Survival of Svalbard pink-footed geese Anser brachyrhynchus in relation to winter climate, density and land-use

1. Global change may strongly affect population dynamics, but mechanisms remain elusive. Several Arctic goose species have increased considerably during the last decades. Climate, and land-use changes outside the breeding area have been invoked as causes but have not been tested. We analysed the relationships between conditions on wintering and migration staging areas, and survival in Svalbard pink-footed geese Anser brachyrhynchus. Using mark-recapture data from 14 winters (1989-2002) we estimated survival rates and tested for time trends, and effects of climate, goose density and land-use. 2. Resighting rates differed for males and females, were higher for birds recorded during the previous winter and changed smoothly over time. Survival rates did not differ between sexes, varied over time with a nonsignificant negative trend, and were higher for the first interval after marking (0.88-0.97) than afterwards (0.74-0.93). Average survival estimates were 0.967 (SE 0.026) for the first and 0.861 (SE 0.023) for all later survival intervals. 3. We combined 16 winter and spring climate covariates into two principal components axes. F1 was related to warm/wet winters and an early spring on the Norwegian staging areas and F2 to dry/cold winters. We expected that F1 would be positively related to survival and F2 negatively. F1 explained 23% of survival variation (F1,10=3.24; one-sided P=0.051) when alone in a model and 28% (F1,9=4.50; one-sided P=0.031) in a model that assumed a trend for survival. In contrast, neither F2 nor density, land-use, or scaring practices on important Norwegian spring staging areas had discernible effects on survival. 4. Climate change may thus affect goose population dynamics, with warmer winters and earlier springs enhancing survival and fecundity. A possible mechanism is increased food availability on Danish wintering and Norwegian staging areas. As geese are among the main herbivores in Arctic ecosystems, climate change, by increasing goose populations, may have important indirect effects on Arctic vegetation. Our study also highlights the importance of events outside the breeding area for the population dynamics of migrant species.     

Climate change,phenology, and habitat degradation: drivers of gosling body condition and juvenile survival in lesser snow geese

Nesting migratory geese are among the dominant herbivores in (sub) arctic environments, which have undergone unprecedented increases in temperatures and plant growing days over the last three decades. Within these regions, the Hudson Bay Lowlands are home to an overabundant breeding population of lesser snow geese that has dramatically damaged the ecosystem, with cascading effects at multiple trophic levels. In some areas the overabundance of geese has led to a drastic reduction in available forage. In addition, warming of this region has widened the gap between goose migration timing and plant green‐up, and this ‘mismatch’ between goose and plant phenologies could in turn affect gosling development. The dual effects of climate change and habitat quality on gosling body condition and juvenile survival are not known, but are critical for predicting population growth and related degradation of (sub) arctic ecosystems. To address these issues, we used information on female goslings marked and measured between 1978 and 2005 (4125 individuals). Goslings that developed within and near the traditional center of the breeding colony experienced the effects of long‐term habitat degradation: body condition and juvenile survival declined over time. In newly colonized areas, however, we observed the opposite pattern (increase in body condition and juvenile survival). In addition, warmer than average winters and summers resulted in lower gosling body condition and first‐year survival. Too few plant ‘growing days’ in the spring relative to hatch led to similar results. Our assessment indicates that geese are recovering from habitat degradation by moving to newly colonized locales. However, a warmer climate could negatively affect snow goose populations in the long‐run, but it will depend on which seasons warm the fastest. These antagonistic mechanisms will require further study to help predict snow goose population dynamics and manage the trophic cascade they induce.     

Phylogeographic population structure of great reed warblers: an analysis of mtDNA control region sequences

A portion of the mitochondrial control region (494 bp) was sequenced in 106 great reed warblers sampled in six breeding populations in Europe and one wintering population in Africa. In total, 33 different haplotypes were found. There was little evidence of divergence between populations in northern and western Europe whereas the sample from Greece differed significantly from the other European breeding populations. The lowest haplotypc diversity was found near the distribution range limit in Sweden and in The Netherlands suggesting recent effects of bottlenecks/founder events in these areas. A neighbour-joining analysis of the different haplotypes placed the haplotypes into two distinctive clades, A and B. The divergence of the two clades was on average 1.29%. Accounting for the within cladc variation suggested a divergence time between these lines approximately 70 000 years BP. The frequency of the two clades changed longitudinally across Europe with the A haplotypc in the west and the B haplotypc in the east. All birds from Kenya carried the B haplotypc suggesting an origin of these birds east of Latvia/Greece. The long-term female effective population size was estimated to be 20 000 individuals, which is approximately 2% of current population size.     

