Are ricefields a good alternative to natural marshes for waterbird communities in the Camargue, southern France?

Rice cultivation has frequently been suggested to provide an important wetland habitat for waterbirds. However, in contrast to most other regions of the Mediterranean, the Camargue still has a substantial amount of surface area of natural marshes. Thus, we compared the abundance, species richness, and community composition of waterbirds in ricefields and natural marshes of the Camargue, during a one-year study. Based on surveys conducted at 4–7 day intervals in 1997–1998, our results suggest that natural marshes had substantially greater abundance of waterbirds, with ca. 99% of the individuals having been observed in natural marshes. Estimates of species richness and associated parameters further indicated that ricefields were clearly less rich than natural marshes. Although our results were rather striking for the Camargue, they may not be applicable to other regions because of the relatively high availability of natural marshes and differences in management of ricefields.     

广西沿海红树林区的水鸟

广西沿海地区位于一条重要的候鸟迁徙通道上，那里的红树林区给为数众多的水鸟提供了繁殖、越冬和迁徙中途歇息的场所。在红树林区记录到115种水鸟。这些鸟类中，102种是候鸟，包括13种夏候鸟、64种冬候鸟、25种旅鸟，因此红树林区水鸟类的多样性表现出明显的季节性。迁徙季节水鸟的种类和数量都最多，繁殖季节则最少。黑脸瑟鹭（Platalea minor)是世界上最濒危的鸟类之一，一个越冬种群在该地区红树林中被发现。     

New Anatidae population estimates for eastern China: Implications for current flyway estimates

Soundly-based conservation plans for Anatidae require abundance and distributional data to provide accurate estimation of population sizes and trends and to identify key sites for protection. Here, we report the first ever extensive surveys throughout eastern China’s wetlands for Anatidae, 80% of which occurred in the Yangtze floodplain. Population estimates for 24 species with sufficient data are provided, allowing assessment of the accuracy of current flyway population estimates; fourteen species are far less numerous than previously believed and three far more numerous. Further improvement of the population estimates for eastern China will need coordinated counts across the region requiring a large, skilled counter network.     

Preservation of wide-ranging top predators by site-protection: Black and red kites in Doñana National Park

We used data from a long-term study on two medium-sized generalist predators, the black kite (Milvus migrans) and the red kite (Milvus milvus), to illustrate the complexity of managing wide-ranging top predators by site-protection. The study was conducted between 1989 and 2000 in the Reserva Biológica de Doñana, located at the core of Doñana National Park. Both species occurred at high density and showed high productivity. Black kites were slightly increasing, and red kites showed a non-significant trend. The main cause of breeding failure was nest predation, mainly by mammalian predators, most likely Iberian lynx (Lynx pardinus) or common genet (Genetta genetta). The main cause of mortality was illegal poisoning, which sharply increased in the late 1990s. Nest-site selection models showed that: (1) black kites selected areas near the seasonal marshes, rich in their main prey species and (2) red kites selected areas rich in marshland and far from the park border, possibly in response to illegal poisoning episodes. Productivity was positively related to the availability of marshland and of open terrestrial habitats for black and red kites, respectively, and negatively related for both species to the density of black kites within 200 m of the nest. Our results showed that: (1) intraguild predation and competition among predators make outcomes of interspecific interactions extremely complex, leading to unpredictable side-effects of priority actions targeting one species at a time and (2) though the park was fenced and patrolled by wardens, the wide ranging behaviour of the two species made park borders permeable to negative human pressures, such as poisoning, leading to extreme edge effects and absence of a true, safe core of the park. Park management needs to be better integrated with its regional socio-economic and cultural context. Education programmes against illegal poisoning should be urgently promoted.     

The proportion of immature breeders as a reliable early warning signal of population decline: evidence from the Spanish imperial eagle in Doñana

Methods to evaluate population trends have recently received particular attention because of perceived declines in several species during the 20th century. We investigated whether age at first breeding could be used as an “early warning signal” to detect possible changes in population trends in long-lived species with deferred maturity using data from the Spanish imperial eagle (Aquila adalberti) population in Doñana National Park (Spain). This bird of prey is an endangered species that has suffered a rapid decline in this population during the last 10 years. As a result of our 27-year monitoring (1976-2002) study, we detected that an increase in immature breeding birds occurred before population decline became evident. The proportion of immature-plumaged breeders in the population was significantly higher during the period of decline than during the period of stability. In our case, more than 10% of immature breeders can be considered as an “early warning signal” that anticipates population decline. Owing to the ignorance of this warning signal, urgent actions for the recovery of this eagle population started 10 years later than necessary, and when population size had been reduced.     

