Flyway Population Research Articles

Trends in the Autumn Passage Numbers of Arctic and Boreal Waders in W Denmark 1964–2017 as a Contribution to East Atlantic Flyway Population Trends

On the East Atlantic Flyway, where mid-winter counts of waterbirds have taken place for half a century, there is still uncertainty about trends in the sizes of several wader populations. For example, extensive breeding bird monitoring in boreal Fennoscandia, long term monitoring of actively migrating (i.e. passing) birds, and mid-winter counts give conflicting results for a good number of species. In this paper we contribute with the results of 54 years of monitoring of actively migrating birds passing Blavandshuk on the west coast of Denmark and just north of the Wadden Sea each year during 30 June – 27 September. The dataset comprises 14,678 observation hours, and 14 wader species with a total of almost 1.5 million individuals migrating south that were selected for analysis. The vast majority of the birds recorded are adults, i.e. without the large annual fluctuations in juvenile numbers caused by year-to-year variations in breeding success. By combining monitoring results from mid-winter counts, the Fennoscandian breeding grounds and monitoring of passing birds in Denmark and Sweden, the overall picture is that most Arctic and boreal wader populations on the East Atlantic Flyway are thriving. Hence, 24–26 populations appear to have been stable, fluctuating or have shown long-term increases; however, one of these populations has shown a decline in recent years. In contrast, 8–10 populations show declines with one of these indicating some degree of recent recovery. Furthermore, two populations have unknown status.

Conservation implications of extraordinary Greater Scaup (Aythya marila) concentrations in the Odra Estuary, Poland

AbstractHuman activities in marine coastal areas may coincide with protected areas for birds. Some of these anthropogenic activities may pose threats, such as gillnet fisheries, which can significantly affect populations of diving birds, especially gregarious species that gather in huge flocks in small areas such as Greater Scaup (Aythya marila). The Odra Estuary (Baltic Sea, Poland) is known for its importance as a wintering site for scaup; it is also used by fishermen using gillnets. Precise tools to determine the distribution and abundance of birds allow evaluation of risks faced by large aggregations. We used kernel density interpolation to estimate the spatial density of scaup in the Odra Estuary in spring 2011. At that time, an extraordinarily high number of scaup (95,400) was recorded, ~73% (63.0–94.5%) of the entire northwest European flyway population. Three variables are particularly important for conserving highly mobile long-distance migrating species: spatial distribution, abundance, and time (season of the year). This event concentrated most of the scaup flyway population in a small space, making the population vulnerable to mass mortality. We also show aggregated data of the spatial distribution of scaup during the 2015–2016 and 2016–2017 seasons to highlight differences in the spatial use of the area between seasons. Vast areas occupied by scaup in 2011 were not used during 2 other studied seasons; this spatial variation may be crucial in conservation planning of this species. Our results are a first step in documenting the spatial distribution of scaup in the Odra Estuary and identifying the potential area of overlap with fishing activity.

Body condition of Eiders at Danish wintering grounds and at pre-breeding grounds in Åland

Breeding Eiders Somateria mollissima in the Baltic/Wadden Sea population have declined in recent decades, and several causes have been suggested. A recent study showed a modest increase in body mass from 2.20 kg by ca. 100 g during winter in Denmark, the main wintering area of the flyway population. This raises the question of whether Eiders could increase their body mass by an additional 200 g during pre-breeding to reach the average body mass of ca. 2.50 kg needed for successful reproduction. We analyzed this question by collecting Eiders at the Danish wintering grounds and pre-breeding grounds at Aland, Finland. Female Eiders increased their body condition (defined as scaled body mass index) from winter to the pre-breeding period, whereas males concurrently decreased in weight. The mean body mass of adult female Eiders was 2.23 kg in late winter, when they initiated spring migration. The mean female body mass at the pre-breeding grounds was 2.44 kg, an increase of 9.4% compared with females at the wintering grounds, while adult males decreased in weight by 3.4%. A decrease in gizzard mass was accompanied by a change in diet from large blue mussels Mytilus edulis at the wintering grounds to the small but more abundant mussels in the gizzard during pre-breeding. We conclude that female Eiders can reach a body mass of ca. 2.50 kg before breeding. Building up body condition for breeding is feasible at Aland; thus, difficulty in acquiring adequate resources for reproduction is unlikely to restrict local population size.