湖南通道侗族自治县传统聚落的空间构建

湘西传统聚落作为一种为数不多的、保存完好的聚落景观之一,其保护研究是我国文化生态及其生物多样性保护研究的重要组成部分。以怀化市侗族传统聚落为研究对象,从传统风水学理念与现代生态位出发,探索传统聚落空间格局的构建方法和驱动因素,以期为传统聚落合理的生态位扩充和空间结构演变提供理论依据。研究表明:湘西传统聚落形成了东、南、西、北四面山林围护、中间宽敞开阔的独立地理空间结构,构建了符合大众追求的"山-林-屋-水-林"的理想聚落空间模式,而且民居建筑大多都"坐西朝东,背风向阳,靠山面水而建"。这种聚落是在自然、经济和文化三大因素共同影响下构成的复合生态系统,有其独特的运行机制。在传统聚落空间系统不断发展的过程中,应遵从其演变发展的客观规律,根据不同传统聚落的生产力水平条件,合理推进经济社会空间结构的转型,并适度加以调控,以稳步实现传统聚落的空间演变和生态位扩充。     

Rapid recovery of Dutch gray seal colonies fueled by immigration

Gray seals were first observed breeding in the Dutch Wadden Sea in 1985, after centuries of absence. The breeding colony there is now the largest on the European continent. We describe the changes in gray seal numbers and their geographical expansion, and estimate how these processes were influenced by immigration from other colonies. Counts of hauled out animals were carried out between 1985 and 2013, monitoring three different periods of the seals' annual cycle. Using priors determined for the UK population, a Bayesian demographic model was fitted to pup numbers to estimate the population parameters driving the growth. This included immigration of subadults into the breeding population, which contributed to an average growth rate in the pup counts of 19%/yr, much higher than expected in a closed population. This immigration may account for approximately 35% of the total annual growth. In addition, at least 200 gray seals from the UK visit the area temporarily. Recovery of the population in the Netherlands occurred more than 50 yr after gray seals were protected in the UK. These time scales should be taken into account when studying long living marine mammals, e.g., in impact and conservation studies.     

Temporal and spatial distribution of malaria within an agricultural settlement of the Brazilian Amazon

Malaria has reemerged in tropical regions with rapid population growth and deforestation. The dynamics of malaria transmission in agricultural settlements of the Amazon have been poorly defined. We studied the spatial distribution of malaria incidence in Roraima, Brazil, using multi regression analysis on 12 parameters that described social, housing, and behavioral variables. Malaria cases were associated with the proximity of Anopheles darlingi breeding sites, the main vector in these areas. During the dry season, transmission was enhanced near a temporary river. Cases occurred throughout the year near fish‐farming dams. Epidemiological models derived from urban or riverine malaria are probably inadequate for describing disease transmission in agricultural settlements, where cases are clustered near breeding sites, while the majority of the population remains unaffected. Identification of these areas, associated with residual insecticide spraying or surveillance, may considerably decrease the costs of control efforts.     

Population genomic analysis uncovers African and European admixture in Drosophila melanogaster populations from the south‐eastern United States and Caribbean Islands

Drosophila melanogaster is postulated to have colonized North America in the past several 100 years in two waves. Flies from Europe colonized the east coast United States while flies from Africa inhabited the Caribbean, which if true, make the south‐east US and Caribbean Islands a secondary contact zone for African and European D. melanogaster. This scenario has been proposed based on phenotypes and limited genetic data. In our study, we have sequenced individual whole genomes of flies from populations in the south‐east US and Caribbean Islands and examined these populations in conjunction with population sequences from the west coast US, Africa, and Europe. We find that west coast US populations are closely related to the European population, likely reflecting a rapid westward expansion upon first settlements into North America. We also find genomic evidence of African and European admixture in south‐east US and Caribbean populations, with a clinal pattern of decreasing proportions of African ancestry with higher latitude. Our genomic analysis of D. melanogaster populations from the south‐east US and Caribbean Islands provides more evidence for the Caribbean Islands as the source of previously reported novel African alleles found in other east coast US populations. We also find the border between the south‐east US and the Caribbean island to be the admixture hot zone where distinctly African‐like Caribbean flies become genomically more similar to European‐like south‐east US flies. Our findings have important implications for previous studies examining the generation of east coast US clines via selection.     

