Rainfall and the population dynamics of elephant dung‐piles in the forests of southern Ghana

Decaying dung‐piles were observed at three sites in the lowland forests of southern Ghana. Time to disappearance was inversely related to rainfall in the month of deposition. The monthly survival of each age‐class decreased with age and was inversely proportional to rainfall in the month of deposition. A simulation revealed that if elephant numbers and defaecation rates are constant, then dung density in a given month will be governed by rainfall in the two preceding months. Changes in annual rainfall and its monthly distribution in southern Ghana mean that dung‐pile densities will vary from one month to the next, and between the same months in different years, even if elephant numbers are constant. Thus dung counters must take rainfall into account. A new method of censusing elephants in Ghana is presented, and suggestions are made for improving elephant counts in central African forests.     

Temporal patterns of crop raiding by elephants: a response to changes in forage quality or crop availability?

Temporal patterns of crop raiding by elephants were studied for 13 months in 1996/1997 at Kibale Forest National Park, Uganda. To determine the influence of environmental factors on the timing of raiding, we tested for correlations between crop raiding patterns and the quality of natural forage within the forest as well as crop availability beyond park boundaries. Crop raiding occurred throughout the year with peaks in dry seasons when crop availability was high. Bananas and maize were the main crops raided. Variations in forage quality were moderate with small seasonal fluctuations and peaks in dry seasons. Monthly crop raiding incidences were not influenced by forage quality but by ripening of maize. Comparison of forage quality and temporal distribution of crop raiding between savanna and forest habitats suggests that crop availability is more important in forest habitats, whereas in savanna habitats large seasonal fluctuations in forage quality have a greater influence on temporal patterns of crop raiding.     

Effects of large herbivores and fire on the regeneration of Acacia erioloba woodlands in Chobe National Park, Botswana

Acacia erioloba woodlands provide important forage and shade for wildlife in northern Botswana. Mortality of mature trees caused by browsing elephants has been well documented but the lack of regeneration of new trees has received little attention. Annual growth of new shoots and changes in height were measured to determine the influence of elephants and small ungulate browsers, rainfall and fire on the growth and survival of established A. erioloba seedlings from 1995 to 1997 in the Savuti area of Chobe National Park. All above‐ground vegetation was removed from 40% of established seedlings in 1995 and 28% in 1997 by browsing elephants, and the mean height of remaining seedlings decreased from >550 mm to <300 mm. When seedlings browsed by kudu, impala and steenbok but not elephants are considered, mean seedling height increased <50 mm per year, even though mean new shoot growth remaining at the end of the dry season was 100–200 mm. Fires burned portions of the study area in 1993 and 1997, killing above‐ground vegetation, but most established A. erioloba seedlings survived, producing coppice growth from roots. While elephants and fire caused the greatest reduction in established seedling height and number, small browsers suppressed growth, keeping seedlings vulnerable to fire and delaying growth to reproductive maturity.     

北京地区恒河猴试验性繁殖及部分生物学特性观察

本实验于1992年底开始,通过选种、选配,建立了一个11只雄猴,77只雌猴的恒河猴生产繁殖种群并对其繁殖性能进行了观察与研究。三年间,利用大笼群养的“后宫式”繁殖方法,母猴怀孕107例,流产11例,生产仔猴96只,离乳94只。平均妊娠率、产仔率、离乳率分别为51．44％、46．15％、97．92％。在“后宫式”群养方式繁殖成功后,我们又尝试了单笼饲养、定期交配的新的繁殖方法,当年投种9只母猴,怀孕7只,生产7只。怀孕率、生产率均为77．78％。在进行实验性繁殖的同时,对人工条件下饲养的恒河猴的部分生物学特性如妊娠期、月经周期、血液生理生化指标、生长特性等进行了观察、记录和统计。结果表明人工条件下饲养的恒河猴在每年11月至次年4月间交配,4月至9月分娩。恒河猴具有间情期,每年秋冬季发情,平均月经周期为28．31±2．82d（n＝70）。平均怀孕期为163．46±11.87d（n＝13）。本实验为人工繁殖恒河猴进而实现实验动物化积累了基础数据,为将来提供高等级的、遗传背景清楚的、高质量的实验猕猴奠定了工作基础。     

Experience in the Ivermectin Treatment of Internal Parasites in Zoo and Captive Wild Animals: A Review

The selection and the use of antiparasitic remedies in the animals in zoological gardens and those bred in captivity present one of the challenges to the wildlife veterinarians. The latter have to be flexible enough in the choice of medicines and schemes of treatment of the animals they take care of. The present study is aimed at adding more information in that respect. A number of cases of ivermectin treating of mammals, birds, reptiles, amphibians and fish bred in captivity are presented in it. The tolerance to the drug in the different animals, species of the parasites influenced by it, dosages, schemes of applying and some other peculiarities in the system animals – diseases – anthelmintic treatments are discussed.     