The loss of coastal grazing marshes in south and east England,with special reference to east Essex,England

Freshwater, coastal grazing marshes provide an attractive habitat for breeding and wintering birds. In recent years, such areas have frequently been subjected to drainage improvements and conversion to arable.In east Essex, a land-use study of 16 000 ha of the coastal zone between Clacton-on-Sea in the north to Burnham-on-Crouch in the south showed that between 1938 and 1981, the area of coastal grassland decreased from 11749 ha to 2083 ha—a reduction of 9666 ha (82%). Most of this loss (92%) has occurred as a result of conversion to arable.The rates of conversion to arable were particularly high between 1938 and 1947 due to wartime increases in agricultural production and from 1970–1981, coinciding with Britain's entry into the European Community and favourable cereal prices under the Common Agricultural Policy.The rate of loss of east Essex coastal grazing marsh is compared with that for three other areas: Romney Marshes, Kent; North Kent Marshes; and the Broadland Marshes of Norfolk and Suffolk.     

Numbers of wintering waterbirds in Great Britain, 1994/1995-1998/1999: I. Wildfowl and selected waterbirds

Estimates of the number of waterbirds (principally wildfowl) wintering in Great Britain are presented, based on data from the period 1994/1995-1998/1999. These update the previous estimates for 1987/1988-1991/1992. National estimates are used to derive 1% thresholds for waterbird species which in turn form the basis for the identification of nationally important wetland sites for subsequent conservation and protection. Estimates are also used to assess changes in numbers of those species for which monitoring data are insufficient to calculate annual indices of population change. Data for calculating the estimates come from a variety of sources including the Wetland Bird Survey (WeBS, a long-term scheme which counts waterbirds by day at wetlands), goose roost censuses, site-based surveys and published reviews. Generation of the estimates is made difficult by a number of methodological and data quality issues. To account for some of the methodological problems affecting WeBS data, new methods for generating estimates have been used which account for birds missed during the counts in a more comprehensive manner. These result in large increases in the estimated numbers for many of the relevant species, although most are still considered to be underestimates. To assess the biological change in numbers since the last assessment, estimates generated from the same methods used previously are also presented. These indicate that while the majority of species have experienced increases in numbers since the late 1980s there have been some notable declines. There is however scope for improving the accuracy of estimates derived from extensive, volunteer-based monitoring schemes such as WeBS.     

Monitoring brown frogs Rana arvalis and Rana temporaria in 120 south Swedish ponds 1989-2005. Mixed trends in different habitats

The two brown frogs Rana arvalis and Rana temporaria were monitored at 57 localities (that contained a total of 120 ponds) for up to 17 years each during the years 1989-2005. The analysis summarized below only accounts for trends within sites actually usable for frogs during the analysis period, large scale habitat losses are thus not accounted for. R. arvalis populations tended to increase over the study period. R. temporaria populations displayed no significant change. However, both species displayed significant fluctuations from year to year. These were not correlated between the two species. Localities with permanent ponds tended to display more positive population trends than localities with temporary ponds and ponds in pastures tended to display more positive trends than those in forests. For ponds in cropped fields, where only R. temporaria were found, the trend were also generally negative. Thus, long-term trends suggest that neither species is in decline. Nevertheless, the population trends observed in more exploited habitats are less positive than those in relatively unexploited habitats. We conclude frog populations in agricultural habitats should be more carefully studied to identify the factors behind the decline. The negative trend in temporary ponds are cause for a closer analysis of the effects of weather factors on frog population dynamics.     

Long-term population declines in Afro-Palearctic migrant birds

We present the first continent-wide analysis of the population trends of European breeding birds to show that populations of Afro-Palearctic migrant birds have shown a pattern of sustained, often severe, decline. The mean trend of inter-continental migrants was significantly negative between 1970 and 1990 and non-significantly so between 1990 and 2000. Mean population trends were positively correlated between periods, suggesting little change in the trajectory of most migrant species’ populations over this 30-year period. In both periods, trends of inter-continental migrants were significantly more negative than those of short-distance migrants or residents. This negative trend appeared to be largely, although not entirely, due to declines in species wintering in dry, open habitats in Africa. Analyses of trends of 30 closely related pairs of species, one a long-distance migrant and the other not, indicated significantly more negative trends in the former, irrespective of breeding habitat. Conservation action to address these declines is required under the Convention on Migratory Species and the Pan-European Biological and Landscape Diversity Strategy, to which most European countries are signatories and which aim, respectively, to conserve migratory species and to halt the loss of biodiversity by 2010. Our results indicate that more conservation action may be required outside Europe to achieve these targets. Further research is needed to assess whether the declines are caused by factors operating on the birds’ wintering grounds, breeding grounds or on migration routes, and to identify ways to reverse them.     

