Projected large-scale range reductions of northern-boreal land bird species due to climate change

Climate change is projected to be particularly strong in the northern latitudes. Thus, boreal or arctic species are especially susceptible to the effects of climate warming. In this work we forecasted changes in the distributions of 27 northern land bird species in the 21st century, based on predicted rates of climate change. We used climate and bird atlas data of Finland and northern Norway from 1971-1990 to establish bioclimatic envelope models for each species. Next, these models were applied to two climate scenarios (A2 and B1) from the general circulation model HadCM3 to forecast potential future distributions of the study species over a larger area also covering parts of nearby Sweden and Russia. This area stretches through the boreal and continental arctic zone in northern Europe. In the A2 scenario the predicted global change in mean temperature is 3.8 °C by 2100 and in the B1 scenario 2.0 °C. Our results suggest that most of the northern land bird species will lose most of their climatic space by 2080 both in the more severe (A2, average predicted range decline: -83.6%) and in the less severe scenario (B1, average change: -73.6%). A large proportion (over two thirds) of the species considered here is thus susceptible to major range contractions in this geographical region. These climate change-induced threats are of importance because the Arctic Ocean represents a natural barrier for northward movement of species. To reduce the negative effects of climate change on the northern species, relatively large areas of continuous habitats in a connected reserve network should be preserved.     

Long-term population changes among breeding shorebirds in the Outer Hebrides, Scotland, in relation to introduced hedgehogs (Erinaceus europaeus)

In 1974, hedgehogs (Erinaceus europaeus) were introduced to the island of South Uist, which forms part of an area holding one of the largest concentrations of breeding shorebirds in Western Europe. By the 1990s these mammals had spread widely and become major predators of shorebird eggs. Breeding shorebirds were surveyed in 1983, when hedgehogs were confined to a small part of South Uist. They were surveyed again in 2000 by when hedgehogs had occupied all of the southern part (South Uist and Benbecula) of the 250 km² of lowland shorebird nesting habitat for at least 10 years but had not yet colonised large parts of North Uist and adjacent small islands. Between surveys the overall numbers of shorebirds in the hedgehog-free northern zone increased by 9% but in the southern zone, where hedgehogs were present, numbers decreased by 39%. Population changes differed among species, but for all species the population in the hedgehog-free northern zone outperformed that in the southern zone. The most marked differences occurred in northern lapwing (Vanellus vanellus) and common redshank (Tringa totanus), which both showed large declines in the southern zone and moderate to large increases in the northern zone. The north-south differences in population change could not be explained in terms of habitat change and were probably largely driven by hedgehog predation.     

Potential climate change effects on the distribution of agricultural grassland in England and Wales

Abstract. The spatial distribution of agricultural grassland in England and Wales has been assessed using a land evaluation model applied to information describing soils, climate and topography on a 5 × 5 km grid. The model calculates land suitability for grassland from assessments of trafficability/poaching risk and yield class. The spatial distribution of agricultural grassland was modelled for a 30 year climatic baseline (1941–1970) and for incremental changes in temperature and proportional changes in precipitation relative to that baseline.
Model estimates for the current distribution of grassland suitability agree well with observed data of actual grassland distribution. The best suited land occurs in south west England, Wales, the Welsh borders and Cheshire with fragmented areas of well suited land in north west England and on the Pens and Humberhead levels.
The climatic sensitivity analysis suggests that grassland production in England and Wales is resilient to small perturbations in mean temperature (up to +2°C) and precipitation (±10%). The effect of increasing temperature by 1°C is almost completely offset by precipitation increases of 10% resulting in little change to the distribution of grassland suitability. However, greater temperature changes (+ 4°C) have a major influence on the ability of land to support intensively managed grassland because of increased drought stress. Results indicate that a change in the climate comparable with current best estimates for the future would benefit grassland on good quality land at higher altitudes.     