Horizontal tooth displacement and premolar occurrence in elephants and other elephantiform proboscideans

Abstract

Modern elephants lack permanent premolars and their cheek teeth succeed one another by an unusual horizontal tooth displacement mechanism. The fossil record demonstrates that this mechanism characterises elephantimorph proboscideans and first evolved in the late Oligocene. Horizontal tooth displacement provides elephantimorphs with an adaptive advantage over more primitive proboscideans with vertical tooth replacement and concurrent function of all adult teeth. Premolars were lost convergently in diverse elephantimorph taxa with small or no lower tusks and foreshortened symphyses, including independently in crown elephant genera. New evidence reveals the presence of premolars in early species of Loxodonta and loss of premolars in the Loxodonta clade by the mid-Pliocene. Rare occurrences of premolars in mammoths support the hypothesis that these teeth were lost by suppression of genetic and molecular processes responsible for their development. Retention of premolars in Elephas planifrons indicates independent loss of premolars in Elephas and mammoths, and that Elephas had multiple migrations out of Africa, once pre- and once post-loss of premolars in the genus. Unfortunately, the effects of dwarfing are thought to obscure the phylogenetic affinities of fossil elephants from Sulawesi and Java in the genus Stegoloxodon that retain permanent premolars.     

The sleeping policeman: understanding issues of enforcement and compliance in conservation

Rules governing human behaviour are at the heart of every system of natural resource management. Without compliance, however, rules are meaningless so effective enforcement is essential if conservation is to be successful. There is a large body of theory concerning enforcement and compliance with rules spread over several disciplines, including psychology, economics and sociology. However, there have been few attempts to extend this theory to conservation applications and there is little practical guidance for managers and conservation planners on the optimal design of enforcement programmes. We review approaches to understanding why individuals break rules and how optimal policy choices can reduce rule-breaking, highlighting research which has specifically dealt with natural resources. Because of the difficulty of studying rule-breaking behaviour directly, modelling approaches have been particularly important and have been used to explore behaviour at the individual, group and institutional levels. We illustrate the application of models of enforcement and compliance to conservation using the African elephant Loxodonta africana as a case study. Further work is needed to create practical tools which can be applied to the design of enforcement measures in conservation. Particular challenges include understanding the importance of violations of rationality assumptions and incorporating intertemporal choice in models of decision making. In conclusion, we argue that a new field of robust theory and practice is urgently needed to ensure that issues of enforcement and compliance do not undermine conservation initiatives.     

Use of genetic tags to identify captive-bred pallid sturgeon (<Emphasis Type="Italic">Scaphirhynchus albus</Emphasis>) in the wild: improving abundance estimates for an endangered species

The ability to distinguish captive-bred and natural-origin individuals in the wild is critical for evaluating the impact of captive breeding programs on natural populations. Continued persistence of endangered pallid sturgeon (Scaphirhynchus albus) in the Missouri River is largely dependent on captive breeding efforts that spawn natural-origin adults in fish hatcheries and release their progeny into the wild. Prior to release, hatchery-origin individuals are physically marked so they can be distinguished from natural-origin individuals when recaptured. During the years 2004–2006, 24 unmarked juvenile pallid sturgeon tissue samples were collected in the Missouri River downstream of Gavins Point Dam, South Dakota, USA that were presumed natural-origin. However, these individuals were similar in size to hatchery-origin fish released in this area raising concerns that these individuals were actually hatchery-origin fish with lost or malfunctioning tags. We used microsatellite based parentage analysis to determine if the unmarked fish were members of hatchery families that had been released in this area. This retrospective genetic tagging approach revealed that 23 of 24 unmarked fish were indeed hatchery-origin. The origin of the remaining individual remains unknown because genetic samples were not available from all of the families released below the dam and the unassigned fish may have originated from one of these un-sampled families. These results provide important insight into the conservation status of endangered pallid sturgeon as well as provide data important for guiding management decisions. Our results also demonstrate the efficacy of using genetic tags as an alternative or complimentary approach to physically marking individuals.     

Elephant (Loxodonta africana) footprints as habitat for aquatic macroinvertebrate communities in Kibale National Park,south‐west Uganda

This is the first study where elephant footprints as habitat for aquatic macroinvertebrate communities were assessed. Preliminary observations during the dry season in Kibale Forest, Uganda, indicated that water‐filled footprints constituted the majority of stagnant ponds. Consequently, this study aimed at giving an overview of the diversity and ecology of those habitats and the capacity of elephants as ecosystem engineers. The fauna and abiotic factors (age, size, substrate, organic matter, pH, canopy cover, temperature, conductivity) of 30 water‐filled natural elephant footprints were sampled, resulting in the record of 61 morphospecies among 27 families/orders. Species composition was dominated by Hydrophilidae and Dytiscidae and influenced by environmental variables, such as age and organic matter. To study the colonization process, 18 artificial footprints were created within different distances from the water source. After 5 days, 410 specimens were collected, with higher species richness in artificial footprints closer to a natural water source. We conclude that colonization of water‐filled footprints is fast, they constitute important habitats with high diversity and variability, and they act as stepping stones for dispersal and add to the ability of elephants as ecosystem engineers. We emphasize the importance of elephants as a key species in ecosystem dynamics and conservation practice.