Importance of Natura 2000 sites for wintering waterbirds: Low preference, species' distribution changes and carrying capacity of Natura 2000 could fail to protect the species

Evaluating the species use of protected area networks is of considerable worldwide importance, especially as a feedback for policy-makers and the conservation community. Based on the data of an annual, citizen-science monitoring programme of long tradition (2004–2015), we test the hypothesis that the European Natura 2000 network protects high quality habitats preferentially settled by wintering waterbird species in a central European State (the Czech Republic). We analysed species-specific variables (protection status, flyway population trend and numbers, geographical distribution, and foraging guild) explaining the proportions of numbers in Natura 2000 and individual-species changes in numbers inside and outside Natura 2000. The proportions of numbers in individual species were generally low in Natura 2000 sites. The observed pattern revealed the expected higher preference of protected Annex I species for Natura 2000 sites compared to other species and showed foraging guilds having significant differences in Natura 2000 preference, with high preference in herbivores and fish-eaters and low preference in invertebrate-eaters compared to omnivores. Northern species also showed a high preference for Natura 2000. The predicted prevalence of a higher rate of increase, or lower rate of decrease, inside Natura 2000, indicating that Natura 2000 facilitated the species' distribution changes, was not shown; instead, the positive and negative trends inside Natura 2000 were almost equivalent. We concluded that the low preference for Natura 2000, the distribution changes shifting species outside Natura 2000, and limits to the carrying capacity of the protected network sites, could all make an issue in effectively safeguarding the non-breeding populations of waterbirds. The extension of the Natura 2000 network to facilitate their wintering requirements and distribution changes is therefore a high priority.

Nonbreeding Duck Use at Central Flyway National Wildlife Refuges

Abstract Within the U.S. portion of the Central Flyway, the U.S. Fish and Wildlife Service manages waterfowl on numerous individual units (i.e., Refuges) within the National Wildlife Refuge System. Presently, the extent of waterfowl use that Refuges receive and the contribution of Refuges to waterfowl populations (i.e., the proportion of the Central Flyway population registered at each Refuge) remain unassessed. Such an evaluation would help determine to what extent Refuges support waterfowl relative to stated targets, aid in identifying species requiring management attention, inform management targets, and improve fiscal efficiencies. Using historic monitoring data (1954–2008), we performed this assessment for 23 Refuges in Texas, New Mexico, Oklahoma, Kansas, and Nebraska during migration and wintering months (October–March). We examined six dabbling ducks and two diving ducks, plus all dabbling ducks and all diving ducks across two periods (long-term [all data] and short-term [last 10 October–March periods]). Individual Refuge use was represented by the sum of monthly duck count averages for October–March. We used two indices of Refuge contribution: peak contribution and January contribution. Peak contribution was the highest monthly count average for each October–March period divided by the indexed population total for the Central Flyway in the corresponding year; January contribution used the January count average divided by the corresponding population index. Generally, Refuges in Kansas, Nebraska, and New Mexico recorded most use and contribution for mallards Anas platyrhynchos. Refuges along the Texas Gulf Coast recorded most use and contribution for other dabbling ducks, with Laguna Atascosa and Aransas (including Matagorda Island) recording most use for diving ducks. The long-term total January contribution of the assessed Refuges to ducks wintering in the Central Flyway was greatest for green-winged teal Anas crecca with 35%; 12–15% for American wigeon Mareca americana, gadwall Mareca strepera, and northern pintail Anas acuta; and 7–8% for mallard and mottled duck Anas fulvigula. Results indicated that the reliance on the National Wildlife Refuge System decreased for these ducks, with evidence suggesting that, for several species, the assessed Refuges may be operating at carrying capacity. Future analyses could be more detailed and informative were Refuges to implement a single consistent survey methodology that incorporated estimations of detection bias in the survey process, while concomitantly recording habitat metrics on and neighboring each Refuge.