Modelling the effect of El Niño on the persistence of small populations: The Galápagos penguin as a case study

Small populations are vulnerable to long-term declines, even where short-term censuses indicate increasing trends in numbers. Census data for the Galápagos penguin (Spheniscus mendiculus) collected between 1970 and 2004 provide evidence that despite year-to-year population increases detected in most of the annual censuses, the strong El Niño events of 1982-83 and 1997-98 were followed by population declines of more than 60% from which the species has yet to recover. Such large declines raise concerns about the future viability of the species because the frequency and severity of El Niño events are predicted to increase. We used the simulation software VORTEX to evaluate the potential effects of El Niño on the risk of extinction of the Galápagos penguin population and its four constituent subpopulations. Weak and strong El Niño events were treated as catastrophes, with varying frequencies, which simulated past, current and future effects on the penguin population. The “Current El Niño” scenario, based on the frequency of El Niño events recorded in the Galápagos between 1965 and 2004, indicated an approximately 30% probability of extinction within the next 100 years for the penguin population. More ominously, the species may be at a greater risk if the frequency of strong El Niño episodes increases only marginally. A probability of extinction greater than 80% was predicted when the current frequency (5%) of strong El Niño events was doubled (to 10%). The probabilities of extinctions were higher for each subpopulation treated individually, ranging from 34% for Isabela and Fernandina, 64% for Bartolomé-Santiago to 78% for the smallest subpopulation on Floreana. Sensitivity analyses identified survival of penguins during El Niño events and sex ratio as influential parameters. The estimates of extinction risk may be conservative as other threats associated with increased human activities on the islands may further compromise species persistence.     

Impact of human dwellings on the distribution of the exotic Argentine ant: a case study in the Doñana National Park, Spain

The invasive Argentine ant Linepithema humile was found in close perimeters to inhabited houses situated in various habitat types in Doñana National Park (Southern Spain). We suggest that the Argentine ant is found in these sites largely due to passive importation by man, but from there may have the potential to spread into surrounding favourable natural habitats. Ant species richness and diversity around houses was similar to that in natural habitats, except in the cases where the Argentine ant dominated, where a considerable lower ant species diversity and richness was observed. The species composition of ants in the immediate vicinity of houses was very different from that of the surrounding natural habitats, although the species composition between houses was very similar, regardless of the type of surrounding natural habitat. Ant species around houses were typically generalists, opportunists or open habitat specialists. Many of these species are considered dominant in that they are characterised by having large nests, aggressive behaviour and mass recruitment in response to attack. However, these species are displaced by the Argentine ant when introduced. Not all ant species show the same responses to invasions by the Argentine ant, and some species, such as Cardiocondyla batesii, Oxyopomyrmex saulcyi or Cataglyphis floricola, may be able to persist for a period following an invasion of the Argentine ant. These species are characterised by small nests and submissive behaviour, and may survive by avoiding conflict with the invasive species.     

Population trends of birds across the iron curtain: Brain matters

One approach to assess human impact on species’ population dynamics is to correlate ecological traits of species with their long-term population trends. Yet, few studies investigated population trends in multiple regions that differ in human impact to reveal which traits explain population trends over larger geographic areas and which only regionally. We examined the relationship between various species traits and long-term population trends of 57 common passerine bird species from 1991 to 2007 in three adjacent regions in central Europe that experienced differences in socioeconomic history: North-Western Germany, Eastern Germany and the Czech Republic. We tested effects of habitat, dietary and climatic niche, migratory strategy and cognitive ability, measured as relative brain size. We predicted that traits reflecting socioeconomic and land-use change had stronger effects in former communist countries than in North-Western Germany due to marked changes in these countries after 1990. We found that climatic niche and migratory strategy affected bird abundances similarly in all regions suggesting their influence is invariant across central Europe. In contrast, brain size showed regionally varying effects. The effects were negligible in North-Western Germany, slightly positive in Eastern Germany and strongly positive in the Czech Republic. Increases of species with large brains suggest that species with good cognitive abilities might have been better able to adapt to rapid socioeconomic change and make use of novel opportunities after the end of communism. Regional differences in population trends among species thus appear to be driven by an interaction between cognitive abilities and socioeconomic change.     

