulates, male elephants have a different temporal pattern of rutting. Although the musth periods of male elephants are asynchronous the phenomenon can functionally be considered a rutting period.
220 citations
Cites background from "Reproduction of the African Elephan..."
...The discussion of musth in African elephants has been further con¬ fused by the incorrect use of the term, which in this species has often been used to refer to temporal gland secretions (Osman-Hill, 1953; Kurt, 1974; Buss et al., 1976) rather than to a behavioural syndrome as was originally intended in Asia (Sanderson, 1882; Evans, 1901)....
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Journal Article•
TL;DR: The detection of the location and description of the testes may provide information for modifying present castration procedures and ultrasound examination of the male accessory glands may aid in the identification of potential semen donors for assisted reproduction programs in captive elephants.
Abstract: Transrectal ultrasonography was performed on five wild and two captive male African elephants (Loxodonta africana) and four captive male Asian elephants (Elephas maximus) to develop standards for assessment of reproductive health and status. The entire internal urogenital tract was visualized ultrasonographically by using a 3.5 MHz or a 7.5-MHz transducer in combination with a probe extension adapted for elephant anatomy. The findings were verified by postmortem ex situ ultrasound examinations in several individuals of each species. Each part of the internal urogenital tract was sonographically detectable except for the bulbourethral glands and the cranial portion of the ureters and ductus deferentes, which were only observed in situ in the neonate. Each structure visualized was measured and described. The size and morphology of the urogenital structures, especially the accessory glands, were indicative of breeding status, if known. There was a notable difference between African and Asian males in the size and morphology of the prostate gland and a slight difference in the shape of the ampullae. No other structure showed significant species differences. The detection of the location and description of the testes may provide information for modifying present castration procedures. Furthermore, ultrasound examination of the male accessory glands may aid in the identification of potential semen donors for assisted reproduction programs in captive elephants.
38 citations
TL;DR: By combining ultrasonography and morphology, this work has been able to produce the first reliable criteria for estimating gestational age and ontological development of Asian and African elephant foetuses during the first third of gestation.
Abstract: Elephants have the longest pregnancy of all mammals, with an average gestation of around 660 days, so their embryonic and foetal development have always been of special interest. Hitherto, it has only been possible to estimate foetal ages from theoretical calculations based on foetal mass. The recent development of sophisticated ultrasound procedures for elephants has now made it possible to monitor the growth and development of foetuses of known gestational age conceived in captivity from natural matings or artificial insemination. We have studied the early stages of pregnancy in 10 captive Asian and 9 African elephants by transrectal ultrasound. Measurements of foetal crown-rump lengths have provided the first accurate growth curves, which differ significantly from the previous theoretical estimates based on the cube root of foetal mass. We have used these to age 22 African elephant foetuses collected during culling operations. Pregnancy can be first recognized ultrasonographically by day 50, the presumptive yolk sac by about day 75 and the zonary placenta by about day 85. The trunk is first recognizable by days 85-90 and is distinct by day 104, while the first heartbeats are evident from around day 80. By combining ultrasonography and morphology, we have been able to produce the first reliable criteria for estimating gestational age and ontological development of Asian and African elephant foetuses during the first third of gestation.
32 citations
Cites background or methods from "Reproduction of the African Elephan..."
...Soc. B (2007) cross-section, placental tissue protruded in the chorioallantoic cavity beginning on day 85 of gestation....
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...Foetal age for these specimens was calculated on the basis of foetal mass according to Huggett/Widdas (using the foetal growth velocity as determined by Perry 1953) and Craig....
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...Perry (1953) determined that the ‘specific foetal growth velocity’ for both African and Asian elephants was 0.08, given that the average weight at birth is 120 kg and the gestation length is 22 months....
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...TheHuggett/ Widdas formula (using the foetal growth velocity as determined by Perry 1953) gave ages that were approximately 20 days younger than the known age (figure 1b)....
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TL;DR: The Quaternary fossil record of Águas de Araxá is represented by an accumulation of skeletal elements of several sizes, which are assigned to a population of Stegomastodon waringi, which is considered as an aggregation of family units, which suggests a time of low environmental humidity.
Abstract: The Quaternary fossil record of Aguas de Araxa (QAA) is represented mainly by an accumulation of skeletal elements of several sizes, which are assigned to a population of Stegomastodon waringi. We analyzed 97 molars according to the wear stages of Simpson and Paula-Couto (1957), and developed a morphometric wear index. The population structure (proportion of immature, subadult, adult, mature adult and senile adult individuals) was identified, and these five age classes were compared to those of extant elephant populations and defined with social implications. The analysis made possible to establish that the population is largely composed of adults: 14.89% are immature individuals, 23.04% subadults, 27.65% adults, 17.21% mature adults and another 17.21% senile adults. Based on population structure, we do not discard the possibility that the fossil population was stable or in recovery, and/or was experiencing a high-predation period on younger individuals. The number of individuals composing the past population studied here could suggest that the occupied environment was open due to comparisons to populations of extant elephants. We consider this population as an aggregation of family units, which suggests a time of low environmental humidity. Based on literature and our findings, their extinction appears to be regional and probably related to a catastrophic event.
30 citations
TL;DR: The GnRH vaccination protocol failed to induce anoestrus in the treated female elephants, indicating that irregular oestrous cycles occur amongst free-ranging elephants and are not restricted to elephants in captivity.
Abstract: Background
In southern Africa, various options to manage elephant populations are being considered. Immunocontraception is considered to be the most ethically acceptable and logistically feasible method for control of smaller and confined populations. In this regard, the use of gonadotropin-releasing hormone (GnRH) vaccine has not been investigated in female elephants, although it has been reported to be safe and effective in several domestic and wildlife species. The aims of this study were to monitor the oestrous cycles of free-ranging African elephant cows using faecal progestagen metabolites and to evaluate the efficacy of a GnRH vaccine to induce anoestrus in treated cows.
24 citations