The historical ecology of the large mammal populations of Ngorongoro Crater,Tanzania, east Africa

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Genetic diversity,population genetic structure and demographic history of Przewalski’s gazelle (<Emphasis Type="Italic">Procapra przewalskii</Emphasis>): implications for conservation

The Przewalski’s gazelle (Procapra przewalskii) is one of the most endangered antelope species in the world. It is endemic to China and is a flagship species in the eastern part of the Qinghai–Tibet plateau. To establish effective conservation measures on this species, genetic information such as genetic structure is needed. However, there has not been a comprehensive genetic assessment on this gazelle using nuclear DNA markers yet. Here, we employed 13 microsatellite loci to investigate genetic diversity, population genetic structure and demographic history of Przewalski’s gazelle using noninvasive samples of 169 wild gazelles collected from nine populations. A total of 76 alleles were detected from the entire samples, mean allele number was 5.85, and overall H _O and H _E were 0.525 and 0.552, respectively. Structure and GENELAND analyses found six genetic groups in the nine populations. Between the inferred genetic groups, significant genetic differentiation and low migration rates were detected. Demographic analyses indicated that Przewalski’s gazelle experienced genetic bottleneck and severe population decline, with the ancestral effective population size reducing to less than one percent. Based on the results of this study, we provide several conservation recommendations for Przewalski’s gazelle, such as six management units, periodic monitoring and special conservation consideration on the Qiejitan population.     

青藏公路对藏羚羊、藏原羚和藏野驴活动的影响

2003年8月和2004年8月,在可可西里国家自然保护区通过实地调查,分析了青藏公路运营对藏羚羊(Pantholops hodgsoni)、藏原羚(Procapra picticaudata)和藏野驴(Equus kiang)行为活动的影响.结果表明:藏野驴对青藏公路形成了回避,其在距路基1 001～2 000和2 001～3 000 m区域内的种群密度显著高于0～500 m的区域(P＜0.05);青藏公路对藏羚羊、藏原羚的行为活动产生了一定程度的干扰,尤其是对藏羚羊,其在距路基0～500 m区域内的行为活动与距路基2000 m之外的区域具有极显著差异(P＜0.01).同时,因其群体数量大,个体通过公路所花费的时间长,需要很长的车辆行驶间隔才能通过公路,故受车辆运输的干扰最大,无法顺利通过公路.研究还发现,在白天的不同时间段,藏羚羊、藏原羚在公路附近的数量分布与各时间段内的车流量呈极显著负相关,这有利于其穿越公路,说明野生动物通过自身的适应和行为调节可以减少环境改变所造成的影响.     

The ecological consequences of megafaunal loss: giant tortoises and wetland biodiversity

The giant tortoises of the Galápagos have become greatly depleted since European discovery of the islands in the 16th Century, with populations declining from an estimated 250 000 to between 8000 and 14 000 in the 1970s. Successful tortoise conservation efforts have focused on species recovery, but ecosystem conservation and restoration requires a better understanding of the wider ecological consequences of this drastic reduction in the archipelago's only large native herbivore. We report the first evidence from palaeoecological records of coprophilous fungal spores of the formerly more extensive geographical range of giant tortoises in the highlands of Santa Cruz Island. Upland tortoise populations on Santa Cruz declined 500–700 years ago, likely the result of human impact or possible climatic change. Former freshwater wetlands, a now limited habitat‐type, were found to have converted to Sphagnum bogs concomitant with tortoise loss, subsequently leading to the decline of several now‐rare or extinct plant species.     

When parks work: Effect of anthropogenic disturbance on occupancy of tropical forest mammals