Egg fertility among vasectomized and non‐vasectomized male resident Canada geese at the Wildlife Conservation Park/Bronx Zoo

In 1991, a vasectomy program was initiated at the Wildlife Conservation Park/Bronx Zoo to minimize the population growth of resident Canada geese (Branta canadensis). Sixty‐nine males were vasectomized over a 6‐year period. From 1994 to 1998, egg fertility was examined in females paired with vasectomized and non‐vasectomized geese. Of the 340 eggs laid by females paired with vasectomized males, 12% were fertile. In comparsion, of the 526 eggs laid by females paired with non‐vasectomized males, 90% were fertile. The vasectomy procedure was easier to perform on males captured during the breeding season than on those captured during molt owing to the enlarged size of the vas deferens. Where resident Canada goose populations are small and resources available, the implementation of a vasectomy program can be effective in reducing population growth. Zoo Biol 19:35–40, 2000. © 2000 Wiley‐Liss, Inc.     

ESR dosimetry study on population of settlements nearby Ust-Kamenogorsk city, Kazakhstan

The method of electron spin resonance (ESR) dosimetry has been applied to human tooth enamel, to obtain individual absorbed doses of residents of settlements in vicinity of Ust-Kamenogorsk city, Kazakhstan (located about 400 km to the east from the epicenter of explosion at the Semipalatinsk Nuclear Test Site, SNTS). This region developed as a major mining and metallurgical center during the Soviet period (uranium production). Most of the investigated settlements (Ust-Kamenogorsk city, Glubokoe, Tavriya, Gagarino) are located near the central axis of the radioactive fallout trace that originated from the surface nuclear test on 24 August 1956, while the Kokpekty settlement (located 400 km to the Southeast from SNTS) was chosen as a control because it was not subjected to any radioactive contamination. In total, 44 samples were measured. It was found that the excess doses obtained after subtraction of natural background radiation ranged up to about 114 mGy for residents of Ust-Kamenogorsk city, whose tooth enamel was formed before 1956. For residents of Gagarino, excess doses did not exceed 47 mGy for all ages. For residents of Tavriya, the maximum excess dose was 54 mGy, while for residents of Glubokoe it was about 58 mGy. For the population of the Shemonaikha settlements located at a distance of about 70 km from the central axis of the radioactive fallout trace, highest excess doses were 110 mGy. These high doses may be due to the influence of uranium enterprises located in that region, but probably not due to dental X-ray irradiation. For a final conclusion on the radiological situation in this region, the number of samples was too small and, therefore, more work is required to obtain representative results.     

A Perplexing Outbreak of Mice in Patagonia,Argentina

Early in spring, 1997, remarkably large numbers of mice appeared in the dense forests near the western end of Lago Nahuel Huapi, Argentina. Dead mice that washed up on nearby beaches at this time were fat, had full stomachs and were young or young-adults born unusually late in the preceding autumn and winter. These mice represented an aperiodic outbreak that extended over 300 km along the Andes. By analysis of trapped samples, the demographics of the two main species in this outbreak (Oligoryzomys longicaudatus and Abrothrix longipilis) were compared with demographics of the same species during the preceding 21 years. In spring of 1997, trap success for O. longicaudatus in areas of the outbreak was as high as 46%; for A. longipilis it was 22%. Neither males nor females of either species entered breeding condition in 1997 during the usual season of reproduction in spring, nor in the following summer, leading to the collapse of the populations. Numbers of Oligoryzomys decreased steadily to 15% in autumn and a normal 2% in the following spring, at which time reproduction resumed. The 1997 springtime populations in adjacent ecotone and steppe habitats to the east had not increased, contained no young individuals, and overwinter individuals reproduced normally. During the breeding season, O. longicaudatus in these populations increased more rapidly than did A. longipilis, and during the winter, they decreased faster. The unusual winter reproduction preceding the outbreak may have resulted from an increase in some deep-forest food source that in turn was responding to two successive, unusually warm winters. Predation played a negligible role in the population collapse. The mouse outbreak was not accompanied by an increase in human cases of hanta pulmonary syndrome, a disease for which O. longicaudatus is a reservoir.     

