Different factors that modify anti-predator behaviour in guanacos (Lama guanicoe)

Animals optimize the trade-off between the cost of not fleeing and the benefits of staying because the factors that influence flight decisions and the disturbance level of a particular stimulus can vary both spatially and temporally. Different factors (human impact and habitat characteristics) likely to modify anti-predator behaviour in different types of guanaco social groups were analysed. We found that group size was conditioned by high poaching, vehicle traffic, predation risk and vegetation density. Solitary adult males showed shorter alert and flight initiation distances than bachelor and mixed groups. Alert distance was greater during the summer season, and assessment times were shorter when young were present in the groups. In high-predation-risk environments, guanacos detected threats at greater distances and flight initiation distance was longer. Alert distances were shorter on steeper sloped hills and assessment times were shorter in areas with irregular topography than on flat sites. In high traffic areas, flight initiation distance was longer and assessment times were shorter. And in areas with low poaching intensity, assessment times were greater than in those with high poaching levels. Therefore, guanacos may be able to evaluate a true threat. Social group and anti-predator responses were conditioned by habitat characteristics and human impact. We consider that plasticity of responses could be key to the survival of guanacos.     

Cooperative vigilance: the guanaco's (Lama guanicoe) key antipredator mechanism

The concept of sociality has been associated with the effectiveness of antipredator mechanisms, like cooperative vigilance and the dilution effect. Lama guanicoe (guanaco) is a social native herbivore in South America and a social species. The objectives of this study were to evaluate the antipredator responses of different-sized groups of guanacos in areas with varying predation risks and to determine antipredator mechanisms in guanacos. For this, we measured different antipredator responses to a potential predator (human subjects). Detection of predator and flight distances from predator both increased with a greater number of guanacos per group and with greater distances among guanacos within the social group. Both buffer distance and flight time decreased with a greater number of guanacos per group, but increased with greater distances among guanacos inside the social group. Solitary adult males moved shorter distance and mixed groups moved greater distances. Flight distances were greater in areas with tall and dense vegetation than in areas with low vegetation. Buffer distance and flight time were shorter in undulating land than on flat lands, and groups were usually observed on hill slopes. Our results suggest that the benefit of social grouping in guanacos is the increased probability of avoiding predator with cooperative vigilance and not with the dilution effect. This means that a predator could be detected earlier when approaching a guanaco group than when approaching a solitary individuals and could thus be avoided.     

Habitat use and preference by guanacos,vicuñas,and livestock in an altitudinal gradient in northwest Argentina

Distribution of ungulates is regulated by natural factors, such as presence of other species, climate, and habitat variability, as well as human activities, including livestock grazing and mining. Understanding the spatial dynamics of landscape use can help solve problems of access to key resources by native herbivores. Laguna Brava Reserve is a protected area of Argentina where the two wild South American camelids, guanacos and vicuñas, coexist with cattle, mules, horses, and goats. Information about the effects of livestock and mining activities, which are widespread throughout the region, on wild camelids is scarce. We used variable-width transects to determine the distribution of guanacos, vicuñas, equids, and cattle in relation to five habitat types defined according to vegetation and topography in the reserve. We carried out a correspondence analysis between the proportion of groups observed in and the proportion of area occupied by each habitat, and a χ ² goodness of fit test to establish if camelids and livestock selected a particular habitat type. Vicuñas were associated with grasslands at high altitudes while guanacos and livestock were associated with shrublands at lower elevations. This coevolutionary segregation between guanacos and vicuñas possibly reduced competition between the two species. Competition between camelids and livestock is probably low because of the low density of livestock. Vegas were preferred by all species year round but used more intensively in summer. In order to conserve the wild camelids of the region, governments must implement measures to conserve the critical habitat provided by the vegas.     

Altitudinal effects on habitat selection of dung beetles (Scarabaeoidea: Aphodiidae) in the northern Iberian peninsula

The effects or vegetation cover on the abundance and species richness of dung beetles (Aphodiidae) were examined in three altitudinal zones: lowland (520–600 m), mid-altitude (950–963 m) and highland (1230–1275 m). Pitfall traps baited with fresh cattle dung were placed in three vegetation types at each altitudinal zone: forest, heathland and pasture. Species richness was lower in forests than in the other vegetation types. The total abundance of beetles also varied with vegetation type, but the effect was dependent on altitude. Number of individuals was higher in pasture at highlands and in heathland and forest at mid-altitude and lowlands. An altitudinal dependence of distribution of individuals between vegetation types was also found for the more abundant species in the study area. These results could be explained if the local distribution of individuals between vegetation types was determined by microcli-matic factors, mainly temperature. Differences in altitude between sites are associated with temperature changes, determining the habitat selection of species at each altitude.     