Traditional salt-pans hold major concentrations of overwintering shorebirds in Southeast Asia

Shorebirds are declining worldwide due to loss and degradation of critical breeding and wintering habitats. Some human-modified habitats, particularly salt-pans which are used by shorebirds in many regions of the world, may help substitute for natural habitats lost for a wide range of species during migration. We studied the influence of landscape characteristics on species richness, abundance, and diversity of shorebirds at 20 sites covering most of the Inner Gulf of Thailand, a landscape with a long history of salt farming. Sites with salt-pans present held significantly higher species richness, abundance and diversity of shorebirds. Areas with larger proportions given over to aquaculture tended to have lower species richness, abundance and diversity. Generalized additive models indicated that landscapes with a larger proportion of tidal flats in conjunction with salt-pans were the best predictors of sites with higher species richness, abundance and diversity. Landscape configurations with higher richness, abundance and diversity of shorebirds also tended to be less fragmented and contained slightly larger patches. Shorebirds appeared to use ponds with exposed mud in salt-pans as both roosting sites and supplementary feeding grounds during high tide. Traditional salt-pans therefore proved to contribute significantly to maintenance of overwintering shorebird populations in this landscape and should be investigated elsewhere in Asian coastal zones. Collaboration between researchers, salt farmers and planning authorities as to how best to maintain salt-pans as potential shorebird roost sites such as in the Inner Gulf of Thailand is urgently needed in order to maintain habitat for shorebird populations in critical wintering and staging areas of this flyway.     

Natural versus artificial- wetlands and their waterbirds in Sri Lanka

As natural wetlands have disappeared around the world, artificial wetlands have increased. We found interesting differences in waterbird communities of two natural (Bundala Ramsar site) and seven artificial wetlands (irrigation tanks, salt ponds, rice paddies) in south-east Sri Lanka. Eight species exclusively used natural and one species artificial wetlands. Migratory species (shorebirds 64%, terns 47%) dominated species’ richness of natural lagoons, with densities of shorebirds 3-6 times greater than on artificial wetlands. Contrastingly, resident species (dabbling ducks, gallinules) contributed most to the diversity (59%) and density of waterbirds on artificial irrigation tanks. Cattle egrets dominated waterbird density (>70%) of rice paddies. Waterbird communities reflected physical and chemical character of wetlands: natural wetlands were shallow (<2 m) and saline (EC > 1000 msm⁻¹) compared to deep (>2 m) and freshwater (EC < 110 msm⁻¹) artificial wetlands. Artificial inputs of water drained into the natural Embilikala lagoon changing its physico-chemical profile and disrupting the natural seasonal drying. Consequently its waterbird community was similar to artificial irrigation tanks, with shorebird species particularly impacted: densities half that of the other natural lagoon. Artificial salt ponds had similar physico-chemical properties to the natural Bundala lagoon and a similar waterbird community. Even though artificial wetlands supported waterbirds, they were not adequate replacements for loss of natural wetlands, favouring some species. Imposed hydrological stability degraded habitat quality for migratory shorebirds on one of our Ramsar site lagoons.     

A framework for monitoring the status of populations: An example from wader populations in the East Asian-Australasian flyway

The loss of biodiversity is an ongoing problem and it is essential that a framework is established for revealing the status, identifying threats and monitoring future changes of populations. This study focuses on wader populations in the East Asian-Australasian flyway, and aims to develop a three-step framework for monitoring the status of populations. First, population changes of waders are quantified by estimating population indices from nationwide survey data in Japan between 1975 and 2008. Second, species characteristics shared by declining waders are identified using a phylogenetic comparative method. Finally, based on the revealed characteristics of declining species, composite indices are created for monitoring changes in wader communities in the East Asian-Australasian flyway. The estimated population indices revealed that 12 species out of 41, and 16 out of 42 have declined significantly during spring and autumn migration, respectively, in at least one of the past 10, 20 or 30 year-periods. Phylogenetic comparative analysis revealed that both the use of rice fields and dependence on the Yellow Sea negatively affected the population trends of waders. These results are consistent with the hypothesized negative impact of agricultural intensification caused by land consolidation in Japanese rice fields, and habitat loss and/or degradation in the Yellow Sea caused by the rapid growth of populations and economies in China and South Korea. The framework developed in this study can be applied to a wide range of species, and should play an important role in monitoring population trends and identifying threats to those species in future.     

