Summary An estimated 19% of the world’s 9,856 extant bird species are migratory, including some 1,600 species of land- and waterbirds. In 2008, 11% of migratory land- and waterbirds were classed by BirdLife International as threatened or near-threatened on the IUCN Red List. Red List indices show that these migrants have become more threatened since 1988, with 33 species deteriorating and just six improving in status. There is also increasing evidence of regional declines. Population trend data show that more Nearctic–Neotropical migrants have declined than increased in North America since the 1980s, and more Palearctic–Afrotropical migrants breeding in Europe declined than increased during 1970–2000. Reviews of the status of migratory raptors show unfavourable conservation status for 51% of species in the African–Eurasian region (in 2005), and 33% of species in Central, South and East Asia (in 2007). Land-use change owing to agriculture is the most frequently cited threat affecting nearly 80% of all threatened and nearthreatened species. However, while agricultural intensification on the breeding grounds is often proposed as the major driver of declines in Palearctic–Afrotropical migrants, some species appear to be limited by the quantity and quality of available habitat in non-breeding areas, notably the drylands of tropical Africa. Forest fragmentation in breeding areas has contributed to the declines of Nearctic–Neotropical migrants with deforestation in non-breeding areas another possible factor. Infrastructure development including wind turbines, cables, towers and masts can also be a threat. Over-harvesting and persecution remain serious threats, particularly at key migration locations. Climate change is affecting birds already, is expected to exacerbate all these pressures, and may also increase competition between migratory and non-migratory species. The conservation of migratory birds thus requires a multitude of approaches. Many migratory birds require effective management of their critical sites, and Important Bird Areas (IBAs) provide an important foundation for such action; however to function effectively in conserving migratory species, IBAs need to be protected and the coherence of the network requires regular review. Since many migratory species (c. 55%) are widely dispersed across their breeding or nonbreeding ranges, it is essential to address the human-induced changes at the wider landscape scale, a very considerable challenge. Efforts to conserve migratory birds in one part of the range are less effective if unaddressed threats are reducing these species’ populations and habitats elsewhere. International collaboration and coordinated action along migration flyways as a whole are thus key elements in any strategy for the conservation of migratory birds.

http://www.globalraptors.org/grin/researchers/uploads/302/kirby_et_al._2008.pdf

Key conservation issues for migratory land- and waterbird species on the world's major flyways

Southeast Asia (SE Asia) is a known global hotspot of biodiversity and endemism, yet the region is also one of the most biotically threatened. Ecosystems across the region are threatened by an array of drivers, each of which increases the probability of extinction of species in a variety of ecosystems. These issues are symptomatic of the issues that face the global tropics; however, with around 4 billion people in the wider region and the associated pressures on biodiversity, this region may be under some of the greatest levels of biotic threat. Deforestation rates in SE Asia are some of the highest globally, additionally it has the highest rate of mining in the tropics, around the greatest number of hydropower dams under construction, and a consumption of species for traditional medicines which is a threat to biodiversity globally. In this review, the greatest threats to regional biodiversity in the SE Asian region are discussed. Tree-plantations and deforestation represent one of the most imminent threats, and some countries have already lost over half their original forest cover (i.e., the Philippines, parts of Indonesia), with projections of as much as 98% loss for some regions in the coming decade. Hunting and trade represent a significant threat as demand stems not only for food, but also for medicine, for ornamentation, and as a status symbol. Mining represents a frequently overlooked threat, as the Asian region is one of the greatest exporters of limestone and various minerals globally, and the cost of this to biodiversity is not only through the direct loss of areas for mines, but also through the development of roads that further fragment the landscape, the leakage of heavy metals, and the destruction of limestone karsts, which represent global endemicity hotspots. Reservoir construction, wetland drainage, fires, pollution, invasive species, disease, and finally climate change are also considered. Once each issue has been discussed, the overall prognosis of regional biodiversity and priority actions to protect SE Asian biodiversity in the future is discussed.