A report on the conservation status of south Indian plants

Data on the conservation status of 167 species of flowering plants presented here are from two representative sectors in south India: (a) the lowlands, characterized by dry deciduous vegetation representative of the Deccan plateau, as also a cluster of eight low altitude hill ranges [to 1200 (1500) m] of the southernmost reaches of the Eastern Ghats of India, and coastlands including mangroves; and (b) the hills, the high altitude hill ranges (to 2475 m) of the Palni hills, an eastward spur of the Western Ghats of India, characterized by evergreen vegetation but largely decimated around the hill station of Kodaikanal with the invasion of alien species since the l840s with the arrival of overseas colonial personnel and the raising of commercial monoculture plantations. Data for the 167 species are entered in 7 + 1 columns for the two regions separately. However, the IUCN red list categories are not used in their entirety for two reasons: (i) the areas are relatively small; (ii) the stress comes more from extrinsic causes like habitat destruction and over-exploitation rather than intrinsic (genetic) causes. However, it is stressed that what is happening over restricted areas over short time intervals is a miniature of what is happening over larger areas over longer periods, and hence these data are vitally important in planning for conservation and eco-restoration. The quality and quantity of new information are decisive; the findings are discussed under nine heads, as the first synthesis of results obtained from over two decades of field work.     

Home Range Size and Habitat use by Cat Ba Langurs (<Emphasis Type="Italic">Trachypithecus poliocephalus</Emphasis>) in a Disturbed and Fragmented Habitat

Primate home range size and habitat use are affected by resource availability, which may change seasonally. Limestone langurs (Trachypithecus genus), including the Critically Endangered Cat Ba langur (Trachypithecus poliocephalus), live on limestone karst hills with shrubby and discontinuous vegetation. This study explores home range size and habitat use in relation to substrate, vegetation coverage, and hill type for Cat Ba langurs living on Cat Ba Island. We predicted that home range size would be similar to that of other limestone langurs and that as resources vary seasonally and across habitat types, habitat use would vary with season and behavior, with foraging concentrated on slopes, where food is plentiful. We collected 180 days of observational data on two reproductive groups (N?=?7 and N?=?10–13), taking GPS fixes of the group whenever they moved farther than the typical group spread to determine home ranges, and 10-min instantaneous scans to assess habitat use. The two groups had home ranges of 22 ha and 50 ha (0.32 and 0.20–0.26 individuals/ha respectively). Ranges for both groups were smaller in the dry season than the wet season, although we could not assess seasonal variation statistically. The langurs spent most scans on rocks, in sparsely vegetated areas, and on exposed slopes and steep cliffs; however they foraged primarily on gradually inclined slopes, especially in the dry season. These results suggest that conservation efforts should focus on protecting nutritionally important valleys and exposed slopes to ensure year-long access to food resources. It may, however, be difficult to balance human and nonhuman primate habitat use.     

How dung beetles respond to a human‐modified variegated landscape in Mexican cloud forest: a study of biodiversity integrating ecological and biogeographical perspectives

Aim To analyse how the dung beetles (Scarabaeinae) respond to a modified, variegated landscape, taking into account the biogeographical peculiarities of the Mexican Transition Zone. Location This study covers cloud forest (CF) of the Sierra Norte de Puebla mountain range and part of the Sierra Madre Oriental mountain range (Mexico). Methods We applied proportional sampling based on the landscape variegation model with Scarabaeinae as the indicator group, and using two approaches: structural units (vegetation type) and spatial units (windows). We used two measures – richness and Shannon diversity – and applied multiplicative diversity partitioning to obtain independent alpha and beta diversities for the landscape, windows and vegetation types. We grouped species by biogeographical distribution pattern for the biogeographical analysis and by whether they were originally from CF. Results The transformation of CF into secondary forest, pastures and other types of vegetation increases the Scarabaeinae diversity of the landscape, in vegetation types and windows. This increase is the result of species arriving from the tropical lowlands. However, the original dung beetle community of the CF dominates at different scales in the number of species, abundance and biomass. With increasing habitat modification, beta diversity increases in the windows, and species with the Tropical Palaeoamerican distribution pattern increase in abundance in vegetation types and windows. Main conclusions The variegated character of the landscape explains well the distribution and diversity of this dung beetle community. The peculiar characteristics of the Mexican Transition Zone have an effect owing to the overlap of fauna with different biogeographical origins. The conversion of fragmented landscapes to variegated landscapes could be a conservation goal in human‐modified mountain landscapes. Sampling proportional to the area of different types of vegetation and the use of windows offer an alternative experimental design in variegated landscapes.     

