鸟类栖息地片段化研究的现状

栖息地片段化的形成及其影响的研究是鸟类生态学的研究热点之一。对鸟类栖息地片段化的研究内容进行了分类,阐述了存在的问题,展望了今后鸟类栖息地片段化研究与问题。     

动物栖息地选择评估的常用统计方法

利用合适的统计学方法能够更准确地理解动物的栖息地选择。本文通过对2003~2012年期间,10个国际期刊所发表的177篇关于鸟类和兽类栖息地选择论文的30种统计学方法进行分析,简要概述了目前流行的栖息地选择统计学分析方法及特点,同时对同时期的中文文献也进行了简要分析。目前关于动物栖息地选择较为流行的分析方法主要有逻辑斯蒂回归、资源选择函数、成分分析、广义线性模型、多元方差分析、基于欧几里德距离的方法、广义线性混合模型、生态位因子分析、基于个体模型、典型相关分析、物种分布模型等。广义线性模型、逻辑斯蒂回归、多元方差分析和基于欧几里德距离这些方法可以很灵活地用来分析数据,但是缺乏一个有生态学意义的理论框架。资源选择函数和生态位因子分析各自为栖息地选择研究提供了一个统一的理论框架。基于个体的模型是一个自下而上的过程,很难在系统水平形成理论。232篇国内文章中使用较多的方法是主成分分析、Mann-Whitney U检验、t检验、卡方检验、判别分析、方差分析、Vanderloeg选择系数和Scavia选择指数、逻辑斯蒂回归、Kruskal-Wallis H检验和多元回归分析等。在实际研究中,应根据所要解决的研究问题,选择切实可行的分析方法。     

丹顶鹤春迁期觅食栖息地多尺度选择——以双台河口保护区为例

双台河口保护区是世界濒危鸟类丹顶鹤大陆种群西线群体不同生活史阶段的重要栖息地。2008-2010年3-4月,采用定点观察法、二维坐标法、方差分析、因子分析等方法对保护区内春迁期丹顶鹤觅食栖息地的多尺度选择进行了监测分析。研究结果表明：(1)春迁期,该保护区丹顶鹤觅食栖息地选择包括2个尺度3个选择,即大生境尺度内觅食生境类型选择和小生境尺度内觅食区选择、觅食微生境选择;(2)觅食生境类型偏好选择芦苇沼泽(90.00%),也偶选玉米地、泥滩、草甸等生境;(3)觅食区选择通过宏生境因子和干扰因子来判定,宏生境因子包括明水面、堤坝和火烧地,距离均在30m以内;干扰因子包括居民区和油田等强干扰因子和道路等弱干扰因子,均采取远离的方式进行回避,居民区保持在1km以上,油田保持在2km以上,道路保持在300-500m;(4)觅食微生境选择通过微生境因子来判定,包括植被高度、植被密度、植被直径等,选择盖度小(<5%)且植被高度小于喙长的区域觅食。     

汶川地震对四川龙溪—虹口和唐家河自然保护区大熊猫栖息地利用格局的影响

2008年的汶川地震发生在大熊猫集中分布的区域,对大熊猫的栖息地造成了严重破坏.利用龙溪—虹口和唐家河两个国家级自然保护区地震前(2003～ 2007)和地震后(2008～ 2010)共计7年的大熊猫监测数据,就汶川地震对大熊猫栖息地利用格局的影响进行了分析.研究结果表明:(1)地震前5年,大熊猫对栖息地的利用格局在年间没有显著变化;(2)地震后的2年间,大熊猫对栖息地的利用格局在年间没有显著变化;(3)地震前后连续7年调查的样线中,大熊猫对栖息地的利用格局在年间没有显著变化;(4)在龙溪一虹口保护区,大熊猫对样线的利用与滑坡体的面积没有显著关系,即大熊猫对栖息地的空间利用没有受到滑坡体面积大小的显著影响;(5)虽然从现有资料发现地震对大熊猫栖息地的利用格局没有显著的影响,但仍然需要在震后加强对大熊猫及其栖息地的保护.     