Role of climatic niche models in focal-species-based conservation planning: Assessing potential effects of climate change on Northern Spotted Owl in the Pacific Northwest, USA

Although well-studied vertebrates such as the Northern Spotted Owl (NSO) are often used as focal species in regional conservation plans, range shifts associated with climate change may compromise this role. I used the Maxent (maximum entropy) method to develop NSO distribution models from data on NSO locations, forest age, and an ensemble of climate projections. NSO presence was positively associated with the proportion of old and mature forest at two spatial scales. Winter precipitation was the most important climate variable, consistent with previous studies suggesting negative effects on survival and recruitment. Model results suggest that initial niche expansion may be followed by a contraction as climate change intensifies, but this prediction is uncertain due to variability in predicted changes in precipitation between climate projections. Although new reserves created by the US Northwest Forest Plan prioritized areas with greater biological importance for the NSO than did pre-existing reserves, the latter areas, which lie predominantly at higher elevations, increase in importance under climate change. In contrast with previous analyses of the region’s localized old-forest-associated species, vegetation rather than climate dominated NSO distribution models. Rigorous assessment of the implications of climate change for focal species requires development of dynamic vegetation models that incorporate effects of competitor species and altered disturbance regimes. The results suggest that, lacking such data, models that combine climate data with current data on habitat factors such as vegetation can inform conservation planning by providing less-biased estimates of potential range shifts than do niche models based on climate variables alone.     

Salt exploitation and landscape structure in a breeding population of the threatened bluethroat (Luscinia svecica) in salt-pans in western France

The Guérande salt-pans represent the main French breeding area of bluethroat, a migrating passerine. Salt exploitation has created a geometrical artificial landscape in which we investigated factors influencing spatial distribution and breeding success of this species using a Geographical Information System. We compared data for four sites in these salt-pans, for three zones in the most densely populated site, and for 2500 m² grid cells defined for this same site. This study showed the influence of (1) the level of salt exploitation activity, (2) the density of bank intersections, (3) the extent of area covered by Suaeda vera bushes and (4) the structural heterogeneity. The continued management of these salt-pans enhanced bird breeding success. Thus, traditional salt exploitation contributes directly to the conservation of bluethroat, considered as an endangered species in Europe.     

Life-history and ecological correlates of population change in Dutch breeding birds

Predicting relative extinction risks of animals has become a major challenge in conservation biology. Identifying life-history and ecological traits related to the decline of species helps understand what causes population decreases and sets priorities for conservation action. Here, we use Dutch breeding bird data to correlate species characteristics with national population changes. We modelled population changes between 1990 and 2005 of all 170 breeding bird species using 25 life-history, ecological and behavioural traits as explanatory variables. We used multiple regression and multi-model inference to account for intercorrelated variables, to assess the relative importance of traits that best explain interspecific differences in population trend, and to identify the environmental changes most likely responsible. We found that more breeding birds have increased than decreased in number. The most parsimonious models suggest that ground-nesting and late arrival at the breeding grounds in migratory birds are most strongly correlated with decline. Increasing populations are mainly found among herbivores, sedentary and short-distance migrants, herb- and shrub-nesting birds and large species with a small European range. Declines in ground-nesting and late arriving migrant birds suggest that agricultural intensification, eutrophication and climate change are most likely responsible for changes in Dutch breeding bird diversity. We illustrate that management strategies should primarily focus on the traits and causes responsible for the population changes, in order to be effective and sustainable.     

Climate change and translocations: The potential to re-establish two regionally-extinct butterfly species in Britain

Climate change is causing many organisms to migrate to track climatically-suitable habitat. In many cases, this will happen naturally, but in others, human intervention may be necessary in the form of ‘assisted colonisation’. Species re-establishments in suitable parts of their historic ranges provide an opportunity to conserve some species and to test ideas about assisted colonisation. Here, bioclimatic models of the distributions of two extinct British butterflies, Aporia crataegi and Polyommatus semiargus, were used to investigate the potential for re-establishment in Britain. Generalised additive models and generalised linear models were created to describe the species’ European distributions for the period 1961–1990. All models projected the British climate during this period to be suitable for both species. Thirty-year climate projections for the periods 1991–2020 and 2021–2050, and for three climate change scenarios, were then put into the models to generate projections of climatic suitability throughout the 21st century. British climate was projected to remain highly suitable for A. crataegi, but to decline somewhat for P. semiargus. Southern and eastern Britain were found to be the areas most likely to support suitable climate. This difference between the species appeared to be due in part to decreasing summer rainfall in climate change projections, as this should only benefit A. crataegi. It is concluded that, with further study of habitat requirements, both species could be reintroduced to Britain as part of a long-term European conservation strategy.     