Why Are Numbers of Mallards (Anas platyrhynchos) Declining In the Northeastern United States? The Possible Role of Reduction In Winter Feeding Sites

ABSTRACT Breeding populations of Mallards (Anas platyrhychos) have declined 38% in the northeastern United States over the past 17 years. One reason for this may be the reduction of a unique wintering habitat, artificial feeding sites. I hypothesize that artificial feeding sites improved over-winter survival and pre-breeding body condition of Mallards and were utilized by a sufficiently large proportion of the northeastern Atlantic flyway population to improve the population's average annual survival and/or fecundity, thereby impacting population dynamics. In Massachusetts, the number of artificial sites where people fed Mallards declined 44% since 1999. Other states do not conduct surveys of feeding sites, but Christmas Bird Counts provide additional data on populations of wintering Mallards. A sampling of urban centered count circles from northeastern states reveal a 48% decline in numbers of Mallards between 1993 counts and those in 2013.

Habitat selection and activities of dabbling ducks during non‐breeding periods

ABSTRACTWestern Tennessee is an important region for waterfowl during non‐breeding periods, supporting >40% of the Mississippi Flyway population of American black ducks (Anas rubripes). Understanding habitat selection and activities of waterfowl during the non‐breeding period is important for directed habitat management on national wildlife refuges and in other wetlands important in meeting regional waterfowl conservation objectives. During November–February 2011–2013, we investigated diurnal habitat selection and activities of dabbling ducks (Anatini) among 5 common wetland types relative to emergent cover, water depth, and energetic carrying capacity (i.e., duck energy days [DEDs]) in western Tennessee, USA. We observed waterfowl daily and sampled food resources monthly at Tennessee and Cross Creeks National Wildlife Refuges. Mallard (Anas platyrhynchos), gadwall (A. strepera), northern pintail (A. acuta), and American green‐winged teal (A. carolinensis) selected moist‐soil wetlands over wooded, aquatic bed, and open water wetland types. Gadwall also selected deeper wetlands containing submersed aquatic vegetation. Foraging was the dominant activity of all dabbling ducks in mudflats and moist‐soil wetlands, and it was also dominant in wooded wetlands for green‐winged teal and gadwall. Deep, open water was avoided by dabbling ducks. Selection of wetland types was negatively correlated with increasing water depth and positively correlated with increasing emergent cover and DEDs. Shallowly flooded moist‐soil and wooded wetlands provide high‐energy foods and dense emergent cover, and are important to a diversity of dabbling ducks during winter. © 2017 The Wildlife Society.

Barr Al Hikman, a major shorebird hotspot within the Asian–East African Flyway: results of three winter surveys

Barr Al Hikman, a large intact coastal wetland in the Sultanate of Oman, is an important wintering site for migratory waterbirds in the Asian–East African Flyway. The last reported systematic survey of the area is from 1990. Here, we present results of three surveys in 2007/2008, 2013/2014 and 2015/2016. Up to half a million waterbirds of 42 species were counted. Shorebirds were by far the most numerous group (>410,000). For 18 shorebird species, numbers wintering at Barr Al Hikman exceeded 1% of their flyway population. Therefore, our results confirm that Barr Al Hikman is still an important wintering ground, not only with respect to the number of birds, but also in terms of species diversity. Furthermore, a comparison with past surveys shows that numbers have tripled since the 1990s. We argue that, taking into account methodological issues, habitat degradation at other wintering sites in the Gulf region of the flyway may be an important factor leading birds to shift to Barr Al Hikman. However, the future of Barr Al Hikman is uncertain: recent rapid urban growth and road construction have drastically changed the Oman coast, and potentially threatening developments are being planned in the area. Therefore, to preserve the Barr Al Hikman area, clear conservation guidelines and actions are needed, and the site deserves to be designated as a Ramsar site.