城市鸟类对斑块状园林栖息地的选择性

园林因在城市中呈斑块状分布而具有许多岛屿栖息地的特性,其内部结构和景观水平的结构同时也受到城市化的影响。对杭州市20个园林中鸟类物种的选择性分布进行了调查和分析,重点探讨了鸟类物种与园林面积、内部结构、微栖息地类型的分布、景观水平的结构、人为干扰等栖息地因素的关系。结果表明,杭州城市鸟类对园林栖息地具有较强的选择性,这不仅与园林的面积有关,还与园林的形状、植被盖度、微栖息地类型、连通性、隔离度、周围用地以及人为干扰等多种因素密切相关。园林栖息地间的异质性以及鸟类物种与栖息地结构的密切关系是园林鸟类选择性分布的主要原因。     

峨眉山灰胸薮鹛冬季栖息地特征

对于特有珍稀鸟类的保护而言,了解其对特定栖息地的要求至关重要。灰胸薮鹛(Liocichla omeiensis)是我国西南山地一种特有的画眉科(Timaliidae)珍稀鸟类。2010~2013年冬季,采用样线法和样方法,在四川峨眉山对灰胸薮鹛的冬季栖息地特征进行了调查。沿山间公路、山脊或林中小径布设观察样线。样线共计26条,总长70 km。观察发现,灰胸薮鹛主要在常绿阔叶林林缘地带活动,海拔范围约500~1 300 m。共设置47个利用样方和25个对照样方。χ²检验的结果表明,灰胸薮鹛主要选择阳坡。与对照样方的差异性检验显示,灰胸薮鹛喜好利用海拔较低、乔木数量较少、乔木胸径较小、乔木均高较低、乔木盖度较小、灌木盖度较大、竹子均高较高、竹子盖度较大、草本盖度较大、藤本植物较丰富、植被总盖度较大和距林缘距离较小的生境。逐步判别分析结果表明,灌木盖度、草本盖度、竹子盖度和距林缘距离是区分利用样方与对照样方的关键因子,判别准确率达87.5%。灰胸薮鹛对冬季栖息地的选择主要与食物和隐蔽条件有关。     

新疆北塔山雪豹对秋季栖息地的选择

2004年9~10月,对新疆北塔山地区雪豹(Unicaunica)栖息地选择进行了调查。在选定的15条样带上测定了59个利用样方及30个任意样方的6种生境特征(海拔、地形、植被类型、生境平坦度、放牧状况和坡向),其结果如下:Vanderploeg和Scavia选择指数表明:雪豹对海拔、地形、植被类型、生境平坦度和坡向存在选择性:(1)雪豹偏好利用海拔2000~2200m,而避开2600~3000m区域;(2)倾向于悬崖底部和山嵴,避开山坡和山谷;(3)偏好于灌丛,避开森林;(4)避开平坦的开阔地;(5)倾向于选择非放牧区域活动;(6)倾向于选择北坡,避开南坡。对生境特征的主成分分析显示:前3个主成分(海拔、地形和植被类型)的累积贡献率达到75·76%,可以反映雪豹的栖息地特征,同时表明:影响雪豹栖息地选择的主要因素依次为放牧状况、植被类型、地形和生境平坦度。     

四川宜宾地区云豹的潜在猎物资源与潜在栖息地景观格局研究

云豹Neofelis nebulosa是国家Ⅰ级重点保护野生动物,被世界自然保护联盟(IUCN)濒危物种红色名录列为易危(VU)等级,习性隐秘且树栖性强,我国对其野外生存状况鲜有研究。四川省宜宾市是云豹的历史分布区,自2007年发现云豹实体后再无记录报道。2018—2019年,采用样线法和红外相机陷阱法对宜宾市可能有云豹分布的3个县(长宁县、兴文县和珙县)进行了野外调查,结果显示:(1)未发现云豹的活动痕迹或实体;(2)共记录到云豹潜在猎物13种:哺乳动物7种、鸟类6种。(3)适宜云豹生存的阔叶林面积较小,仅有172.37 km~2,占研究区域总面积的16.77%;潜在适宜栖息地面积515.95 km~2,占50.21%,但潜在栖息地被道路切割严重,最大斑块面积为230.39 km~2,最小斑块面积为48.85 km~2。研究表明,云豹现有潜在栖息地破碎化严重,其偏好的阔叶林面积小、猎物资源匮乏,较难持续维持云豹种群的稳定发展。建议开展长期的红外相机监测工作;同时加强生境恢复和保护,以保护生物多样性和珍稀濒危物种种群。     

