Farmland habitat selection of wintering lesser kestrels in a Spanish pseudosteppe: implications for conservation strategies

The lesser kestrel Falco naumanni is a globally threatened species, whose breeding populations seem to have declined due to recent agricultural changes. However, nothing is known about habitat requirements during winter, despite the fact that several populations are overwintering in areas affected by agricultural transformations. We studied population size and habitat selection by wintering lesser kestrels in a Spanish pseudosteppe (Los Monegros), where traditional fallow systems for cereals are rapidly being replaced by intensive and/or irrigated crops. About 15% of the adult population wintered in the study area, as determined by systematic roadside counts compared with accurate censuses made during the breeding season. Wintering lesser kestrels preferred to forage on field margins and stubble, while avoiding abandoned fields, ploughs, scrubland, growing cereals and, mainly, the expanding irrigated crops. This work confirms the need to incorporate the habitat requirements of threatened species over their complete annual cycles; while breeding lesser kestrels scarcely use fallow (ploughed at that time), during the winter, fallow (stubble at that time) is their main foraging habitat. Both fallow land and the present agricultural calendar should be maintained to assure the conservation of wintering lesser kestrel populations.     

Influences of seasons and dietary composition on diurnal raptor habitat use in Chembe Bird Sanctuary,Zambia: Implications for conservation

Diurnal raptor habitat use has conservation implications due to environmental and anthropogenic interactions. Three tree-nesting diurnal raptors, black kites (Milvus milvus), steppe buzzards (Buteo vulpinus) and African fish eagles (Haliaeetus vocifer), were studied from December 2016 to October 2017. The objective was to determine factors influencing diurnal raptor habitat selection and use in and around Chembe Bird Sanctuary of Kalulushi district, Zambia. We surveyed for birds in ten randomly selected 200 × 200 m sample plots in each of the five stratified sampling units (miombo woodland, grasslands, human settlements, Lake Chembe and marsh). Seasons and dietary composition variably influenced the distribution, habitat selection and use by raptors. The three raptors devised a suit of behaviours to curtail challenges associated with seasonal food and water availability, and anthropogenic disturbances. There is a need to promote multi-stakeholder engagement and involvement in raptor conservation.     

Population trends and habitat use of Harlequin Ducks in Rhode Island

ABSTRACT.   To assess population trends of Harlequin Ducks ( Histrionicus histrionicus ) in Rhode Island (U.S.A.), we analyzed Christmas Bird Counts and other historical surveys and also conducted surveys during the winter of 2005–2006. We estimated sex and age ratios, evaluated the effects of tidal regime and time of day on survey precision, and quantified habitat use. The population in Rhode Island experienced logistic growth from 1976 to 2004, with approximately 150 birds now wintering at three primary sites in the state. We estimated that the current ratio of males to females in the region was 1.6:1 (62% males) and that 13% of males were first-winter birds. Most Harlequin Ducks were observed in rocky habitats within 50 m of the shore or offshore islands. We detected the greatest numbers of birds, with the least amount of variation, during morning surveys at low tide, suggesting that this may be the most appropriate time for population monitoring. Increases in the Rhode Island population and male-biased sex ratios may indicate a local population recovery resulting from a hunting ban initiated in 1990. Although most Harlequin Ducks in eastern North America winter in Maine, the population in Rhode Island represents one of the largest in the southern part of their range.     

Room to roam for African lions Panthera leo: a review of the key drivers of lion habitat use and implications for conservation

1. Globally, large terrestrial carnivores (Carnivora) have suffered precipitous declines in population and range. Today, they must persist in increasingly isolated natural habitat patches within a human-dominated matrix. Effective conservation aimed at supporting carnivores in such landscapes requires species-specific understanding of habitat requirements.
2. We present results from a review of the published literature to assess the current state of knowledge regarding habitat preferences of the African lion Panthera leo, with the aim of identifying common drivers of habitat use across contexts.
3. Using the Web of Science, we identified 154 usable articles and extracted information relating to study topic, location, habitats described, land-use type, and any documented habitat preferences.
4. Only 31 studies documented evidence of habitat use, and collectively, they suggested that preferences for specific habitat types were varied and context-specific. The importance of prey abundance and proximity to water was highlighted in multiple studies. Anthropogenic factors interfered with expected patterns of habitat use. There was evident bias in study locations: 83% of the habitat-use studies were based in only three countries, and 70% were focussed on protected or managed areas.
5. Our synthesis suggests that lions demonstrate behavioural plasticity in habitat use in response to anthropogenic pressures. To understand the limits of this plasticity and to manage Africa’s changing landscapes effectively for roaming lions, future research should be focussed on analysis of habitat use outside protected areas, taking into account gradients of distance to water, prey abundance, and anthropogenic risk.