Flyway population delineation in Taiga Bean Geese Anser fabalis fabalis revealed by multi‐element feather stable isotope analysis

Fundamental to effective management of migratory waterbird populations is an understanding of their flyway delineation. Taiga Bean Geese Anser fabalis fabalis wintering in NW Denmark, Scotland and England are considered to originate from northern and central Sweden, southern and central Norway (‘Western flyway’), those wintering in southern Sweden, NE and southern Denmark are considered to originate from northern Fennoscandia and western Russia (‘Central flyway’), and those wintering in eastern Germany and Poland (which show far less favourable conservation status) are thought to come from western Siberia (‘Eastern 1 flyway’), although evidence to demonstrate this has largely been lacking. Evidence for different natal and moult origins of Taiga Bean Geese was investigated using stable isotope analyses of feathers of four elements (δ2H, δ13C, δ15N and δ34S). There were significant differences in isotopic composition of feathers from Swedish (Central) and German (Eastern 1) wintering populations and those moulting in Sweden in late summer (Western), which validated the three proposed major management flyway units above. The strong continental gradient in the stable hydrogen isotope ratios in precipitation (δ2Hp) across the region was used to assign wintering birds geospatially to natal and moulting origin, indicating separate natal and moulting areas for German (n = 37, from western Siberia) and Swedish (n = 20, Fennoscandia and more western Russia) wintering birds. These results confirm the largely discrete nature of these three flyways and contribute significantly to our ability to deliver effective targeted and appropriate research, monitoring and management actions throughout the ranges of these flyways.

Identifying priority sites and gaps for the conservation of migratory waterbirds in China's coastal wetlands

Many waterbird species, in particularly migratory shorebirds, on the East Asian-Australasian Flyway depend on the intertidal areas of coastal China. In recent years, these habitats have suffered severe shrinkage as a result of wetland loss and degradation. Identifying critical areas for waterbirds and assessing conservation status has become an urgent priority for biological conservation. Based on the criteria used to designate Ramsar sites and East Asian-Australasian Flyway Partnership (EAAFP) Flyway Network sites, a general framework is proposed and applied to identify priority sites in China's coastal wetlands using a comprehensive waterbird survey dataset. Sites priority were evaluated by using appearance of globally threatened bird species, and bid species exceeding 1% of their global or flyway population, and population abundance. Sites priorities were ranked using an “irreplaceability index”. Totally, 110 sites are proposed as priority sites. Considering the strategic importance of China's coastal wetlands for migratory waterbirds, the conservation status of China's coastal wetlands is inadequate to protect these waterbirds. Currently, 67 of the 110 priority sites lie outside protected areas. Some critical habitats for waterbirds are not included in individual protected areas, especially in Jiangsu, Zhejiang, and Hebei provinces. Improved protection of these areas is urgently needed. However, conservation efforts in China's coastal wetlands face numerous challenges. Many important intertidal areas are increasingly threatened by ongoing and future reclamation plans. There is an urgent need to re-consider and limit the reclamation, particularly at critical sites, and put in place conservation measures to protect migratory waterbirds and their habitats.