千岛湖陆桥岛屿鸟类集团对栖息地片段化的敏感性及其季节变化

为探究千岛湖陆桥岛屿不同鸟类集团对栖息地片段化敏感性的差异和季节变化,于2009年4月—2012年1月鸟类繁殖季(4、5、6月)和冬季(11、12、1月)对千岛湖41个陆桥岛屿鸟类集团进行了研究。结果表明,冬季杂食鸟对片段化敏感性高于食虫鸟,繁殖季时二者无显著差异,繁殖季和冬季时下层鸟对片段化敏感性均高于林冠鸟,冬季留鸟对片段化敏感性高于候鸟,繁殖季则无显著差异。杂食鸟和留鸟对片段化敏感性存在季节差异,而食虫鸟、林冠鸟、下层鸟和候鸟对片段化敏感性均无季节差异。不同鸟类集团对栖息地片段化敏感性的差异和季节变化规律,有助于人们在栖息地管理和保护区设计时采取更有针对性的鸟类保护措施。     

卫星跟踪技术在候鸟迁徙研究中的应用

自20世纪80年代末期应用基于Argos系统的卫星跟踪技术开展候鸟迁徙研究以来,鸟类学家取得了许多利用传统鸟类迁徙研究方法所无法取得的成果。但在中国,卫星跟踪技术在鸟类迁徙中的应用尚属空白。作者利用参与中国首次应用卫星跟踪技术跟踪候鸟迁徙研究之机,对该技术用于候鸟迁徙研究的技术平台、主要内容和未来研究进行了综述和展望。利用卫星跟踪技术开展的主要研究内容有:揭示迁徙路线和重要停歇地点;寻找新繁殖地和越冬地;利用卫星数据对栖息地及其利用进行评价;探讨鸟类的迁徙策略。期望该技术能够成为中国濒危鸟类保护的有效方法,并尽快得到应用。     

Roosting behavior of a Neotropical migrant songbird, the northern waterthrush Seiurus noveboracensis, during the non-breeding season

Several species of Nearctic-Neotropical migratory songbirds appear to form roosting aggregations while on their wintering grounds but little is understood about the ecology of this behavior. We studied roosting behavior and patterns of roost habitat selection in the northern waterthrush Seiurus noveboracensis , during three winter years (2002–2004) in Puerto Rico using radio telemetry. Overall, red mangrove was selected for roosting disproportionately to its availability. Regardless of diurnal habitat used, 87% (n=86) of northern waterthrush selected dense stands of coastal red mangrove for roost sites. Individuals traveled up to 2 km to access roost sites in this habitat on a daily basis. The majority (8 of 14) of individuals roosted alone, while others roosted in loose aggregations near communal roosts of gray kingbirds Tyrannus dominicensis . Patterns of roost site selection did not vary by sex. Individuals showing aggressive response to playback during the day, however, selected roost sites significantly closer to the coast. Several additional migratory and resident bird species also used red mangrove for night-time roosting habitat. Red mangrove may be a critical nocturnal roosting habitat for bird populations that live in proximity to coastal areas in the Neotropics. The benefits of nocturnal roosting behavior as well as why individuals appear to select red mangrove remain poorly understood.     