     

The use of habitat mosaics by terrestrial vertebrate fauna: implications for conservation and management

Many species of vertebrates require multiple habitats to obtain different resources at different stages of their life-cycles. Use of habitat mosaics takes place on a variety of spatial and temporal scales, from a daily requirement for adjacent habitats to seasonal use of geographically separated environments. Mosaics of habitats are also required in some species to allow ontogenetic habitat shifts, while in others each sex may have specific requirements that are met by different habitats. The extent and nature of animal movements are key (but generally poorly known) factors affecting the vulnerability of species to landscape change. The requirement by many species for multiple habitats suggests that their conservation will be most effective in a mosaic environment and that protection of certain high profile habitats alone, such as rainforest, will be insufficient to achieve conservation goals. Management regimes that result in homogenization of habitats should be avoided. Priority should be given to research that identifies the extent to which species can locate habitat mosaics, at different spatial scales and arrangements, in modified environments.     

Individual feeding specialisation in shorebirds: population consequences and conservation implications

Individual feeding specialisation in shorebirds is reviewed, and the possilble mechanisms involved in such specialisations. Any specialisation can he seen as an individual strategy, and the optimum strategy for any given individual will be conditional upon its specific priorities and constraints. Some specialisations are related to social status and some to individual skills. Some are also probably frequency-dependent. However, most shorebird specialisations are constrained to a large extent by individual morphology, particularly bill morphology. For example, larger birds are able to handle larger prey, and birds with longer bills are able to feed on more deeply buried prey. Sex differences in bill length are uncommon in the Charardriidae, which are surface peckers, but are common in the Scolopacidae, which feed by probing in soft substrates. Sex differences in bill morphology are frequently associated with sex differences in feeding specialisation. There is evidence that different feeding specialisations are associated with different payoffs, in which case the probability of failing to reproduce or of dying will not be distributed equally throughout the population. I consider the population consequences of such feeding specialisations, particularly the different risks and benefits associated with different habitats or diets. I also consider the way in which individuals may differ in their response to habitat loss or change. I suggest that population models designed to predict the effect of habitat loss or change on shorebirds should have the ability to investigate the differential response of certain sections of the population, particularly different ages or sexes, that specialise in different diets or feeding methods.     

年龄、集群、生境及天气对鄱阳湖白鹤越冬期日间行为模式的影响

于2012年1—3月和2012年12—2013年3月,采用瞬时扫描法研究了鄱阳湖国家级自然保护区越冬白鹤(Grusleucogeranus)的昼间时间分配模式和日活动节律,分析了年龄、集群大小、生境类型和天气对白鹤越冬行为的影响。结果表明,白鹤越冬期的主要行为有觅食、警戒、理羽、游走、休息和争斗。其中,觅食是鄱阳湖越冬白鹤主要行为,占其昼间活动时间的82.94%;警戒占11.94%,理羽占3.52%,游走占1.88%,休息占0.15%,争斗占0.02%。白鹤在越冬期间的觅食、游走、休息和争斗行为存在明显的昼间节律性,其中游走、觅食和争斗行为在每天的上午和下午各存在1个高峰,休息行为在中午出现一个高峰;警戒和理羽行为则没有显著的昼间节律变化。年龄、集群大小、天气和生境对白鹤的越冬行为具有显著的影响:幼鹤取食的时间显著多于成鹤,而警戒时间则显著的小于成鹤;与家庭群中的个体相比,集体群中的个体取食和争斗时间显著增加,警戒时间显著减少;在天气晴朗时,白鹤的警戒时间显著大于阴天的警戒时间,取食时间则显著少于阴天时白鹤的取食时间;白鹤在大风天气显著增加理羽行为;在有雾的天气会显著增加取食时间,减少警戒时间。在草洲和浅水两种生境中,白鹤的游走和理羽行为存在显著差异,而觅食和警戒行为没有显著的差异,这可能源于草洲和浅水生境相互毗邻,并且具有相同程度的人为干扰。GLM分析结果表明,年龄和集群大小、年龄和生境、集群大小和天气、集群大小和生境、天气和生境对白鹤昼间时间分配模式的影响存在显著交互效应。     