Protected areas (PAs) in the tropics are vulnerable to human encroachment, and, despite formal protection, they do not fully mitigate anthropogenic threats to habitats and biodiversity. However, attempts to quantify the effectiveness of PAs and to understand the status and changes of wildlife populations in relation to protection efficiency remain limited. Here, we used camera‐trapping data collected over 8 consecutive years (2009–2016) to investigate the yearly occurrences of medium‐to‐large mammals within the Udzungwa Mountains National Park (Tanzania), an area of outstanding importance for biological endemism and conservation. Specifically, we evaluated the effects of habitat and proxies of human disturbance, namely illegal hunting with snares and firewood collection (a practice that was banned in 2011 in the park), on species' occurrence probabilities. Our results showed variability in species' responses to disturbance: The only species that showed a negative effect of the number of snares found on occurrence probability was the Harvey's duiker, a relatively widespread forest antelope. Similarly, we found a moderate positive effect of the firewood collection ban on only the suni, another common antelope, and a negative effect on a large opportunistic rodent, the giant‐pouched rat. Importantly, we found evidence of temporal stability in occurrence probability for all species over the 8‐year study period. Our findings suggest that well‐managed PAs can sustain mammal populations in tropical forests. However, variability among species in their responses to anthropogenic disturbance necessitates consideration in the design of conservation action plans for multiple taxa.     

Threatened woody flora as an ecological indicator of large herbivore introductions

Rewilding and translocations of large herbivores for conservation purposes have increased in recent times, with numerous introductions inside and outside their native range. This study aims to analyze the use of threatened plant taxa as a possible ecological indicator of large herbivore introductions. We examined the effects of a threatened large ungulate, the Barbary sheep (Ammotragus lervia), on both endangered and vulnerable woody taxa after its introduction in 1970. Contrary to our hypothesis, the herbivore impact on threatened woody species was higher than that found on widespread woody plants. The results reveal that 35.7% of the threatened species showed the highest possible level of herbivore damage in contrast to 6.5% for the widespread species. Threatened species were preferred over common plants, probably due to their greater palatability. Overall plant cover, including neighboring species, was also an important factor determining browsing damage and, thus, habitats with low ground cover should be particularly considered in conservation plans. Herbivore damage on common taxa should be taken with caution since they could mask unsustainable herbivore densities for threatened woody taxa or protected habitats. The use of threatened woody taxa through the studied ecological indicators (herbivore damage, plant preferences, habitat use and regeneration success) represented a useful tool to assess the sustainability of large herbivores introductions and to establish a priority conservation ranking for threatened plant species. These findings highlight the deleterious effects of overabundant ungulate populations regardless its origin (exotic or native) and the need of monitoring threatened woody taxa to better estimate the suitability and sustainability of large herbivore introductions.     

Food resource partitioning among large herbivores of eastern Mongolia in summer

The Mongolian gazelle (Procapra gutturosa Pallas, 1777) and five domestic herbivores share the steppe plants. The desertification of the steppe induced by overgrazing is related to the activities of the community of the large herbivore. A plant-herbivore data matrix obtained by cuticular analysis has made it possible to estimate the impact of trophic interaction in the dynamics of the herbivore comminity of the Mongolian steppe. By estimating pasture use, food niche overlap, and competition advantages of the studied species, it is concluded that the present population decline in the Mongolian gazelle resulted not only from overkill and artificial habitat fragmentation but also from composition, abundance, and spatial distribution of livestock species.     

Do local communities support the conservation of endangered Przewalski’s gazelle?

Understanding local attitudes and opinion is vital to the success of conservation programs, especially in areas of expanding human populations such as China. Przewalski’s gazelle (Procapra przewalskii) is an endangered ungulate found only in the eastern part of the Qinghai-Tibet Plateau. The gazelle is a conservation focus; however, little is known regarding how this animal is perceived by local people. To understand the relationship between demography, levels of conservation knowledge, and attitudes, we conducted 174 interviewer-led surveys in villages located inside, near, and away from the gazelle’s home ranges around Qinghai Lake, China. About half of the interviewees were aware of gazelle conservation. No more than half of the interviewees were aware that grassland fence, livestock, roads, and wolves negatively impact upon gazelle. On the whole, the majority of interviewees supported the conservation of gazelle. There were high levels of support for both establishing a special protected area and investing more funds in conservation but very few interviewees reported personal benefits from gazelle conservation. Overall attitude of interviewees toward the gazelle differed significantly among regions and people living near the range of gazelle were the most positive. Interviewees with conservation information were more positive than interviewees lacking such information. People who had more education or possessed more grassland had more positive attitudes toward the gazelle. This study suggests that greater communication is needed with local people. Programs that promote public engagement and participation are required for the conservation of Przewalski’s gazelle and other larger herbivores on the Qinghai-Tibet Plateau.     