Mexican Jay social group size varies with habitat in northeastern Mexico

ABSTRACT.   We evaluated the hypothesis that social group size in Mexican Jays ( Aphelocoma ultramarina ) varies with habitat structure. We counted the social group size of Mexican Jays over a range of elevations and forest types in a single mountain range in northern Mexico (Sierra El Carmen, Coahuila). Group size increased significantly with elevation, in contrast to a population of Mexican Jays in Arizona that showed no such trend in another study. Among the vegetation variables measured, those relating to size of pines and oaks were especially important in explaining variation in group size. Because acorns and pine nuts are a major part of the diet of Mexican Jays, sites with larger oaks and pines may produce larger nut crops and support larger groups of jays. Elevation did not significantly explain variance in group size after taking vegetation into account. We compared group size and habitat variation across different parts of the geographic range of Mexican Jays. Our analysis indicates that variation of social group size in Mexican Jays is influenced by habitat quality at both local and geographic scales. Detailed studies on habitat structure and demographics of this population are needed to further clarify aspects of habitat quality important to these jays, and the mechanisms by which variation in social structure is maintained.     

三峡库区澎溪河消落带植物群落分布格局及生境影响

三峡消落带是一条特殊的水—陆交错带,其生境的特殊性及对整个三峡库区的影响逐渐成为地学、环境科学、生态学等学科的研究热点。植被是消落带各项生态功能的载体。然而,三峡水库的运行使消落带原有植被遭到破坏。通过对澎溪河消落带植物群落及其生境的实地调查,采用双向指示种法(TWINSPAN)划分植物群落类型,并结合方差分解和CCA排序法研究4类生境影响因素组14个生境影响因子与植物群落空间分布的关系,探讨生境对消落带植物群落组成、结构及多样性的影响。结果表明:(1)消落带植物群落包括5种类型:狗牙根+雀稗群落、狗尾草+狗牙根群落、黄荆群落、白茅+鬼针草群落、苔草群落;(2)CCA排序中,第1排序轴对消落带植被空间变化的累计解释量为6.83%,占生境条件总解释量的44.73%,能很好地解释消落带植物群落与生境的相互关系,植物群落类型沿排序轴呈梯度分布;(3)土壤是影响消落带植被空间分布格局的主要影响因素组,各影响因素组间交互作用明显。淹水时间、海拔、土壤含水量是植物群落空间分布的主要影响因子,解释量分别为5.3%、3.0%、2.9%;(4)4类影响因素组共解释消落带植物群落空间格局变化的14.6%,未解释部分所占比例较大,可能是由于消落带内生境条件复杂,影响其群落组成及空间分布的潜在因素较多,如各种土地利用政策、人类活动干扰及景观组成等因素也可能对消落带植物群落构成有影响。研究消落带植物空间分布及其与生境的关系,以期为科学认识消落带、保护水库环境提供依据。     

Habitat Selection and Post-Release Movement of Reintroduced Brown Treecreeper Individuals in Restored Temperate Woodland