The dynamics of landscape change and snow geese in mid-continent North America

The Mid‐Continent Population of the lesser snow goose, which breeds in the eastern and central Canadian Arctic and sub‐Arctic, and winters in the southern United States and northern Mexico has increased 5–7% annually from the late 1960s to the mid‐1990s, largely because of increased survival in response to an agricultural food subsidy. The rise in numbers complements the increased use of nitrogen fertilizers and a corresponding rise in yields of rice, corn, and wheat along the flyways and on the wintering grounds. In sub‐Arctic migration areas and at Arctic breeding colonies, foraging by high numbers of birds has led to loss of coastal vegetation, adverse changes in soil properties and the establishment of an alternative stable state of exposed sediment, which can be detected with LANDSAT imagery. At a local scale, gosling growth, size and survival decreased in affected areas and other taxa have been adversely affected. The food subsidy on wintering and migration areas appears insufficient to meet reproductive demands as foraging in spring continues to occur on southern Hudson Bay staging and nesting areas. The recent introduction of liberal hunting regulations may reduce population size in the near term, but the revegetation of these coastal ecosystems will take decades to achieve. The present pattern of vegetation loss in these Arctic coastal systems is likely to continue in the forseeable future.     

Ka'apor ritual hunting

Several investigators cite population control, frequent settlement relocation, trekking, expansion of diet breadth, and food taboos as strategic responses to game depletion by indigenous populations living in interfluvial zones of lowland South America. The Ka'apor Indians of the interfluvial forest of northern Maranhão, Brazil, employ other means of optimizing hunting efficiency, partly based on ritual. Menstruating women, pubescent girls, and parents of newborns can consume meat only of the tortoise (Gochelone denticulata), the first prey species to be hunted out of an area. Tortoise capture requires, on average, one full day of hunting. This means that the full potential of hunting pressure does not materialize near the settlement. Meat productivity is unusually high even near old settlements. I argue that ritual tortoise hunting helps to regulate environmental utilization, to maintain a sustained yield of meat protein, and to expand the catchment area gradually.     

Predation of wood mice (Apodemus sylvaticus) on hibernating bats

Bat hibernacula with high numbers of bats can become high-risk areas, as they attract flying and non-flying predators. In order to protect hibernating bats effectively, more knowledge about mortality factors is needed. During the winters of 2003–2015, we found 214 dead bats in 12 hibernacula in The Netherlands province of Zuid-Holland. Most bat remains were found in December and January, with a second peak in April. Their remains showed a typical pattern of lesions consistent with those caused by predation by the wood mouse (Apodemus sylvaticus). Trail camera surveys showed that wood mice actively searched for bats. Predation pressure seemed to vary between winters, with a peak in the winters of 2004, 2011 and 2015. The annual mortality (relative to the maximum winter population size) caused by wood mouse predation varied between 0.1 and 8.8 %, with a maximum local effect of 83.6 %. The years with high wood mouse predation pressure were characterized by a long frost period and a low mast production of common oak in the preceding autumn. The size of a hibernaculum and the population density of its bats had an effect on predation-dependent mortality. The highest predation risk occurred near the entrance of bunkers. From these results we tentatively conclude that predation is not incidental and that wood mice actively search for and kill hibernating bats or scavenge for weakened individuals.     

Predator–vole interactions in northern Europe: the role of small mustelids revised

The cyclic population dynamics of vole and predator communities is a key phenomenon in northern ecosystems, and it appears to be influenced by climate change. Reports of collapsing rodent cycles have attributed the changes to warmer winters, which weaken the interaction between voles and their specialist subnivean predators. Using population data collected throughout Finland during 1986–2011, we analyse the spatio-temporal variation in the interactions between populations of voles and specialist, generalist and avian predators, and investigate by simulations the roles of the different predators in the vole cycle. We test the hypothesis that vole population cyclicity is dependent on predator–prey interactions during winter. Our results support the importance of the small mustelids for the vole cycle. However, weakening specialist predation during winters, or an increase in generalist predation, was not associated with the loss of cyclicity. Strengthening of delayed density dependence coincided with strengthening small mustelid influence on the summer population growth rates of voles. In conclusion, a strong impact of small mustelids during summers appears highly influential to vole population dynamics, and deteriorating winter conditions are not a viable explanation for collapsing small mammal population cycles.     