Factors affecting the distribution of dorcas gazelle

The dorcas gazelle Gazella dorcas was very common and widespread in Tunisia. Nowadays, only some small isolated populations still survive in the desert areas of the southern part of the country. Factors affecting the distribution of this species in Tunisia have never been investigated despite the importance of such investigations for elaborating long-term conservation plans for the remaining wild populations. Using data on gazelle occurrence and on a set of habitat and human variables collected in south-eastern Tunisia, we aimed to identify the factors affecting gazelle distribution in this area. In particular, we investigated the relevance of habitat versus human factors for gazelle occurrence probability. As predicted, we found that human variables were the most relevant factors shaping the distribution patterns of gazelles in the studied area. Gazelles tended to avoid areas where agricultural development has occurred but did not seem to be disturbed by livestock. Overall, our results suggest that the occurrence probability of dorcas gazelle in southern Tunisia was mainly dependent on human presence and land use, rather than habitat characteristics. The recent intensification of agriculture in the more remote areas of southern Tunisia may thus constitute a serious threat to the conservation of this endangered species.     

Monitoring large herbivore diversity at different scales: comparing direct and indirect methods

Monitoring of large herbivores is central to research and management activities in many protected areas. Monitoring programs were originally developed to estimate (trends in) population sizes of individual species. However, emphasis is shifting increasingly towards conservation of diversity and communities instead of individual species, as a growing literature shows the importance of herbivore diversity for ecosystem functioning. We argue that the design of monitoring programs has not yet been adapted well to this new conservation paradigm. Using large herbivore census data from Hluhluwe-iMfolozi Park, South Africa, we studied how monitoring methodology (observational counts vs. dung counts) and spatial scale interact in influencing estimates of large herbivore species richness and diversity. Dung counts resulted in higher herbivore species richness and diversity estimates than direct observational counts, especially at finer monitoring resolutions (grid cells smaller than 25 km²). At monitoring resolutions coarser than 25 km² both methods gave comparable diversity estimates. The methods also yielded different spatial diversity estimates, especially at finer resolutions. Grid cells with high diversity according to the dung count data did not necessarily have high diversity according to the observational counts, as shown by low correlation of grid cell values of both methods. We discuss these results in the light of estimates of the sampling effort of each method and, hence, suggest new monitoring designs that are more suitable for tracking temporal and spatial trends in large herbivore diversity and community composition.     

青藏高原有蹄类动物多样性和特有性: 演化与保护

青藏高原是地球上一个独特的自然地理单元, 具有丰富的生境类型和生物种类, 是生物多样性与全球环境变化领域的热点研究区域。青藏高原发育着独特的动物区系, 尤其是有蹄类动物, 如藏羚(Pantholops hodgsonii)、野牦牛(Bos mutus)、藏原羚(Procapra picticaudata)、普氏原羚(P. przewalskii)、白唇鹿(Przewalskium albirostris)等青藏高原特有动物。在本文中, 我们探讨了如下问题: 青藏高原有多少种有蹄类动物?有多少种特有有蹄类动物?其分布格局如何?生存状况如何?保护现状如何?我们首先确定了青藏高原动物地理区的地理边界。发现青藏高原有28种有蹄类, 其中10种是青藏高原特有种。青藏高原有蹄类种数占中国有蹄类的42%, 单位面积上的有蹄类物种密度比中国现生有蹄类物种平均密度高62%。特有种比例高达36%。然而, 青藏高原有蹄类物种分布不均匀, 其丰富度呈东部高西部低格局, 而高原特有有蹄类则分布于高原腹地。青藏高原有蹄类动物生存受威胁比例高, 其中71%为受威胁物种, 54%被列入濒危野生动植物种国际贸易公约(CITES)附录I或附录II。野外调查发现大额牛(Bos frontalis)已经野外灭绝, 目前仅在高黎贡山有人工养殖的群体。青藏高原有蹄类物种红色名录指数从1998-2015年呈现持续下降趋势, 全球气候变化将加剧这一趋势。青藏高原有蹄类受威胁局面仍在继续, 物种生存状况持续恶化。虽然经过40年的自然保护区建设, 但一些青藏高原有蹄类的重要种群与栖息地并没有被自然保护区和新建的三江源国家公园所覆盖。因此, 在开发青藏高原、实现人类社会经济发展目标的同时, 应尽量保存高原野生动物种群与生境, 实现青藏高原草地生态系统的可持续利用与生物多样性保护的双赢目标。     