It is essential to choose suitable habitat when reintroducing a species into its former range. Habitat quality may influence an individual’s dispersal decisions and also ultimately where they choose to settle. We examined whether variation in habitat quality (quantified by the level of ground vegetation cover and the installation of nest boxes) influenced the movement, habitat choice and survival of a reintroduced bird species. We experimentally reintroduced seven social groups (43 individuals) of the brown treecreeper (Climacteris picumnus) into two nature reserves in south-eastern Australia. We radio-tracked 18 brown treecreepers from release in November 2009 until February 2010. We observed extensive movements by individuals irrespective of the release environment or an individual’s gender. This indicated that individuals were capable of dispersing and actively selecting optimum habitat. This may alleviate pressure on wildlife planners to accurately select the most optimum release sites, so long as the species’ requirements are met. There was significant variation in movement between social groups, suggesting that social factors may be a more important influence on movement than habitat characteristics. We found a significant effect of ground vegetation cover on the likelihood of settlement by social groups, with high rates of settlement and survival in dry forests, rather than woodland (where the species typically resides), which has implications for the success of woodland restoration. However, overall the effects of variation in habitat quality were not as strong as we had expected, and resulted in some unpredicted effects such as low survival and settlement in woodland areas with medium levels of ground vegetation cover. The extensive movement by individuals and unforeseen effects of habitat characteristics make it difficult to predict the outcome of reintroductions, the movement behaviour and habitat selection of reintroduced individuals, particularly when based on current knowledge of a species’ ecology.     

喀斯特城市地表水热通量的时空变化研究

针对我国西南地区桂林喀斯特城市近20多年来快速扩展所引发的热环境问题,改进METRIC模型使其适用于喀斯特城市实际状况,利用模型和1994—2015年5景Landsat遥感图像反演地表水热通量,分析通量时空变化规律。结果表明,潜热通量从高到低依次为水体、喀斯特山峰阳坡植被、地面植被、喀斯特山峰阴坡植被、建筑/道路和裸土、喀斯特山峰裸岩,显热通量从高到低依次为喀斯特山峰裸岩和建筑/道路、裸土、喀斯特山峰阳坡植被、地面植被、喀斯特山峰阴坡植被、水体。水热通量随时间的变化受地表覆盖变化的影响,研究区波文比(显热通量与潜热通量比值)在1994年最高,达到1.62,2000年下降到1.24,之后逐渐升高至2015年的1.51。城市扩展过程出现的显热高值区和潜热低值区比例低于10%,其变化引发显热中低值区和潜热中高值区比例的变化,显热高值区最高比例在1994年(10.0%),2000年下降到5.4%,之后至2010年逐渐上升到9.4%,但2015年下降到7.1%,潜热低值区比例的变化趋势与显热高值区比例基本相同。植被覆盖度(Vegetation fraction,Pv)在0.1—0.8范围时对水热通量的影响相对更显著,Pv增加0.1,显热通量降低8—27 W/m~2,而潜热通量升高8—24 W/m~2。喀斯特山峰植被保护和城区地面绿化建设对喀斯特城市热环境的改善至关重要。     

白头叶猴栖息环境与栖息地选择的研究

通过样方法和焦点动物法分别对白头叶猴栖息环境进行了观察,并对栖息环境的植物多样性进行了统计分析。结果表明,白头叶猴栖息地可分为山脚、山腰、山顶和山弄平地4部分,各部分优势种植物不同,白头叶猴栖息地的Shannon Venner多样性指数为6.152,均匀度为0.8439,白头叶猴对石山山脚、山腰、山顶和山弄平地的利用率分布为66.45 5.65%,21.15±5.49%,12.78±6.8%。在山脚主要是休息和觅食,在山腰主要是移动,在山顶主要是冬季晒太阳。因此,保护白头叶猴的栖息地对保护白头叶猴有特别重要的意义。     

Social foraging and habitat use by a long-distance passerine migrant, Whinchat Saxicola rubetra, at a spring stopover site on the SE Adriatic coast

The preference for foraging in groups and the effect of physiognomic factors of a habitat on its use by foraging Whinchats (Saxicola rubetra) was studied during spring migration stopover in a mosaic cultural landscape at the SE Adriatic coast. Every record of spatially distinct Whinchats, either a solitary individual or a group, was referred to as a Whinchat unit. The units were classified as intensively foraging, less intensively foraging or non-foraging and divided into four size classes. The effect of physiognomic habitat factors on use of habitat by foraging Whinchat units was modelled. All possible additive models using logit link function were constructed from five independent physiognomic variables: (1) natural perches (NP), (2) artificial perches (AP), (3) high herbal vegetation (HHV), (4) open bushes (OB) and (5) heterogeneity of vegetation types (HVT). Variables HHV and OB were included simultaneously in the models. Models that were substantially supported by the data were selected according to second order Akaike’s information criterion AIC_c. Two such models contained variable(s) (1) NP and (2) NP + AP. The relative importance weights of physiognomic variables NP, AP, HVT, HHV and OB were 1, 0.38, 0.24, 0.13 and 0.13, respectively. Perches were thus the most important physiognomic habitat factor affecting habitat use by Whinchats in a mosaic cultural landscape. The great majority of Whinchats foraged in groups and the proportion of intensively foraging Whinchat units increased with unit size, leading to the conclusion that Whinchats preferred social to solitary foraging on the spring stopover at the SE Adriatic coast.     