Body mass change and diet switch tracked by stable isotopes indicate time spent at a stopover site during autumn migration in dunlins Calidris alpina alpina

Birds may change their diet and foraging habitat during or after migration. Dunlins Calidris alpina alpina breed in the tundra of northern Europe and Russia where they feed exclusively on terrestrial prey. However, up to 80% of the flyway population uses the Wadden Sea as their first important staging site on the way to wintering grounds, feeding exclusively on marine prey. Adult birds migrate earlier than immatures and tend to fly non‐stop, whereas immatures may stage for at least a few days en route, mainly in the Baltic region. There they mostly feed on brackish water prey showing similar isotopic values compared to terrestrial prey. When they arrive in the Wadden Sea, dunlin body reserves are depleted and lower than those of individuals that have already staged for several days. We hypothesized that lighter individuals should retain a strong terrestrial isotopic blood signature, while heavier ones should show a stronger marine signature. We found a significant positive correlation between scaled mass index and carbon (δ13C) and nitrogen (δ15N) stable isotopes, reflecting the switch from terrestrial to marine prey during migration. A mixing model revealed differences in isotopic values between heavy and light adults and immatures, respectively, in relation to the isotopic prey signatures. Adults showed stronger marine signals compared with immatures, emphasizing the different modes of migration (i.e. a later departure in immatures) as well as the known spatial segregation of age classes in the Wadden Sea, i.e. adults use tidal flats distant from the shore while immatures use coastal areas influenced by terrestrial carbon sources. The results of this study demonstrate the value of scaled mass index in migratory birds as an indicator of time elapsed after diet switching following migration. Furthermore, this study extents the existing knowledge on the timing of dunlin migration by using an isotopic approach.

Staging Duration and Passage Population Size of Sanderlings in the Western Dutch Wadden Sea

The population of Sanderlings Calidris alba along the East Atlantic flyway has grown considerably during the last decades. Perhaps reflecting this augmented population size, increasing numbers of Sanderling have been reported to stage in the Wadden Sea during spring and autumn migration. Estimates of the numbers of Sanderlings in the Wadden Sea have previously been based on a limited number of counts that were not corrected for the turnover of individuals. In this study, we accounted for turnover using estimates of the probability that individually colour-ringed Sanderlings are still present two days after a sighting. In combination with daily counts during high tide, we estimated the total number of Sanderlings that used the island Griend and surrounding mudflats, in the western Dutch Wadden Sea, during southward passage in 2013 and 2014. We also estimated minimal staging durations of Sanderlings at Griend. Non-moulting birds were significantly heavier upon capture, which suggests that they were refuelling for long non-stop migratory flights. Winter sightings confirmed that the non-moulting Sanderlings winter in sub-Saharan Africa and that the moulting Sanderlings spent the winter in Europe or northern Africa. With an average minimal stay in the western Dutch Wadden Sea of 9 days in 2013 and 12 in 2014, non-moulting Sanderlings stayed for a much shorter time than moulting Sanderlings, which stayed for 32 days in 2013 and 36 days in 2014. Non-moulting individuals were less likely to be resighted between years. Estimates of minimal staging duration are likely underestimates of the true staging duration, and we propose that moulting Sanderlings probably complete their wing moult in the Wadden Sea. We estimated that the total number of Sanderlings using the western Dutch Wadden Sea before migration to European or African wintering areas were 27,546 (95% Cl 22,739–41,449) in 2013 and 22,574 (95% Cl 16,436–46,114) in 2014. This would amount to 11–14% of a total flyway population of 200,000 individuals, representing an amazing degree of concentration for what is regarded as a rather widely and thinly spread shorebird species.

Seeking explanations for recent changes in abundance of wintering Eurasian Wigeon (Anas penelope) in northwest Europe