Spatiotemporal variation of breeding gull species in a boreal lake complex in Finland: Implications for conservation

Understanding spatial and temporal patterns of species is a prerequisite for successful species and habitat conservation. Spatial variation in breeding sites of four gull species was studied in southern Finland in an oligo-mesotrophic lake complex covering almost 50 km² of water areas and 290 km of shoreline in three census periods in 1986-2004. Two of the species have declined and are regarded as red-listed in Finland (black-headed gull ridibundus and lesser black-backed gull L. f. fuscus) and two have increased (common gull L. canus and herring gull L. argentatus) in numbers during the past decades. The numbers of breeding pairs and the percentage similarity in the spatial distribution of pairs of each species in grid squares were compared between different census periods at resolutions of 0.25, 1 and 4 km². The common gull showed very high percentage similarity between the different census periods and consequently low spatial turnover in nesting sites, whereas the red-listed species, particularly the black-headed gull, had much higher spatial turnover. The spatiotemporal dynamics of gull species should thus be taken into account in conservation planning. If site protection is based only on information of breeding gulls in one year, a large or even major proportion of the breeding red-listed gulls might be outside the protected areas after a few decades. Due to the large spatiotemporal variation of red-listed gulls, areas to be protected should cover a rather large proportion of a boreal lake, not only individual islets or islands.     

福建将石自然保护区鸟类物种相对多度模型的拟合研究

应用对数级数分布模型、对数正态分布模型、几何级数分布模型和分割线段模型对福建将石自然保护区鸟类物种相对多度分布格局对比研究结果表明 ,对数级数分布模型、对数正态分布模型能较好地描述将石自然保护区鸟类多样性 ,而几何级数分布模型和分割线段模型则不适于描述该自然保护区鸟类多样性 ;“多度 /频度”图解可较好地反映对数级数分布模型拟合效果 ,丘陵山地鸟类群落物种相对多度不遵从对数级数分布 ,各生境群落百分率相似性指数说明各生境群落百分率相似性较低。     

A nine-year study of successful breeding in a Bonelli’s eagle population in southeast Spain: a basis for conservation

We analyse the factors influencing breeding success in a healthy population of Bonelli’s eagle (Hieraaetus fasciatus) from south-east Spain, a raptor that has suffered a serious decline in Europe. Between 18 and 33 pairs were annually monitored during the period 1994-2002. Several factors that may affect four breeding parameters were studied, namely human presence, vegetation, relief, climatic factors, intra- and inter-specific relationships, diet, prey abundance, nest building, adult mortality and age of reproduction. A consistently high breeding success was registered during the study period (productivity=1.43, SD=0.11), which was probably the result of high adult survival, adequate prey availability and mild weather conditions. However, a certain vulnerability to the presence of golden eagles (Aquila chrysaetos) and to human disturbance was observed. One interesting result was the reduced survival of young chicks on north-facing cliffs owing to colder conditions, which may partially explain the decline of the Bonelli’s eagle populations along its European distribution limits. We discuss the role of this healthy subpopulation in an Iberian metapopulation context, and propose that the potential interference of golden eagles should be taken into account when designing management strategies for Bonelli’s eagles. Finally, we pinpoint some conservation priorities and the importance of reducing the main causes of adult mortality (i.e. shooting and electrocution) to assure successful reproduction and survival of this species.     