Challenging conservation of migratory species: Sahelian rainfalls drive first-year survival of the vulnerable Lesser Kestrel Falco naumanni

In the context of attested global changes, accurate estimation of whether climatic fluctuations impact on population demographic parameters is needed for adequate management, especially for migratory species. We present a capture-recapture analysis linking survival rates of the vulnerable Lesser Kestrel (Falco naumanni) to annual rainfalls in the Sahel region, considered as a proxy of climatic conditions on wintering grounds. Recapture data were obtained from field observations of individuals ringed and sexed as juveniles over a 14-year monitoring period (1994-2007). We addressed a common but problematic situation in birds where: (i) sex is known with certainty for first-summer or older birds but only suspected for juveniles, and (ii) a large proportion of individuals never return to the study population (e.g. transient behavior). Transient behavior and unknown sexes were explicitly integrated considering a two age class in a multistate capture-recapture model. Survival was time-varying for juveniles (geometric mean: 0.499 ± 0.021) but constant - and higher - for adults (0.718 ± 0.013). Yearling survival probabilities were strongly correlated with rainfalls in the Sahel, suggesting a high dependence of juvenile upon the wintering conditions. While taking sex uncertainty into account, we detected no sex-dependence in survival. Incorporating the sensitivity of survival of wintering migratory birds to climatic variables such as precipitations in arid Sahelian ecosystem may allow to model conservation scenarios with a greater realism. Finally, we encourage the development of international management strategies for migratory species on wintering areas in addition to the existing conservation actions on summering Mediterranean grounds.     

Behavioural response of a trophic specialist, the Iberian lynx, to supplementary food: Patterns of food use and implications for conservation

Prey scarcity compromises population survival, especially for specialist predators. Supplementary feeding is a management tool that can be applied to reverse the decline of food-limited populations. We analyse how a population of Iberian lynx, a threatened food specialist, initially reacted to, and subsequently used, supplementary food. Twenty-seven feeding stations (FS) with domestic rabbits were placed in the Doñana Biological Reserve, SW Spain, between 2002 and 2005. We recorded lynx tracks inside and around stations to analyse spatio-temporal patterns of use, as well as the performance of several station designs. Iberian lynx used 62% of the FS installed, and consumed most of the supplied food. All station designs were used and food provision apparently covered the energetic needs of the lynx inhabiting the reserve. There was spatial aggregation in the use of the FS. Fourteen weeks were needed on average for lynx to become familiar with feeding stations and making a regular use of the supplementary food. Seasonal variations in consumption frequency appeared to be modulated by fluctuations of wild rabbit numbers throughout its annual cycle as well as by variation in energy demand of breeding females. The Iberian lynx responded positively to our supplementary feeding programme. We show that this technique allows the persistence of lynx populations during long periods in areas where wild rabbits are extremely scarce. Supplementary food may be used to sustain lynx whenever rabbit populations need recovery, as well as in the context of lynx restocking or reintroduction programmes.     

Effects of human activities on migratory waterbirds at Lashihai Lake, China

Surveys on migratory waterbirds and their habitats at Lashihai Lake, China, were conducted from October 1999 to April 2000. Five fixed points, representing different degrees of habitat disturbance and quality, were selected around the lake. We used counts (n=30) to compare diversity and abundance of waterbirds at each point and evaluate the effects of habitat disturbance. The distribution of waterbirds was affected by disturbance, with more than one-third of the total species and nearly half of the total individuals occurring at the least disturbed point. Species richness was weakly and abundance was strongly correlated to habitat disturbance, but not to habitat quality. Habitat destruction and use of canoes were prominent at the lake. Naxi ethnic fishermen (n=37) were interviewed. They caught 570 waterbirds between October 1999 and March 2000 in fishing nets. An estimation of the total number of waterbirds been trapped on the lake is 6164. Diving species were most susceptible. Conservation measures that should implement immediately include the cessation of habitat destruction, better plan for the development of tourism, a reduction in the number of canoes and zoning of the non-fishing area.     

Social perceptions of the impacts and benefits of invasive alien species: Implications for management

Research on biological invasions has traditionally focused on the ecological component of invasive alien species, either without considering or by considering in a restricted way, the knowledge of the social component. An understanding of the human dimension of invasions is critical to effectively tackle the problems associated with invasive alien species. We distributed questionnaires to evaluate the social perceptions and attitudes of different stakeholder groups affected by invasive alien species in the Doñana social-ecological system (SW Spain). Our analysis served to characterize respondents based on their knowledge and perceptions of the impacts of invasive alien species, and the attitudes toward their introduction and eradication. Hierarchical cluster and principal component analyses identified five categories of respondents, and potential support of eradication programs was assessed using a contingent valuation approach. The five stakeholder groups differed in their degree of knowledge, perceptions, attitudes, and willingness to pay for eradication. The fact that different stakeholders have remarkably different perceptions about the impacts and benefits caused by invasive alien species, and different attitudes toward their introduction or eradication should be considered in any decision-making process regarding their management, particularly when developing appropriate educational and informative programs. Consultation with different stakeholders should also be encouraged from the onset of any decision-making process. In this way, trade-offs involved in IAS management are directly addressed and successful implementation of management practices is facilitated.