We analysed annual changes in abundance of EurasianWigeon (Anas penelope) derived frommid-winter InternationalWaterbird Census data throughout its northwest European flyway since 1988 using log-linear Poisson regressionmodelling. Increases in abundance in the north and east of the wintering range (Norway, Sweden, Denmark, Germany, Switzerland), stable numbers in the central range (Belgium,Netherlands,UKand France) and declining abundance in the west and south of the wintering range (Spain and Ireland) suggest a shift in wintering distribution consistent with milder winters throughout the range. However, because over 75% of the population of over 1 million individuals winters in Belgium, the Netherlands, UK and France, there was no evidence for a major movement in the centre of gravity of the wintering distribution. Between-winter changes in overall flyway abundance were highly significantly positively correlated (P = 0.003) with reproductive success measured by age ratios in Danish hunter wing surveys and less strongly and inversely correlated (P = 0.05) with mean January temperatures in the centre of the wintering range, suggesting thatwinter severitymay also contribute to influence survival. However, adding winter severity to a model predicting population size based on annual reproductive success alone did not contribute tomore effectivelymodelling the observed changes in population size. Patterns in annual reproductive success seem therefore to largely explain the recent dynamics in population size of northwest European Wigeon. Summer NAO significantly and positively explained 27% of variance in annual breeding success. Other local factors such as eutrophication of breeding sites and changes in predation pressure undoubtedly contribute to changes in the annual production of young and differences in hunting pressure as well as winter severity affect annual survival rates. However, it seems likely that the observed flyway population trend since 1988 has been mostly influenced by climate effects on the breeding grounds affecting reproductive success and marginally on the winter quarters affecting survival. We urge improved demographic monitoring of the population to better assess annual survival and reproductive success.We also recommend development of an adaptive management framework to remove uncertainties in our knowledge of Wigeon population dynamics as information is forthcoming to better informmanagement, especially to attempt to harmonise the harvest with annual changes in demography to ensure sustainable exploitation of this important quarry species now and in the future.

Migratory behaviour of bird species occurring in critical numbers at Besh Barmag bottleneck in Azerbaijan

SummaryA narrow coastal plain located between the Greater Caucasus and the Caspian Sea was recently discovered to be a major avian flyway through Transcaucasia. Here at the Besh Barmag bottleneck in Azerbaijan an estimated 1.24–1.51 million migrants passed through in autumn 2011 and a further 0.65–0.82 million in spring 2012, elevating this bottleneck to international importance. Furthermore, 34 bird species were observed in numbers in excess of the 1% threshold of world or flyway population in at least one of the observation seasons. Due to the high concentration of these species, any dangers affecting this passage can be threatening at a population scale. This study therefore aims to describe the migratory behaviour of these 34 species and subsequently to identify the dangers involved in passage through the area. Collision with anthropogenic obstacles was regarded as the main threat in the coastal plain. Ten (40%) of the species studied and observed in autumn 2011 were flying at the lowest altitudes and are therefore under threat on migration through the bottleneck due to overhead power lines, buildings, traffic and hunting. Planned infrastructural developments with heights of up to 200 m (e.g. towers, wind farms) pose a future threat for an additional 13 (52%) of the study species observed in autumn, making a total of 23 species that would be threatened. Only two species, Pygmy Cormorant Microcarbo pygmaeus and Grey Heron Ardea cinerea, can be expected to maintain their currently safe passage in future as they migrate mainly above 200 m above ground level. In spring 2012, all 14 (100%) of the species that used the coastal plain as flyway, migrated below 50 m and are therefore imminently threatened by collision. Although birds migrating over the Caspian Sea were concentrated at the lower altitudes, there was no identifiable threat for migrants using this flyway, but hazards can be expected in the oil production areas further south.

Anthropogenic impact on macrobenthic communities and consequences for shorebirds in Northern France: A complex response

Shorebird populations are declining worldwide due to the combined effect of climate change and anthropogenic forcing, the ongoing coastal urbanisation amplifying the alteration of their habitat in both rate and magnitude. By focusing on a highly anthropogenically-influenced region in Northern France, we studied the impact of a seawall construction on wintering shorebird populations through potential alterations in the abundance and availability of their food resources. We concurrently investigated changes in the spatial distribution of muddy-sand beach macrobenthic communities between two periods of contrasting anthropogenic impacts and examined year-to-year trends of wintering shorebirds. Our study reveals that the seawall construction led to a major spatial reorganisation of the macrobenthic communities with a drastic reduction of the muddy-sand community. However, no relation between macrobenthic changes and shorebird abundances was detected. Fluctuations in shorebird abundances appeared to be congruent with flyway population trends. This result suggests that the response of shorebirds to human-induced perturbations is much more complex than expected. While an assessment of potential disturbances induced by coastal engineering constructions is needed, the pathways by which alterations could propagate through an ecosystem are not linear and as such difficult to determine. Ecosystems appear as complex adaptive systems in which macroscopic dynamics emerge from non-linear interactions at entangled smaller/larger scales. Our results confirm that an in-depth knowledge of the local, regional and global factors that influence trends of shorebirds and their habitat use is essential for accurate and effective management and conservation strategies.