The level of threat to restricted-range bird species can be predicted from mapped data on land use and human population

A key element in the efficient allocation of scarce resources for conservation is the identification of areas of high biological value and high threat. Habitat loss and human population density have proved useful predictors of spatial variation in the current threat status of species albeit at coarse spatial resolution. We present a global analysis, intersecting Endemic Bird Areas (EBAs), to which restricted-range bird species are endemic, with fine-scale data of agricultural extent and human population density and test: (a) how well variation in land use mapped at 0.5° × 0.5° resolution predicts spatial variation in threat status of species and (b) how the predictive power compares with that of human population density mapped at the same resolution. Variation among EBAs in the proportion of restricted-range species that are threatened can be predicted by both the proportion of land used for agriculture and human population density. Agricultural land use was a better predictor of threat status than human population. Further, the average levels of threat attributable to agriculture were better predicted by land use than human population density, whereas threats due to causes other than agriculture were equally well predicted by land use and human population density. We fitted quantitative empirical models to describe these relationships. These results could be used, together with spatially explicit future scenarios of land use change, to project the geographical distribution and magnitude of future threats to birds at global and regional scales.     

Fire is a key element in the landscape-scale habitat requirements and global population status of a threatened bird: The Mallee Emu-wren (Stipiturus mallee)

The Mallee Emu-wren (Stipiturus mallee) is a threatened, narrow-range passerine endemic to south-eastern Australia. To inform future conservation measures for this poorly known species, we used ecological niche factor analysis, habitat suitability modelling and distance sampling to determine landscape-scale habitat requirements and estimate the population size. Using GIS software, we integrated digital layers of ecogeographic variables with; (1) presence-only observations to derive and validate a habitat suitability model using ecological niche factor analysis, and (2) distance sampling to determine population distribution and densities across vegetation types. We detected populations in only five of seven reserves which they had occupied in 2000. We estimate the global population size to be 16,821 individuals (range 8431-39, 104), 68% greater than the previously estimated 10,000 individuals, with a single large reserve containing the majority (∼92%) of the global population. The Mallee Emu-wren is a habitat specialist, primarily occurring in mallee-Triodia vegetation that has not been burnt for at least 15 years. The highest densities were in vegetation associations containing at least a 15% cover of Triodia, however, time since the habitat was last burnt was the overriding factor in determining densities. Large-scale wildfires are a pervasive threat to the global status of the Mallee Emu-wren, and the risk to remaining populations is exacerbated by the adverse impact of prolonged drought and the potential for altered fire regimes caused by global warming. Evaluation of the global population status, and the continued wildfire threat warranted recent reclassification of the Mallee Emu-wren from Vulnerable to Endangered according to IUCN Red List categories and criteria.     

Spatial patterns of microbial denitrification genes change in response to poultry litter placement and cover crop species in an agricultural soil

Subsurface-banding manure and winter cover cropping are farming techniques designed to reduce N loss. Little is known, however, about the effects of these management tools on denitrifying microbial communities and the greenhouse gases they produce. Abundances of bacterial (16S), fungal (ITS), and denitrification genes (nirK, nirS, nosZ-I, and nosZ-II) were measured in soil samples collected from a field experiment testing the combination of cereal rye and hairy vetch cover cropping with either surface-broadcasted or subsurface-banded poultry litter. The spatial distribution of genes was mapped to identify potential denitrifier hotspots. Spatial distribution maps showed increased 16S rRNA genes around the manure band, but no denitrifier hotspots. Soil depth and nitrate concentration were the strongest drivers of gene abundance, but bacterial gene abundance also differed by gene, soil characteristics, and management methods. Gene copy number of nirK was higher under cereal rye than hairy vetch and positively associated with soil moisture, while nirS gene copies did not differ between cover crop species. The nirS gene copies increased when manure was surface broadcasted compared to subsurface banded and was positively associated with pH. Soil moisture and pH were positively correlated to nosZ-II but not to nosZ-I gene copy numbers. We observed stronger correlations between nosZ-I and nirS, and nosZ-II and nirK gene copies compared to the reverse pairings. Agricultural management practices differentially affect spatial distributions of genes coding for denitrification enzymes, leading to changes in the composition of the denitrifying community.     