半干旱地区煤矸石山生态分类研究

半干旱地区煤矸石山生态分类研究张军,杨芳,林华（辽宁省阜新矿务局林业处,１２３００３）ＥｃｏｌｏｇｉｃａｌＣｌａｓｓｉｆｉｃａｔｉｏｎｏｆＣｏａｌＧａｎｇｕｅＨｉｌｌｓｉｎＳｅｍｉ－ＡｒｉｄＲｅｇｉｏｎｓ．￥ＺｈａｎｇＪｕｎ;ＹａｎｇＦａｎｇ;Ｌｉｎ...     

Group size, spatial segregation and activity of wild sympatric vicuñas Vicugna vicugna and guanacos Lama guanicöe

Group size, activity and spatial segregation of sympatric guanacos and vicuñas have been investigated in the wild in the Catamarca Andes, Argentina. A total of 65 groups of vicuñas and 32 of guanacos was sighted. The size of vicuña and guanaco groups (mean ± SD: 4.8 ± 4.5 individuals and 3.5 ± 3.6 individuals respectively) fell within the range reported by other studies. The occurrence of solitary guanacos was unusually high. Spatial overlap between vicuñas and guanacos was wide and occurred from 4000 to 4200 m altitude. Possibly, the two species attained segregation through the use of areas differing in slope gradient. Most guanacos and vicuñas were foraging when spotted. The proportions of individuals engaged in foraging, resting and walking were, however, different between the two species, the percentage of guanacos grazing (94%) being particularly high in comparison with vicuñas (69%). Vicuña activity pattern varied throughout the day. They were on the move mainly just after midday and rested mainly late in the afternoon. Guanaco group size and pattern of activity showed more variations from other studies than those of vicuña. These differences may be related to the high altitude. In such an area, which lies at the upper limit of their altitudinal range, guanacos may have problems in meeting their energy demands, which are higher than those of vicuñas. Competition between the two species may occur in sympatric areas.     

Low habitat overlap at landscape scale between wild camelids and feral donkeys in the Chilean desert

Feral domestic ungulates may compete with the populations of wild herbivores with which they coexist, particularly so in arid regions. The potential competition between wild camelids and feral donkeys at the eastern sector of the Atacama Desert is evaluated in terms of their coincidence or segregation in habitat use and complemented with a comparison of reproductive output (yearling/adult ratio) of vicuña family groups in the proximity vs. distant from donkey observations. Habitat use of wild camelids and donkeys was sampled driving some 1250 km of roads and tracks at the dry and wet seasons. There were 221 vicuñas (Vicugna vicugna) sightings, 77 for donkeys (Equus asinus), 25 for guanacos (Lama guanicoe) and 8 for hybrids between guanacos and domestic llamas (Lama glama), as well as 174 randomly selected control locations. By means of Generalised Discriminant Analysis and Analysis of Variance we show that all ungulates actively select their habitat, with significant differences between use and availability in the area. Donkeys are relatively abundant in comparison with camelids and coincide broadly with both of them across the altitudinal gradient, but they fall between them in local scale habitat selection and do not seem to force their displacement from their preferred habitats. Thus donkeys occur preferentially on slopes with a high cover of tall shrubs, whereas vicuñas use valley bottoms with grass and guanacos the upper slope zones with grass. The potential for competition between donkeys and wild camelids is thus limited and it does not affect the reproductive output of vicuña in this region. Therefore, with the present knowledge we suggest that population control is not currently merited for feral donkeys.     