Current status of the Dalmatian pelican and the great white pelican populations of the Black Sea/Mediterranean flyway

The Dalmatian pelican (DP) Pelecanus crispus and the great white pelican (GWP) Pelecanus onocrotalus are listed as 'Vulnerable' and 'Least Concern', respectively, in the IUCN Red List. We present an updated estimation of the Black Sea/Mediterranean flyway population status of both species, based on data provided by experts working in all 7 countries of the region where pelicans breed and/or overwinter, who came together at the 1st Workshop on Pelican Research and Conservation in Prespa, Greece. The DP breeding population in the Black Sea and Mediterranean countries increased from 1730�2105 pairs in the years 2000�2010 to 2154�2437 pairs in 2011�2012. Approximately 40% of the Palaearctic breeding population of GWP occurred in Southeast Europe and Turkey. In 2011�2012 the GWP population in this region was estimated to be 4702�5175 pairs, and has remained more or less stable during the last decade. Although all the breeding sites for both species are in protected areas, disturbance at nesting places was considered to be the main threat. Direct persecution and electric power lines still cause occa- sional problems. In deltaic lagoons, erosion and inundation of nesting sites cause breeding failures in DPs, while in inland wetlands large water level fluctuations are a widespread problem. Decrease of fish stocks is a threat, especially in coastal areas. Many stop-over wetlands along GWP migration routes between Southeast Europe and Africa have been seriously degraded or have disappeared, resulting in serious implications for their populations. Conservation needs are listed, but further research is recommended for both species.

Status of Wintering Waterbirds at Selected Locations in China

Abstract. Wetlands are under enormous pressure due to rapid economic development in China. Waterbirds, which depend on wetlands, are therefore facing a dramatic threat. Surveys were conducted in 19 Provinces in the winters of 2011/2012 and 2012/2013. Sites that support internationally important numbers of waterbirds were selected. Seven sites that support 20,000 or more waterbirds and 48 sites that support more than 1% of the global or flyway population of at least one species were found in our survey. Ten (20.8%) of these sites were protected and 10 (20.8%) had no protection. Eight of the 10 unprotected sites were located along coastlines. Of 16 coastal wetland sites, 43.8% were unprotected. The protection of wintering sites of waterbirds should be made a priority and more wetland sites, especially coastal wetland sites, should be protected. Additionally, an intensive site survey should be conducted to gain comprehensive knowledge of the distribution of wintering waterbirds in China to better protect wat...

EU protection is inadequate for a declining flyway population of Black-tailed Godwit Limosa limosa: mismatch between future core breeding areas and existing Special Protection Areas

SummaryThis study analyses whether effective conservation of Black-tailed Godwit Limosa limosa breeding populations in the Netherlands can be achieved through the EU network of Special Protection Areas (SPAs). An internationally important number of pairs of Black-tailed Godwit breeds in the Netherlands but the breeding population is declining steeply and is, in effect, unprotected, as the Netherlands has not designated SPAs for it. To contribute to firmer and more efficient protection of the Black-tailed Godwit, we set out to identify the core areas in the Netherlands where this species is expected to breed in 2020. On the basis of an optimal combination of three main habitat requirements (groundwater level, land-use and openness of the landscape) we identified five core areas in lower-lying (western) Netherlands: Zuidwest Friesland, Waterland, the IJssel delta area, Arkemheen and Eem polders, and Groene Hart. Because these areas are currently not designated for the breeding period of Black-tailed Godwit within the SPA network, the protection of this flagship species of Dutch meadows could be at risk. It seems likely that the Black-tailed Godwit population will continue to decline, with the result that the Netherlands will breach several policy commitments for the conservation of this species.