Using presence‐only modelling to predict Asian elephant habitat use in a tropical forest landscape: implications for conservation

Aim Asian elephants, Elephas maximus, are threatened throughout their range by a combination of logging, large scale forest conversion and conflict with humans. We investigate which environmental factors, both biotic and abiotic, constrain the current distribution of elephants. A spatially explicit habitat model is constructed to find core areas for conservation and to assess current threats. Location Ulu Masen Ecosystem in the province of Nanggroe Aceh Darussalam on the island of Sumatra, Indonesia. Methods A stratified survey was conducted at 12 sites (300 transects) to establish the presence of elephants. Presence records formed the basis to model potential habitat use. Ecological niche factor analysis (ENFA) is used to describe their niche and to identify key factors shaping elephant distribution. An initial niche model was constructed to describe elephant niche structure, and a second model focused on identifying core areas only. To assess the threat of habitat encroachment, overlap between the elephants’ optimal niche and the occurrence of forest encroachment is computed. Results Elephants were recorded throughout the study area from sea level to 1600 m a.s.l. The results show that the elephant niche and consequently habitat use markedly deviates from the available environment. Elephant presence was positively related to forest cover and vegetation productivity, and elephants were largely confined to valleys. A spatially explicit model showed that elephants mainly utilize forest edges. Forest encroachment occurs throughout the elephants range and was found within 80% of the elephants’ ecological niche. Main conclusions In contrast to general opinion, elephant distribution proved to be weakly constrained by altitude, possibly because of movement routes running through mountainous areas. Elephants were often found to occupy habitat patches in and near human‐dominated areas. This pattern is believed to reflect the displacement of elephants from their former habitat.     

生境片断化对植物种群遗传结构的影响及植物遗传多样性保护

生境片断化是指大而连续的生境变成空间隔离的小种群的现象。生境片断化对植物种群遗传效应包括生境片断化过程中的取样效应及其后的小种群效应（遗传漂变、近交等）。理论研究表明,生境片断化后,植物种群的遗传变异程度将降低,而残留的小种群间的遗传分化程度将升高。然而对一些植物的研究表明,生境片断化对植物种群的遗传效应要受其他一些因素的影响,如世代长度、片断化时间、片断种群的大小、基因流的改变等。最后,针对生境     

Sex and age differences in habitat use by invasive cane toads (Rhinella marina) and a native anuran (Cyclorana australis) in the Australian wet–dry tropics

Although generalized habitat use may contribute to the success of invasive taxa, even species that are typically described as habitat generalists exhibit non‐random patterns of habitat use. We measured abiotic and biotic factors in 42 plots (each 100 × 10 m) along a 4.2‐km long unpaved road in tropical Australia, at a site that had been invaded by cane toads (Rhinella marina Bufonidae) seven years previously. We also counted anurans at night in each of these plots on 103 nights during the tropical wet season, over a five‐year period, beginning soon after the initial toad invasion. Spatial distributions differed significantly among adult male toads (n = 1047), adult female toads (n = 1222), juvenile toads (n = 342) and native frogs (Cyclorana australis Hylidae, n = 234). Adult male toads were closely associated with water bodies used as calling and/or spawning sites, whereas adult female toads and native frogs were most commonly encountered in drier forested areas on sloping ground. Juvenile toads used the margins of the floodplain more than conspecific adults did, but the floodplain itself was rarely used. Understanding which components of the habitat are most important to specific age and sex classes within a population, or how invasive species differ from native species in this respect, can clarify issues such as the spatial and temporal location of ecological impact by an invader, and the most effective places for control of the invader with minimal collateral effects on the native biota.     