Impact of vegetation removal on the temperature and moisture content of red wood ant nests

We studied the influence of vegetation growing on red wood ant, Formica polyctena, hills and its removal, by cutting, on the temperature and moisture content of the nests. Vegetation was removed from half of nests (n = 10) in June and August. Generally, ant hills were small (0.1–1.1 m³) and their daily temperature fluctuations and moisture (16–38%) were low. The centre temperature of ant hills was positively correlated with ambient air temperature. Daily temperatures peaked at 13:00 and slowly decreased until 09:00 then increased again until 13:00. Nest moisture content was not related to nest volume. All the ant hills were covered with Reed Grass (Calamagrostis arundinacea) that grows through nests and reaches about 185–1085 g/dcm² of dry matter. Dry vegetation matter (g/dcm² of anthill surface) was the same on cut and uncut nests as well because all ant hills were under long-term management (vegetation removal) for at least 10 years. Although vegetation removal did not result in an immediate increase in the temperature of denuded ant hills removal did results in higher daily and night temperatures during the July-September period. The moisture content of nests with undisturbed and intact vegetation was the same. The dry matter content of vegetation strongly affected their moisture content. However, temperature at the inside centre of nests decreased as vegetation dry matter increased, i.e. there was a statistically negative correlation between temperature and moisture. The results support removing grass as a suitable management tool to facilitate the survival of wood ants. Received 30 December 2007; revised 22 April 2008; accepted 10 June 2008.     

How does size and isolation affect patches of steppe-like vegetation on slumping hills in Transylvania,Romania?

The region of Southern Transylvania in Romania contains large expanses of species-rich grassland and mixed farmland. Within these landscapes, clusters of small, steep-sided slumping hills support mosaics of herbaceous vegetation caused by the heterogeneity in temperature and water supply and maintained by mowing or grazing. These are of conservation interest not only for the high species density, but also the relict steppe-like vegetation types especially found on their south-facing slopes. Usually surrounded by more intensively used mesic grassland, these hills can be considered patches of species-rich grassland vegetation. We therefore surveyed the vascular plants in 10 m² plots on the south- and north-facing slopes of 50 hills in 12 clusters in order to investigate the influence of their size and isolation on the species richness and composition of the vegetation. We found that larger hills had higher plot-scale species richness, a greater proportion of competitive species and a lower proportion of species of steppe-like vegetation, but only on their south-facing slopes where the conditions are more extreme. Both large and small hills should be considered as important habitats and potential sources of propagules for plant communities in the surrounding areas.     

Reconstructed natural versus potential natural vegetation in vegetation mapping - a discussion of concepts

Reconstruction mapping of the natural (primary) vegetation of intensively cultivated land is based on: (1) classification of actually existing remains of natural or near-natural plant communities as mapping units; (2) delimitation of their habitat types; (3) detection of correlations between vegetation units and habitat types. Natural plant communities thus serve as indicators of abiotic habitat conditions. Reconstruction mapping is based on the extrapolation of the potential distribution of individual vegetation units to sites of similar habitat types where the natural vegetation does not exist any more. The same procedure is used for mapping the potential natural vegetation. Both types of natural vegetation maps are identical on sites where the abiotic natural habitat conditions (relief, geological substratum, climate, water regime, soils) remain practically unchanged. On sites where the natural habitat conditions have been considerably changed by man, e.g. in areas with superficial coal mining (complete destruction of the landscape, removal of soil cover, creation of large slag heaps) or in towns, no natural (primary) vegetation exists. This causes difficulties in the hypothetical concept of the potential natural vegetation and its definition. In contrast, in such sites reconstruction vegetation mapping uses the extrapolation of mapping units of the primary vegetation to the original natural habitat conditions.     

Are Limestone Hills a Refuge or Essential Habitat for White-Headed Langurs in Fusui,China?

We studied the ecology of white-headed langurs (Trachypithecus leucocephalus) in Fusui Precious Animal Reserve, Guangxi, China, in 1997/1998 and conducted surveys of them in 1996–1997 and 2003. We collected data on vegetation fragments and the activities of white-headed langurs at different levels on limestone hills. The langurs selected less fragmented habitats with less human disturbance. They spent ca. 60% of the day at lower levels of the hills during maintenance activities, including feeding. When humans were absent, the langurs even came to the ground. The hills themselves were used as a refuge from human disturbance but were not otherwise essential habitat. Results of this study have implications for improving conservation management for the langurs.