Managing hunted populations through sex-specific season lengths: a case of the Common Eider in the Baltic-Wadden Sea flyway population

Management of harvested wildlife populations aims to protect species from overexploitation and ultimately extinction, by regulating exploitation towards achievable sustainable levels. However, assessments of impact and sustainability of implemented management actions on a population level are scarce. This study assesses effects of changes in hunting season length imposed on the Baltic-Wadden Sea Common Eider Somateria mollissima population, including differential restriction on hunting of the sexes. The potential impact of these changes on the population was assessed by simple demographic matrix projections. Since the early 1990s, this population has declined at ca. 6.3 % per annum, and the male/female ratio among shot birds has fallen from 3:2 to about 3:1. Concerns in Denmark regarding the conservation status and sustainability of contemporary levels of exploitation resulted in shortening the open season by 44 and 46 days for females and 13 and 15 days for males from the hunting seasons 2004/2005 and 2011/2012 onwards, respectively. These reduced the kill of adult females by 82 %, adult males by 31 %, juvenile females by 58 % and juvenile males by 55 %. The observed reduction in the kill of adult females following both changes in 2004/2005 and 2011/2012 matched the expected changes based on the seasonal distribution of sexes in the bag prior to the change. Post 2004/2005 hunters killed more adult males, but shot markedly fewer juvenile birds than expected. Demographic modelling of the female population showed that the effects of the reduced hunting would correspond to an increase in the annual population growth rate from the previous −6.3 to −3.6 % (post 2004) and −1.6 % (post 2011). The model also predicted that a full ban on hunting female eiders (adults and juveniles) would lead to a positive population growth rate of 0.7 %. Taking into account the conservative model estimates and natural variations in annual breeding success, the implemented changes in sex-specific regulation of hunting may potentially be an effective management tool to halt the decline of the Baltic-Wadden Sea eider population, potentially rendering such levels of hunting sustainable under prevailing conditions.

Optimal management of a multispecies shorebird flyway under sea-level rise.

Every year, millions of migratory shorebirds fly through the East Asian-Australasian Flyway between their arctic breeding grounds and Australasia. This flyway includes numerous coastal wetlands in Asia and the Pacific that are used as stopover sites where birds rest and feed. Loss of a few important stopover sites through sea-level rise (SLR) could cause sudden population declines. We formulated and solved mathematically the problem of how to identify the most important stopover sites to minimize losses of bird populations across flyways by conserving land that facilitates upshore shifts of tidal flats in response to SLR. To guide conservation investment that minimizes losses of migratory bird populations during migration, we developed a spatially explicit flyway model coupled with a maximum flow algorithm. Migratory routes of 10 shorebird taxa were modeled in a graph theoretic framework by representing clusters of important wetlands as nodes and the number of birds flying between 2 nodes as edges. We also evaluated several resource allocation algorithms that required only partial information on flyway connectivity (node strategy, based on the impacts of SLR at nodes; habitat strategy, based on habitat change at sites; population strategy, based on population change at sites; and random investment). The resource allocation algorithms based on flyway information performed on average 15% better than simpler allocations based on patterns of habitat loss or local bird counts. The Yellow Sea region stood out as the most important priority for effective conservation of migratory shorebirds, but investment in this area alone will not ensure the persistence of species across the flyway. The spatial distribution of conservation investments differed enormously according to the severity of SLR and whether information about flyway connectivity was used to guide the prioritizations. With the rapid ongoing loss of coastal wetlands globally, our method provides insight into efficient conservation planning for migratory species.