MATRIARCHAL POPULATION GENETIC STRUCTURE IN AN AVIAN SPECIES WITH FEMALE NATAL PHILOPATRY

We employ mitochondrial (mt) DNA markers to examine the matrilineal component of population genetic structure in the snow goose Chen caerulescens. From banding returns, it is known that females typically nest at their natal or prior nest site, whereas males pair with females on mixed wintering grounds and mediate considerable nuclear gene flow between geographically separate breeding colonies. Despite site philopatry documented for females, mtDNA markers show no clear distinctions between nesting populations across the species' range from Wrangel Island, USSR to Baffin Island in the eastern Canadian Arctic. Two major mtDNA clades (as well as rare haplotypes) are distributed widely and provide one of the few available examples of a phylogeographic pattern in which phylogenetic discontinuity in a gene tree exists without obvious geographic localization within a species' range. The major mtDNA clades may have differentiated in Pleistocene refugia, and colonized current nesting sites through recent range expansion via pulsed or continual low-level dispersal by females. The contrast between results of banding returns and mtDNA distributions in the snow goose raises general issues regarding population structure: direct contemporary observations on dispersal and gene flow can in some cases convey a misleading impression of phylogeographic population structure, because they fail to access the evolutionary component of population connectedness; conversely, geographic distributions of genetic markers can provide a misleading impression of contemporary dispersal and gene flow because they retain a record of evolutionary events and past demographic parameters that may differ from those of the present. An understanding of population structure requires integration of both evolutionary (genetic) and contemporary (direct observational) perspectives.     

Climate effects on population fluctuations of the white-throated dipper Cinclus cinclus

1. Climate change may have profound consequences for many organisms. We have studied fluctuations in a population of the white-throated dipper Cinclus cinclus during 31 years (1978-2008) in a river system in southern Norway in relation to both large-scale and local weather conditions occurring during the non-breeding season. 2. Multiple regression and partial least squares regression were used to model the growth rate of the population, accounting for population size in the previous year. 3. Population growth was influenced by North Atlantic Oscillation (NAO), mean winter temperature, precipitation and timing of ice formation on the main lake in the river system in autumn. These variables explained 84% of the variation in population growth over the 31-year study period. 4. Local winter conditions played a prominent role in explaining the population fluctuations, which is plausible because the dipper depends on open water for foraging. In the study area, winters can be harsh and rivers and lakes may freeze and severely affect the subsequent population size of the dipper in spring. 5. The breeding population of the dipper does not seem yet to have reached a level where all possible territories in the area have been occupied, even after mild winters, and the estimated carrying capacity is also decidedly lower (66 breeding pairs) than the number of available territories. If the trend of milder winters continues, the population might increase in the future. However, strong climate variation is expected to continue in the future, and hence periods of rapid growth of the dipper population will probably be followed by severe declines.     

Population changes of Greater horseshoe bats studied near Bristol over the past twenty-six years

Capture censuses of Greater horseshoe bats involving about 35 hibernacula were consistently carried out over twenty-six years in two separate areas. Hibernacula were visited three times per winter. A control area (reduced disturbance) was visited once annually. Censuses showed similar trends in all three areas, and counts of bats at a breeding site showed similar trends to those hibernacula, hut much greater stability. All numbers fell sharply to about 50%, of the original level between the winters or 1962/3 and 1966/7, then more-or-less stabilized until the mid 1970s; rose in the late 1970s and early 1980s, and finally declined precipitiously in all areas in 1986 to about 30% of the 1962/3 figure. Numbers of juveniles born annually showed no relationship to the numbers reaching hibernacula during the subsequent winter, but was negatively related to the mean birth time in July. The final forearm length of juveniles is negatively related to birth time. A population control mechanism based on birth timing and subsequent growth is postulated and supported by reproductive studies.     