Seasonal home range dynamics and sex differences in habitat use in a threatened,coastal marsh bird

A comprehensive understanding of spatiotemporal ecology is needed to develop conservation strategies for declining species. The king rail (Rallus elegans) is a secretive marsh bird whose range historically extended across the eastern United States. Inland migratory populations have been greatly reduced with most remaining populations inhabiting the coastal margins. Our objectives were to determine the migratory status of breeding king rails on the mid‐Atlantic coast and to characterize home range size, seasonal patterns of movement, and habitat use. Using radiotelemetry, we tracked individual king rails among seasons, and established that at least a segment of this breeding population is resident. Mean (±SE) home range size was 19.8 ± 5.0 ha (95% kernel density) or 2.5 ± 0.9 (50% kernel density). We detected seasonal variation and sex differences in home range size and habitat use. In the nonbreeding season, resident male home ranges coincided essentially with their breeding territories. Overwintering males were more likely than females to be found in natural emergent marsh with a greater area of open water. Females tended to have larger home ranges than males during the nonbreeding season. We report for the first time the use of wooded natural marsh by overwintering females. Brood‐rearing king rails led their young considerable distances away from their nests (average maximum distance: ~600 ± 200 m) and used both wooded natural and impounded marsh. King rails moved between natural marsh and managed impoundments during all life stages, but the proximity of these habitat types particularly benefitted brood‐rearing parents seeking foraging areas with shallower water in proximity to cover. Our results demonstrate the importance of interspersion of habitat types to support resident breeders. Summer draining of impounded wetlands that are seasonally flooded for wintering waterfowl allows regrowth of vegetation and provides additional habitat at a critical time for wading birds.     

Patterns of plant diversity in Africa south of the Sahara and their implications for conservation management

Plant species richness and range-size rarity in Africa south of the Sahara is concentrated in centres of plant diversity and endemism. Distribution patterns of plants mapped in the Distributiones Plantarum Africanum series and selected taxonomic monographs are analysed using the computer programme WORLDMAP. The plants are divided into four groups: herbaceous geophytes, mesophytic herbs, light-demanding shrubs and woody genera. Each group has peaks of species richness and range-size rarity at locations different to the other groups. Herbaceous geophytes and mesophytic herbs have their peaks of species richness and range-size rarity in the same location, the western Cape for geophytes and the Crystal Mountain for mesophytic herbs, whereas light-demanding shrubs and woody genera have peaks in different places. The results are discussed in relation to possible factors determining species richness and endemism and their likely conservation significance.     

Winter bird communities in the northern Negev: species dispersal patterns, habitat use and implications for habitat conservation

Bird habitat conservation may require different management strategies for different seasonal bird assemblages. We studied habitat use by winter birds in forest and scrubland habitat patches in the northern Negev, Israel. Our goal was to assess whether differences in responses to landscape and habitat structure between breeding and non-breeding seasons require changes in future conservation plans that have been suggested for the Negev breeding bird community. We evaluated habitat and area effects on bird abundance and distribution and tested whether species habitat use during winter involves niche shifts. Compared with breeding birds, a larger proportion of winter bird species occupied both scrubland and forest. As in summer, forest bird species responded to habitat structure, whereas scrubland species were associated with both habitat structure and area. Resident birds disperse into habitats in which they were not present during summer. Consequently, for several species, the correlation between bird densities and environmental factors showed a better fit at the landscape rather than at the habitat scale. In addition, rather than niche shift, birds actually extended their niche breadth. Nest site selection may constrain bird distribution into a realized niche, smaller than their fundamental niche. Despite the scale differences in habitat use, the similar species diversity patterns between seasons suggest that both winter and summer birds would benefit from conservation of scrub patches larger than 50 ha, and enrichment of foliage layers within the planted forests.     

Effects of habitat fragmentation on provisioning rates, diet and breeding success in two species of tit (great tit and blue tit)

The aim of this study was to examine the effects of forest fragmentation on the ability of parent birds to provide their young with an adequate food supply. To examine whether prey population densities of the great tit (Parus major L.) and the blue tit (P. caeruleus L.) vary between study areas in different forest size classes we compared provisioning rates and chick diet and related these parameters to breeding success. We filmed 217 nests over two breeding seasons and collected data on frass fall as a general estimate of caterpillar availability. Nests which were attended by none or one parent only during filming (n = 46) were excluded from the analyses. In both years and for both species feeding rates were highest in the smallest fragments and lowest in the large forest. There was also a suggestion that differences in feeding rates between areas vary between years. We found no consistent tendency for prey size to change with forest size, although both species brought slightly smaller prey items to the nest in the smallest forest fragments and feeding rates correlated negatively with prey size. Caterpillars were the main item fed to nestlings, in both species. We found no evidence to suggest that either frass fall or the proportion of caterpillars in the diet varied with forest size. There was also no correlation between mean frass fall and the total number of caterpillars brought to the nests, in either species. Breeding success, as measured by clutch size, brood size, fledging weight and fledging success, did not differ between the small fragments and the large forest, in either species. There was also no relationship between provisioning rate (as concerns volume of prey fed to nestlings and the quality of chick diet) and breeding success parameters. In conclusion, this study does not suggest suboptimal foraging or breeding conditions in small fragments compared to a nearby large forest, for either species. Received: 23 June 1997 / Accepted: 29 December 1997     