Unpredictability of vigilance in two sympatric Tibetan ungulates

Vigilance is important for anti-predation, and different animals adopt different vigilance strategies. Instantaneous and sequential randomness in vigilance behavior are two main principles for the classic Pulliam model (1973). Given this context, we studied the vigilance behaviors in two wild cloven-hoofed animals, the Tibetan antelope (Pantholops hodgsonii) and the Tibetan gazelle (Procapra picticaudata) on Qinghai–Tibet Plateau, to explore if the two randomness principles work across species. The results showed that the distribution of inter-scan intervals of both Tibetan antelope and Tibetan gazelle followed the negative exponential distribution; inter-scans of both Tibetan antelope and Tibetan gazelle were unrelated with their previous scan, and most sequences of inter-scan intervals could be considered as random organized or unpredictable. In conclusion, the vigilance patterns of Tibetan antelope and Tibetan gazelle followed instantaneous randomness and sequential randomness of Pulliam model. A random vigilance strategy might be the best choice for Tibetan ungulates, and how to distinguish the social vigilance from anti-predator vigilance is an important issue for future research.     

Long‐term persistence of wildlife populations in a pastoral area

Facilitating coexistence between people and wildlife is a major conservation challenge in East Africa. Some conservation models aim to balance the needs of people and wildlife, but the effectiveness of these models is rarely assessed. Using a case‐study approach, we assessed the ecological performance of a pastoral area in northern Tanzania (Manyara Ranch) and established a long‐term wildlife population monitoring program (carried out intermittently from 2003 to 2008 and regularly from 2011 to 2019) embedded in a distance sampling framework. By comparing density estimates of the road transect‐based long‐term monitoring to estimates derived from systematically distributed transects, we found that the bias associated with nonrandom placement of transects was nonsignificant. Overall, cattle and sheep and goat reached the greatest densities and several wildlife species occurred at densities similar (zebra, wildebeest, waterbuck, Kirk's dik‐dik) or possibly even greater (giraffe, eland, lesser kudu, Grant's gazelle, Thomson's gazelle) than in adjacent national parks in the same ecosystem. Generalized linear mixed models suggested that most wildlife species (8 out of 14) reached greatest densities during the dry season, that wildlife population densities either remained constant or increased over the 17‐year period, and that herbivorous livestock species remained constant, while domestic dog population decreased over time. Cross‐species correlations did not provide evidence for interference competition between grazing or mixed livestock species and wildlife species but indicate possible negative relationships between domestic dog and warthog populations. Overall, wildlife and livestock populations in Manyara Ranch appear to coexist over the 17‐year span. Most likely, this is facilitated by existing connectivity to adjacent protected areas, effective anti‐poaching efforts, spatio‐temporal grazing restrictions, favorable environmental conditions of the ranch, and spatial heterogeneity of surface water and habitats. This long‐term case study illustrates the potential of rangelands to simultaneously support wildlife conservation and human livelihood goals if livestock grazing is restricted in space, time, and numbers.     