Habitat selection and population trends in terrestrial bird species of Robinson Crusoe Island: habitat generalists versus forest specialists

Habitat loss and degradation on oceanic islands are key processes leading to population decline of endemic birds and facilitating the establishment of invasive bird species. In this study, carried out in the Robinson Crusoe Island, we assessed density and habitat selection of terrestrial bird species, including juan fernandez firecrown and juan fernandez tit-tyrant, two endemics, as well as green-backed firecrown and austral thrush, which apparently originate from the mainland. Results show that perturbed habitats contained a low density of the endemic species whereas the mainland species were significantly more abundant in perturbed scrub habitats. Bird species show different habitat selection patterns, with endemics selecting for native forest and mainland species selecting for perturbed habitats, or using them at random. Bird species experienced temporal trends in their overall population sizes, with the endemic tit-tyrant suffering a significant decline in its population size of about 63% between 1994 and 2009. Only mainland species exhibited temporal changes in habitat use, significantly reducing their densities in the preferred scrub habitats, possibly as a response to decreased habitat quality. Thrushes apparently were able to compensate the population decrease in one non native habitat type by using native forests, a habitat giving them the opportunity of preying on nests of endemic species. We conclude that endemic bird species behave as specialists whereas the mainland species must be treated as invasive generalists on Robinson Crusoe Island.     

On humans and wildlife in Mediterranean islands

Aim To investigate the effects of human‐induced landscape changes in Mediterranean islands on the ecological and evolutionary responses of bird communities and populations. The combination of mass extinction of large mammals and massive deforestation by humans was hypothesized to produce new selection regimes to which organisms were likely to respond. Habitat selection and niche breadth have been investigated at the scale of species, and phenotypic variation at the scale of local populations. Location The study was carried out along habitat gradients and in habitat mosaics at different spatial scales on the island of Corsica and in areas of similar size and structure in continental France. Methods Two sets of gradients have been used for investigating habitat selection and niche breadth: gradients of altitude, and gradients of vegetation structure. Population studies focused on the blue tit, Cyanistes caeruleus. Large samples of breeding attempts by this species in 10 habitats provided detailed data on phenotypic variation of fitness‐related traits both on Corsica and on the mainland. Results The extent of niche space used by birds differed substantially depending on which habitat gradient was considered. Many species have been found to contract their habitat niche along the elevation gradient on Corsica compared with the mainland, whereas all species in the vegetation gradient broadened their niche on the island. Breeding patterns of the blue tit differed considerably depending on whether they settle in deciduous oaks (Quercus humilis) or in evergreen sclerophyllous oaks (Quercus ilex). Phenotypic variation of breeding traits was much higher on the island, where more populations were correctly timed for the best breeding period than on the mainland, a pattern that is likely to result from lower dispersal of organisms on the island. Main conclusions The differences in observed niche breadth between the two series of habitat gradients is explained both by the species‐specific ecology of the species and the human‐induced environmental history of Corsica. Large‐scale landscape changes provided new opportunities for island colonization by non‐forest species, which are isolated as small, ‘fugitive’ local populations. In both gradients, forest species that are typical components of the Corsican bird fauna definitely expanded their niche and occupied a wider range of habitats on Corsica than on the mainland. At the population scale, landscapes included habitat patches with contrasted selection regimes, which resulted in high phenotypic variation for many fitness‐related traits. Reduced dispersal of birds on the island resulted in a much higher degree of local differentiation on Corsica than on the mainland.     

Differentiation of Mating Vocalizations in Birds: Acoustic Features in Mainland and Island Populations and Evidence of Habitat-Dependent Selection on Songs

Local environments can act as selective agents on some characteristics of birds’ songs, whereas other song traits may not reflect local genetic adaptation. Geographic variation in songs of two Australian bird species (red‐capped robins Petroica goodenovii, western gerygones Gerygone fusca) was studied to examine one component of the ‘habitat‐dependent selection’ hypothesis. This hypothesis suggests that: (1) the detailed spectral characteristics of male songs are an evolved response to local habitat conditions affecting signal propagation and detection and (2) parallel evolution of other fitness traits sets up the potential for assortative mating by female choice. To examine the first part of the hypothesis, I made comparisons among widespread mainland populations and an island population using two levels of analysis: a typological analysis of song morphology (phonology: notes, syllables, syntax, temporal pattern, repertoires) and a spectral analysis of acoustic characteristics of songs (mean frequency, Wiener entropy, frequency modulation) using an automated procedure of feature extraction (Sound Analysis Pro). Spectral analysis was also used to extract values of the same acoustic features from the background sound environment of each recorded population. The typological analysis revealed no differences among mainland populations of either species, but large differences between mainland songs and those on the island. In contrast, the spectral analysis revealed acoustic divergence among populations, both mainland and island. For both species, Wiener entropy of songs correlated negatively with that of the ambient sound environment, consistent with predictions of the habitat‐dependent selection hypothesis of environmental selection on signal design.     