The rise and fall of bobcat populations in New Hampshire: Relevance of historical harvests to understanding current patterns of abundance and distribution

Harvest records reveal that populations of bobcats (Lynx rufus) in New Hampshire have undergone substantial changes during the past 200 years. In the 1800s, a nearly continuous bounty program resulted in annual harvests that averaged ∼30 bobcats. Harvests increased in 1915, and fluctuated from 100 to 400 bobcats during the 1920s through the 1950s. In 1959, harvests peaked at 421 and then rapidly declined. By 1970, payment was made on only 10 bobcats, and legal status was changed from nuisance animal to game species in 1973. In 1989, trapping and hunting seasons were closed and bobcats were designated a protected species. After 15 years of protection, populations of bobcats seem to be remaining at modest levels. To understand what factors may have contributed to the remarkable rise and fall of bobcat populations, we compared the temporal distribution of harvests to comments by early naturalists, legislation to control bobcat abundance, and historical changes in land use. We then used two approaches with a geographic information system to identify the environmental features that may affect present-day populations. The empirical approach relied on a comparison of landscape characteristics associated with recent (1990-2004) observations of bobcats to characteristics found at a comparable set of random locations. We also examined the characteristics of townships that yielded the majority of historical bobcat harvests (1931-1965) and developed a process-oriented model to rank present-day habitat suitability. The irruption of bobcat populations coincided with the availability of early-successional habitats as abandoned agricultural lands reverted to second-growth forests during the first half of the 20th century. Likewise, bobcat populations rapidly declined as these forests matured and no longer supported abundant prey, especially New England cottontails (Sylvilagus transitionalis). Our efforts to identify habitat features associated with present-day populations had mixed results. The empirically derived model correctly classified only 52% of recent bobcat locations, whereas the process-oriented model indicated that nearly 88% of recent bobcat observations were associated with sites that were ranked at high suitability. The results of this study demonstrate the utility of information on historical harvests when addressing questions on the status of contemporary wildlife populations.     

1961—2010年气候变化对西南冬小麦潜在和 雨养产量影响的模拟分析

利用农业气象试验站作物资料及土壤资料,评价 APSIM-Wheat 模型在西南地区的适应性,应用该模型分析该地区1961—2010年冬小麦潜在和雨养产量的时空变化特征,通过逐步回归分析揭示小麦生长季主要气象因子对潜在产量和雨养产量的影响及相对贡献率。研究结果表明： APSIM 模型对该区5个常用小麦品种的模拟效果较好,模拟与实测生育期的均方根误差(RMSE)在7.0 d 以内,地上部分生物量和产量模拟值与实测值的归一化均方根误差(NRMSE)均低于25%,模型在西南地区具有较好的适应性。1961—2010年研究区域36%的站点冬小麦生长季总辐射显著降低,其中北部、东南部和南部中区最显著;68%的站点生长季≥0℃有效积温显著增加,西部增温显著;30%的站点生长季平均气温日较差显著减小,南部中区最显著;全区生长季总降水大面积减少但不显著,减少区主要位于最南端和东南部。模拟的冬小麦潜在产量在65%的站点呈显著减产趋势,南部中区和北部变化最明显;雨养产量在25%的站点显著降低,北部地区较明显,全区减产趋势较弱。减产显著的站点中,生长季辐射降低、温度升高、气温日较差减小对潜在产量降低的贡献率分别为45%、36%和2%,对雨养产量降低的贡献率分别为36%、39%和－8%,而降水减少对雨养产量降低的贡献率为7%。西南冬小麦生长季辐射降低、温度升高及降水减少共同导致了冬小麦潜在和雨养产量的显著下降,而气温日较差的降低对冬小麦潜在和雨养产量的影响分别表现为负作用和正作用,整体上辐射和温度的影响程度最大。     

三峡库区生境质量的地形梯度效应及对土地利用变化的响应

三峡工程的建设给区域土地利用及生态环境带来巨大变化.在此背景下研究其土地利用和生境质量的时空变化规律,对推进库区国土空间开发保护与高质量发展转型具有重要意义.该研究以三峡库区湖北段为研究对象,根据三峡工程建设时间节点,选取多期土地利用数据,用InVEST模型评估生境质量的时空分异特征,采用分布指数、地形位指数、地理加权...     