社区对普氏原羚的保护态度和意愿及其影响因素

普氏原羚(Procapra przewalskii)是我国的特有种,青海湖地区是其唯一的分布区,青海湖国家级自然保护区对普氏原羚的有效保护、社区发展与保护之间矛盾的协调,对于生物多样性保护具有重要意义。了解青海湖国家级自然保护区周边社区对普氏原羚的保护态度、意愿及其影响因素,可以为自然保护区开展生物多样性保护工作,维持当地生态和平发展提供保障。基于问卷调查法对自然保护区周边社区的牧民和居民进行了调查,研究表明:(1)受访者认为草场质量退化(n=92,65.25%)和草场围栏设置(n=80,56.74%)是威胁普氏原羚的主要因素;在以保护普氏原羚和给予生态补偿为前提下,牧民拆除围栏的意愿有所提高(由20.78%分别提高至34.21%和40.79%);(2)管理部门的宣教活动(79.43%)、手机(31.91%)和电视(28.37%)等媒体报道是受访者了解野生动物保护相关政策法规的主要渠道,可以增进受访者对政策法规的了解,积极影响受访者对普氏原羚的认知(P < 0.01)、保护态度(P < 0.01)和保护意愿(P < 0.01);(3)受访者一致认为自然保护区的严格管理与保护(牧民94.81%,居民96.87%)、当地牧民对普氏原羚的包容与保护(牧民97.40%,居民87.50%)是普氏原羚能够在自然保护区周边生存的主要原因;(4)受访者对普氏原羚的保护态度和意愿均较高,且愿意参与宣传教育(92.91%)和社区共管(87.94%)工作;(5)除了受访者的文化程度、年龄、宗教信仰和家庭年收入的影响,对政策法规的了解及拆除围栏认同度是影响受访者对普氏原羚保护态度和意愿的关键因素(P < 0.01)。因此,建议自然保护区以国家公园建设为契机,加强协调保护与发展的科学研究,深入开展宣传教育,增进社区对自然保护区生物多样性的认识,提升社区共管参与度。     

Dynamics of ungulates in relation to climatic and land use changes in an insularized African savanna ecosystem

Land use change and human population growth are accelerating the fragmentation and insularization of wildlife habitats worldwide. The conservation and management of wildlife in the resultant ‘island’ ecosystems in the context of global warming is challenging due to the isolation and reduced size of the ecosystems and hence the scale over which ecosystem processes can operate. We analyzed trends in numbers of nine large herbivores in Kenya’s Lake Nakuru National Park to understand how rainfall and temperature variability, surrounding land use changes, and boundary fencing affected wildlife population dynamics inside the park during 1970–2011. Buffalo, zebra and Thomson’s gazelle numbers increased persistently. Grant’s gazelle and impala increased initially then gradually declined. Waterbuck and warthog numbers progressively declined to levels that potentially threatened their local population persistence. The total biomass of ungulates tripled from 1970 to 2011, with buffalo replacing waterbuck as the predominant species in biomass. Increased competition from buffalo and zebra, heightened predation and illicit human harvests probably all contributed to the declines by waterbuck and warthog. Density-dependent limitation of population growth within the park confines was evident for buffalo, impala, eland, giraffe, Grant’s and Thomson’s gazelles. Fluctuations in the lake level related to varying rainfall affected changes in animal abundance through expansion of the lake area and flooding of grasslands bordering the lake. Unusually, the most stressful conditions were associated with high water levels following high rainfall. There was also evidence of carry-over effects from prior habitat conditions affecting all species. The relatively stable populations of all species except warthog and waterbuck demonstrate the remarkable capacity of this small, insularized park to retain viable populations of most of the large herbivores, without much management intervention.     

Effect of anthropogenic landscape features on population genetic differentiation of Przewalski's gazelle: main role of human settlement

Anthropogenic landscapes influence evolutionary processes such as population genetic differentiation, however, not every type of landscape features exert the same effect on a species, hence it is necessary to estimate their relative effect for species management and conservation. Przewalski's gazelle (Procapra przewalskii), which inhabits a human-altered area on Qinghai-Tibet Plateau, is one of the most endangered antelope species in the world. Here, we report a landscape genetic study on Przewalski's gazelle. We used skin and fecal samples of 169 wild gazelles collected from nine populations and thirteen microsatellite markers to assess the genetic effect of anthropogenic landscape features on this species. For comparison, the genetic effect of geographical distance and topography were also evaluated. We found significant genetic differentiation, six genetic groups and restricted dispersal pattern in Przewalski's gazelle. Topography, human settlement and road appear to be responsible for observed genetic differentiation as they were significantly correlated with both genetic distance measures [F(ST)/(1-F(ST)) and F'(ST)/(1-F'(ST))] in Mantel tests. IBD (isolation by distance) was also inferred as a significant factor in Mantel tests when genetic distance was measured as F(ST)/(1-F(ST)). However, using partial Mantel tests, AIC(c) calculations, causal modeling and AMOVA analysis, we found that human settlement was the main factor shaping current genetic differentiation among those tested. Altogether, our results reveal the relative influence of geographical distance, topography and three anthropogenic landscape-type on population genetic differentiation of Przewalski's gazelle and provide useful information for conservation measures on this endangered species.     