https://esajournals.onlinelibrary.wiley.com/doi/pdf/10.1002/ecs2.1624

Understanding the drivers of Southeast Asian biodiversity loss

We re-assessed the population size and trend of 52 species and 75 taxa of shorebirds that occur in North America by reviewing published papers, soliciting unpublished data, and seeking the opinions of experts. New information resulted in changing population estimates for 35 of the 71 taxa that could be compared directly to the estimates published in 2006; from this comparison, 28 estimates increased and seven decreased. Almost all of the increases (88%) were the result of more comprehensive surveys being conducted or re-analyses of existing data rather than actual increases in numbers. Retaining the previous estimate was almost always due to a lack of new information. Recent trend analysis indicates that many shorebird populations have stabilized in recent years after large declines during the early 1980s and mid-1990s. Although many shorebird populations listed as threatened or endangered by the U.S. and Canadian governments have increasing population trends, none have reached recovery targets. Information on population trends remains virtually unknown for 25% of the shorebirds occurring in North America, and surveys are needed to determine the state of these populations.

https://www.allaboutbirds.org/bbimages/lb/pdf/Andres-2012-North-American-Shorebird-Population-Estimates.pdf

Population estimates of North American shorebirds, 2012

Detecting coherent signals of climate change is best achieved by conducting expansive, long-term studies. Here, using counts of waders (Charadrii) collected from ca. 3500 sites over 30 years and covering a major portion of western Europe, we present the largest-scale study to show that faunal abundance is influenced by climate in winter. We demonstrate that the 'weighted centroids' of populations of seven species of wader occurring in internationally important numbers have undergone substantial shifts of up to 115 km, generally in a northeasterly direction. To our knowledge, this shift is greater than that recorded in any other study, but closer to what would be expected as a result of the spatial distribution of ecological zones. We establish that year-to-year changes in site abundance have been positively correlated with concurrent changes in temperature, but that this relationship is most marked towards the colder extremities of the birds' range, suggesting that shifts have occurred as a result of range expansion and that responses to climate change are temperature dependent. Many attempts to model the future impacts of climate change on the distribution of organisms, assume uniform responses or shifts throughout a species' range or with temperature, but our results suggest that this may not be a valid approach. We propose that, with warming temperatures, hitherto unsuitable sites in northeastern Europe will host increasingly important wader numbers, but that this may not be matched by declines elsewhere within the study area. The need to establish that such changes are occurring is accentuated by the statutory importance of this taxon in the designation of protected areas.

Climate change causes rapid changes in the distribution and site abundance of birds in winter

We estimated the size of 30 defined populations of geese wintering in the Western Palearctic (including five released or reintroduced populations of three species). Fourteen populations were accurately estimated from almost full count coverage or robust sampling and ten were well estimated based on more than 50% of their total being counted. An estimated 5.03 million geese wintered in January 2009, up on 3.10 million in January 1993. Only two populations numbered less than 10,000 birds (Scandinavian Lesser White-fronted Goose and Svalbard/Greenland Light-bellied Brent Goose, the former being critically small within restricted range). Eighteen populations numbered 10,000–100,000, eight 100,000–1,000,000 and the largest 1.2 million individuals. Of 21 populations with known longer term trends, 16 are showing significant exponential increases, 4 are stable and one declining. Amongst these same populations, five are declining since the 1990s. Long term declines in productivity were found in 7 out of 15 populations. Amongst most of the 11 populations for which data exist, there were no  significant long-term trends in annual adult survival. Improved monitoring, including demographic, is required to retain populations in favorable conservation status.

/pdf/current-estimates-of-goose-population-sizes-in-western-2dbspapnvs.pdf

Current estimates of goose population sizes in western Europe, a gap analysis and assessment of trends

This publication is a compilation of current knowledge of the numbers, distribution and movements of one of the most remarkable groups of birds in the region covered by the African-Eurasian Migratory Waterbird Agreement (AEWA) Long-term waterbird count data have been combined with an extensive literature review, especially published results of bird ringing and national bird atlases, to produce maps showing the population boundaries that are used as a basis of the conservation of these species The maps are supported by informative species accounts that highlight the movements, population status and conservation of waders in the AEWA region

A.T.F. Helmink

Papers

An atlas of wader populations in Africa and western Eurasia

Waterbird Population Estimates - Fourth Edition