Predation risk and resource availability explain roost locations of Whimbrel Numenius phaeopus in a tropical mangrove delta

Roosts are important sites for shorebirds in non‐breeding areas at night and during high tides. How the spatial configuration of food and risk of predation and disturbance influence roost site use in tropical locations remains poorly known. We analysed the locations of nocturnal roosts of Whimbrel Numenius phaeopus in mangroves of Sanquianga National Park, Colombia, with respect to variation in spatial variables related to food resources and risk of predation and disturbance. We contrasted characteristics of all 13 known nocturnal roost locations with those of all other mangrove islands (n = 209) within the limits of the park. We estimated the distance from roosts and other mangrove islands to foraging sites, and sources of predators and human disturbance. Larger areas of feeding habitat surrounded nocturnal roosts than other mangrove islands, and the average distance to individual feeding patches was shorter. Roosts were also more isolated than other islands, but proximity to sources of human disturbance did not differ. We conclude that Whimbrel roost site use in Sanquianga was best explained by a combination of access to feeding territories and isolation from potential sources of mainland predators, but not by avoidance of human disturbance. Beyond identifying factors influencing roost site selection, the large aggregations of individuals in single locations may suggest that presence of conspecifics itself also plays a role in the formation of Whimbrel roosts. We highlight the interaction of food and risk landscapes with intraspecific attraction on the roost site selection by Whimbrels and the importance of mangroves as roosting sites in tropical regions.     

Flying over water: how “On bird species diversity” influenced aquatic ecology

Habitat complexity has long been known to influence animal community structure by increasing the number of available habitats. Fifty years have passed since MacArthur brothers published the seminal paper “On bird species diversity”, which revolutionized studies of habitat structure. This paper first evidenced and quantified the relationship between species diversity (birds) and habitat structural complexity (the number of stratified layers of landscape vegetation). In this article, we aim to pay homage to R. H. MacArthur’s contribution and to briefly analyze the citation history and influence of “On bird species diversity”, focusing primarily on aquatic studies. We searched for all papers that cited “On bird species diversity” on Thomson Reuters (ISI—Web of Knowledge) and analyzed them for temporal citation trends. In addition, considering only aquatic papers, we explored whether and how habitat complexity was measured, as well as the ecological organization level, attributes of organisms, taxonomic groups and study design (observational or experimental). “On bird species diversity” citations increased over time, but this paper was less cited by limnologists compared to terrestrial and marine scientists. The majority of investigations in aquatic ecosystems quantified habitat complexity, but few used mathematical modeling. The high number of citations, which continues to increase, shows the great influence of “On bird species diversity” on ecological studies and typifies it as a classic in the ecological literature. However, the low citation frequency found in papers devoted to freshwater ecosystems indicates that limnologists in general neglect this original contribution in studies of habitat complexity.     