Resource partitioning between ungulate populations in arid environments

Herbivores are major drivers of ecosystem structure, diversity, and function. Resilient ecosystems therefore require viable herbivore populations in a sustainable balance with environmental resource availability. This balance is becoming harder to achieve, with increasingly threatened species reliant on small protected areas in increasingly harsh and unpredictable environments. Arid environments in North Africa exemplify this situation, featuring a biologically distinct species assemblage exposed to extreme and volatile conditions, including habitat loss and climate change‐associated threats. Here, we implement an integrated likelihood approach to relate scimitar‐horned oryx (Oryx dammah) and dorcas gazelle (Gazella dorcas) density, via dung distance sampling, to habitat, predator, and geographic correlates in Dghoumes National Park, Tunisia. We show how two threatened sympatric ungulates partition resources on the habitat axis, exhibiting nonuniform responses to the same vegetation gradient. Scimitar‐horned oryx were positively associated with plant species richness, selecting for vegetated ephemeral watercourses (wadis) dominated by herbaceous cover. Conversely, dorcas gazelle were negatively associated with vegetation density (herbaceous height, litter cover, and herbaceous cover), selecting instead for rocky plains with sparse vegetation. We suggest that adequate plant species richness should be a prerequisite for areas proposed for future ungulate reintroductions in arid and semi‐arid environments. This evidence will inform adaptive management of reintroduced ungulates in protected environments, helping managers and planners design sustainable ecosystems and effective conservation programs.     

有机无机肥配施提高麦-稻轮作系统中水稻氮肥利用率的机制

采用盆栽试验,研究了有机无机肥配施对麦-稻轮作系统中水稻氮素累积动态和土壤氮素供应动态的影响,并从微生物学角度探讨了有机无机肥协同提高水稻氮肥利用率的机制.结果表明：有机无机肥配施处理的土壤微生物生物量碳、氮和矿质态氮在水稻分蘖期前低于化肥处理,而在抽穗期至灌浆期显著高于其他处理.土壤氮素供应动态与水稻吸收利用氮素规律吻合程度最高,促进了水稻产量、生物量和氮素累积量的增加,显著提高了水稻的氮肥利用率.其主要机制是有机无机肥配施促进了土壤微生物繁殖,使其在水稻生育前期固持了较多的矿质氮,在水稻生育中、后期这些氮素逐渐被释放以供水稻吸收利用,较好地满足了水稻各阶段生长发育对氮素养分的需求.     

大型食草动物的聚群规则:印度西部热带干旱森林中有蹄类动物局域和区域尺度的多样性格局

竞争能够塑造自然群落并由其给出可用备择模型检验的一般性聚集规则。关于多种动物集合的竞争结构证据至今还非常少见,我们给出了一个备择模型分析用于检验印度西部热带干旱森林中当地5种大型食草类动物(花鹿Axisaxis,印度大蓝羚Boselaphustragocamelus,水鹿Cervusunicolor,印度瞪羚Gazellabennetti,野猪Susscrofa)是否符合一般性集合规则。使用蒙特卡罗模拟分析了动物的生态位重叠和身体大小比率的类似性,结果表明当地这些种的集合不是竞争结构决定的,其内部阶元结构处于亚最适种丰富度。另外2种有蹄类(印度黑羚Antilopecervicapra,四角羚羊Tetracerusquadricornis)属于地域性种库的组成部分,但缺失于这种集合;身体大小组合在地域性物种集合中不是随机的,然而在当地集合中能够通过随机性机会获得。对于观察到的类型,我们认为由于灭绝留下的统计学空缺似乎最能解释现存集合。由于天敌(大型食肉类)能够减少猎物物种的种间竞争,使得这种无规则生态位配置具有成立的可能性。由于对四角羚羊(T.quadricornis)的生物学和保护现状知之甚少,未将该种包括在该聚集中。我认为对这类较少被人类了解的物种其保护问题被忽视了,今后获得这些稀少的地方特有物种的生态学资料是一项紧急课题.     

Key factors and related principles in the conservation of large African carnivores

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