Using traits of species to understand responses to land use change: Birds and livestock grazing in the Australian arid zone

The expansion of the artificial water-point network and livestock grazing in arid and semi-arid Australia has significantly increased access to water by water limited herbivores and thus has potential to seriously negatively affect the unique endemic flora and fauna. We examined the effects of the expansion of the water-point network on the arid and semi-arid zone bird community, using data from the Atlas of Australia bird surveys of 1977-1981 and 1996-2001. We examined whether traits of species could be used to uncover the critical ecological processes altered by this land use change. We detected large scale declines in individual species. Species reliant on water for nesting and feeding declined more than other groups in the presence of high water-point density, likely through direct effects of livestock degrading habitat of both natural and artificial water points. The arid zone has no natural hoofed animals and livestock have significant impacts. Species that forage and nest on the ground also showed large declines, likely because of trampling and removal of vegetation by livestock and potentially through the indirect effect of water limited predators, dingos and foxes, expanding their ranges in response to the expanding network of water points in the landscape. This result was also apparent at large spatial scales so that these local-scale responses to water points translate into continental-scale population declines. Using traits of species to understand declines of bird species helped us to uncover which critical changes associated with the expansion of the water-point network most affected the bird community and therefore which species are most at risk.     

Sources of resistance to Hessian fly (Diptera: Cecidomyiidae) in Syria identified among Aegilops species and synthetic derived bread wheat lines

The Hessian fly, Mayetiola destructor (Say), is a major pest of wheat in North Africa, southern Europe, North America, and northern Kazakhstan. It is believed this pest (like wheat) originated in West Asia. The Syrian Hessian fly biotype has been found to be the most virulent worldwide, and has been used at the International Center for Agricultural Research in the Dry Areas (ICARDA) for screening wheat and its wild relatives to identify new sources of resistance. The screening was conducted in an insect rearing room set at 20°C and 70% RH using a Hessian fly population collected from Lattakia region, Syria. The experimental design was a randomized complete block with four replications. ‘Nasma’ (bread wheat) and ‘Cando’ (durum wheat) were used as susceptible and resistant checks, respectively. A total of 623 lines/accessions of wheat and its wild relatives (Aegilops and Triticum) were evaluated. Twenty-nine Aegilops accessions and four synthetic derived bread wheat lines were found resistant. The presence of dead first instars confirmed the resistance reaction and also showed that antibiosis is the major mechanism of resistance in these materials. These sources of resistance are used in ICARDA’s wheat breeding programs for the development of Hessian fly-resistant germplasm/varieties.     

From genetic diversity and structure to conservation: Genetic signature of recent population declines in three mouse lemur species (Microcebus spp.)

The exceptional biodiversity of Madagascar is threatened by anthropogenic landscape changes that took place during the 2000 years of human colonization. This study focuses on the influence of geographic distance and forest fragmentation on genetic diversity and population differentiation of three rare, nocturnal, arboreal lemur species in northwestern Madagascar. Historic declines in population sizes as a consequence of forest fragmentation are quantified and dated. Eighteen sites were visited, and a total of 205 Microcebus ravelobensis, 45 M. bongolavensis and 78 M. danfossi were genotyped with eight microsatellite loci. Genetic differentiation among the sites, as measured by F_ST, ranged from 0.01 to 0.19. These values were significant in almost all cases and indicated genetic structure in the samples. Isolation-by-distance was detected in one species and a STRUCTURE analysis indicated that fragmentation further promoted genetic differentiation. Bayesian methods revealed that populations from all three species underwent a major demographic collapse of around two orders of magnitude. This decrease probably began after the arrival of humans, most likely within the last 500 years. This result suggests that anthropogenic changes may have been limited during the first 1500 years of human colonization in all three ranges. Two of the study species (M. danfossi, M. bongolavensis) lack effectively protected areas in their ranges. Consequently, quick conservation actions are now needed in order to secure the remaining genetic diversity of these species.