Roost site selection by Little Owls Athene noctua in relation to environmental conditions and life‐history stages

Roost site selection is a state‐dependent process, affected by the individual's costs and benefits of roosting at a specific site in the available environment. Costs and benefits of different roost sites vary in relation to intrinsic factors and environmental conditions. Thus, the cost–benefit functions of roost sites are expected to differ between seasons and life‐history stages, resulting in adjustments in roost site selection. Studying roost site selection throughout the year therefore provides information about year‐round habitat requirements at different life‐history stages. However, little is known about the roosting behaviour of birds. Here, the roost site selection of Little Owls Athene noctua was studied by repeated daytime location of 24 adult and 75 juvenile radiotagged individuals from July to November. Little Owls preferred sheltered roost sites such as tree cavities with multiple entrances. They increasingly used sheltered sites from summer to winter and preferentially used sheltered roost sites with low ambient temperatures. Juveniles used significantly less sheltered sites during dispersal than before and afterwards, and used less sheltered sites than adults within their home‐range. The survival probability of birds roosting frequently at exposed sites was reduced. Roost site selection is probably driven by the two mechanisms of predator avoidance and thermoregulation, and the costs of natal dispersal may include increased predation threat and higher energy expenditure for thermoregulation. We suggest that adequate roost sites, such as multi‐entrance tree cavities, are an important habitat requirement for Little Owls and that habitat quality can be affected by manipulating their availability.     

Are Sage-Grouse Fine-Scale Specialists or Shrub-Steppe Generalists?

Sage-grouse (Centrocercus spp.) are influencing rapidly evolving land management policy in the western United States. Management objectives for fine-scale vegetation characteristics (e.g., grass height >18 cm) have been adopted by land management agencies based on resource selection or relationships with fitness proxies reported among numerous habitat studies. Some managers, however, have questioned the appropriateness of these objectives. Moreover, it remains untested whether habitat–fitness relationships documented at fine scales (i.e., among individual nests within a study area) also apply at scales of management units (e.g., pastures or grazing allotments), which are many orders of magnitude larger. We employed meta-analyses of studies published from 1991 to 2019 to help resolve the role of fine-scale vegetation structure in nest site selection and nest success across the geographic range of greater sage-grouse (C. urophasianus) and evaluate the validity of established habitat management objectives. Specifically, we incorporated effects of study design and functional responses to resource availability in meta-regression models linking vegetation structure to nest site selection, and used a novel meta-analytic approach to simultaneously model vegetation structure and its relationship to nest success. Our approach tested habitat relationships at a range-wide extent and a grain size closely matching scales at which agencies make management decisions. We found moderate, but context-dependent, effects of shrub characteristics and weak effects of herbaceous vegetation on nest site selection. None of the tested vegetation characteristics were related to variation in nest success, suggesting nesting habitat–fitness relationships have been inappropriately extrapolated in developing range-wide habitat management objectives. Our findings reveal surprising flexibility in habitat use for a species often depicted as having very particular fine-scale habitat requirements, and cast doubt on the practice of adopting precise management objectives for vegetation structure based on findings of individual small-scale field studies. © 2020 The Authors. The Journal of Wildlife Management published by Wiley Periodicals, Inc. on behalf of The Wildlife Society.     

Habitat selection and potential fitness consequences of two early‐successional species with differing life‐history strategies

Habitat selection and its relationship to fitness is a fundamental concept in ecology, but the mechanisms driving this connection are complex and difficult to detect. Despite the difficulties in understanding such intricate relationships, it is imperative that we study habitat selection and its relationship with fitness. We compared habitat selection of least terns (Sternula antillarum) and piping plovers (Charadrius melodus) on the Missouri River (2012–2014) to examine the consequences of those choices on nest and chick survival. We hypothesized that plovers and terns would select habitat that minimized the chance of flooding and predation of eggs, chicks, and adults, but that plovers would also select habitat that would provide foraging habitat for their chicks. We developed an integrated habitat selection model that assessed selection across multiple scales (sandbar and nest scales) and directly modeled the effect of selection on nest and chick survival. In general, the species selected habitat in keeping with our hypotheses, such that predation and flooding, in particular, may have been reduced. Sandbar selection had either a negative or no appreciable effect on nest survival for both species across years. Nest‐site selection in 2012 had a generally positive effect on nest survival and chick survival for both terns and plovers, and this trended toward a negative effect by 2014. This result suggested that early selection decisions appeared to be adaptive, but we speculate that relatively high site fidelity and habitat degradation led to reduced benefit over time. Our results highlight the complex nature of habitat selection and its relationship to fitness.