Predation Danger Can Explain Changes in Timing of Migration: The Case of the Barnacle Goose

Understanding stopover decisions of long-distance migratory birds is crucial for conservation and management of these species along their migratory flyway. Recently, an increasing number of Barnacle geese breeding in the Russian Arctic have delayed their departure from their wintering site in the Netherlands by approximately one month and have reduced their staging duration at stopover sites in the Baltic accordingly. Consequently, this extended stay increases agricultural damage in the Netherlands. Using a dynamic state variable approach we explored three hypotheses about the underlying causes of these changes in migratory behavior, possibly related to changes in (i) onset of spring, (ii) potential intake rates and (iii) predation danger at wintering and stopover sites. Our simulations showed that the observed advance in onset of spring contradicts the observed delay of departure, whereas both increased predation danger and decreased intake rates in the Baltic can explain the delay. Decreased intake rates are expected as a result of increased competition for food in the growing Barnacle goose population. However, the effect of predation danger in the model was particularly strong, and we hypothesize that Barnacle geese avoid Baltic stopover sites as a response to the rapidly increasing number of avian predators in the area. Therefore, danger should be considered as an important factor influencing Barnacle goose migratory behavior, and receive more attention in empirical studies.     

Genetic analysis of the population structure of socially organized oystercatchers (Haematopus ostralegus) using microsatellites

On the island of Schiermonnikoog (The Netherlands), the breeding population of oystercatchers can be divided into two groups: 'residents' and 'leapfrogs', based on their distinct social characteristics and limited probabilities of status change between breeding seasons. In order to investigate whether this social organization has caused local genetic differentiation, leapfrogs and residents were compared at eight polymorphic microsatellite loci. No significant genetic subdivision between residents and leapfrogs was observed (theta = 0.0000; 95% confidence interval (CI), -0.0027-0.0033), indicating that the oystercatcher population on the island of Schiermonnikoog has to be considered as one panmictic unit. Investigation of three additional locations in the northern part of The Netherlands did not reveal significant genetic population subdivision either (theta = -0.0005; 95% CI, -0.0045-0.0037), despite the fact that adult osytercatchers show extreme fidelity to their breeding localities. These results indicate panmixis and considerable levels of gene flow within the northern part of The Netherlands. Thus, the results from genetical analyses do not seem to be in agreement with observational data on the dispersal behaviour of breeding individuals. It is argued that the lack of population structure, locally on Schiermonnikoog as well as across larger geographical distances, is to be attributed to high levels of gene flow through dispersal of juvenile birds.     

Localized impact of livestock settlements on vegetation patterns in fir forests of Kashmir Himalaya

Among the many global drivers of ecosystem degradation, the long-term impact of livestock settlements on vegetation patterns and composition, and is one of the greatest hurdles to successful forest ecosystem restoration. In order to identify the ecological implications of human land use changes on vegetation patterns and composition, the current study was conducted for the first time in Fir Forests of Kashmir Himalaya, to illustrate how vegetation responds to livestock settlements. We took samples from forest types both near and far from livestock settlements (ALS and NLS, respectively). To collect data on forest types, we employed a systematic random sampling strategy. After evaluation of the important value index (henceforth IVI) for each plant species along with anthropogenic data of forests, we analyzed data using ordination and cluster analysis techniques. On comparative analysis, the lesser values for diversity indices have been found for at the forest types near livestock settlement. It was discovered that 36% species were unique to away from livestock settlements forest type and 18% species in near to livestock settlements forest type, but that maximum 46% of species were common to all forest types studied. Species composition was unevenly distributed along with various anthropogenic factors, according to the canonical correspondence analysis. Forests near livestock settlements were also discovered to affect species abundance and diversity by promoting the growth of weedy species. The abundant growth of weedy flora such as Cirsium falconeri, Polygonum aviculare, and Urtica dioica around livestock settlement, results in alterations of plant community composition. The findings revealed that cut trees contributed 16% of reported density at ALS forest type and considerably higher values 35% at NLS forest type, respectively. Findings of the study could be used to develop effective livelihood options and management policies for long-term forest harvest impacts in the Himalayas, resulting in the sustainable use of local forest reserves.