Distribution,movement, and microhabitat use of the introduced predatory snail Euglandina rosea in Hawaii: implications for management

The purposeful introduction of the land snail Euglandina rosea, which feeds exclusively on snails and slugs, has been implicated as a major factor in the decline of diverse Pacific island land snail faunas. We report on the distribution, movement patterns, and microhabitat preferences of E. rosea in a gulch in the Waianae Mountains, Oahu, Hawaii, because such data will help focus management actions at a local scale to protect native snail populations in areas where E. rosea is established. The Waianae Mountains harbor many endangered or threatened snails, most currently found in isolated habitat patches near the ridges. Conversely, most living individuals (28/29) and shells (46/56) of E. rosea were collected within the gulch, which supported higher densities of other native and non‐native snails, and was cooler and more moist than the ridges. Thirteen individuals of E. rosea were tracked (eight directly using a bobbin and thread method, and five indirectly by mark–recapture); most (10/13) moved on average <2.5 m per week (range 0.1–25.21 m), and all stayed within the gulch. Members of E. rosea preferred leaf litter over open, fern/shrub, or wood microhabitats. There were large differences in the population density of E. rosea over small spatial scales, indicating that there may be places where native snail populations could persist even in areas where populations of E. rosea are established. Identifying areas with differing population densities of E. rosea is critical for not only understanding why some native snail species may be more vulnerable to extinction, but also to locate areas where predation pressure is low and conservation efforts will be most likely to succeed.     

Optimal habitat conditions for the globally threatened Aquatic Warbler Acrocephalus paludicola in eastern Poland and their implications for fen management

To identify optimal habitat for the Aquatic Warbler Acrocephalus paludicola, a flagship species of fen mires, we related numbers of singing males to habitat variables in all core breeding sites in eastern Poland. The density of male Aquatic Warblers increased with increasing ground cover by water and mosses and litter layer height, and was highest where vegetation was 60–90 cm tall. Male densities also increased with the biomass of arthropods > 10 mm length, estimated by sweep netting, and with the abundance of spiders, estimated by pan trapping. We suggest that habitat management should take into account species‐specific morphological adaptations, nest safety and arthropod productivity. Prevention of vegetation succession is a conservation priority for open fen mires. However, modern management practices to achieve this, especially mowing using tracked vehicles, should be evaluated and optimized to ensure that such practices do not adversely affect the long‐term development of moss cover and litter structure.     

六盘山华北豹的栖息地利用及保护建议

大型食肉动物对维持生态系统的结构和功能具有重要作用, 但大部分大型食肉动物处在持续的种群数量和分布面积下降之中, 面临着急迫的研究与保护需求。华北豹(Panthera pardus japonensis)是我国特有的豹亚种, 也是部分区域森林生态系统中仅存的大型食肉动物, 面临着生境破碎化等威胁。本研究使用红外相机调查了宁夏六盘山国家级自然保护区华北豹的分布, 通过构建占域模型分析了华北豹的栖息地利用, 预测了华北豹的适宜栖息地, 并评估了其生境破碎化格局。研究发现, 华北豹在六盘山的平均占域率约为0.135。华北豹偏好植被发育成熟、地势崎岖、温度较低、远离农田和公路的栖息地, 对于农田边缘和居民点等人类活动区域未显示出显著回避。研究识别的六盘山华北豹适宜栖息地主要沿六盘山东西两侧山脉分布, 55%的适宜栖息地斑块位于六盘山国家级自然保护区内。栖息地斑块面积平均为16 km², 最大达214 km², 约77%的栖息地斑块面积在10 km²以下。研究表明六盘山国家级自然保护区有效地保护了华北豹现有的适宜栖息地, 但仍存在栖息地破碎化和人类活动干扰等关键限制因素。建议通过栖息地改造、人类活动管理等方式增强六盘山华北豹适宜栖息地斑块连通性; 并通过推动华北豹跨省保护工作等举措促进华北豹种群扩散恢复。