5 May 2021

11 spectacular bird migration bottlenecks from around the world

The Wadden Sea in north-west Europe is one of the world's most important hubs for migrating birds © travelpeter / Shutterstock
The Wadden Sea is one of the world's most important migration hubs © travelpeter / Shutterstock
By Dominic Mitchell

Migratory birds move in their countless millions across the Americas, Africa and Eurasia each spring and autumn. These epic journeys often take place on broad fronts, but birds also concentrate at bottlenecks where geographical features funnel them over narrow ocean crossings, or where rich feeding opportunities enable them to rest and build up fat reserves before continuing their journeys. This selection of hotspots underscores the importance of conservation action in the way birds see the world: through flyways.


1. Fraser River Delta, Canada

This vast area near Vancouver is one of Canada’s most important ecosystems for waterbirds, yet it is under heavy development pressure. There is no overarching legal framework protecting the area, so Birds Canada and Nature Canada (both BirdLife Partners) are among those fighting plans for a huge trading port. One-day estimates of at least 500,000 Western Sandpipers Calidris mauri indicate that much of the global population stops over in spring; high counts of Dunlin Calidris alpina and Grey Plover Pluvialis squatarola also represent about 8% and 3% respectively of the North American populations. Autumn counts of more than 100,000 waterfowl are made regularly.


Thousands of Western Sandpipers stop at Fraser Delta en route to their breeding grounds © Tom Middleton / Shutterstock

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2. Cape May, USA

This New Jersey peninsula is a natural funnel for birds migrating at the junction of Delaware Bay and the Atlantic Ocean. Passage in spring involves more than 100 species and 100,000 birds, and is even more significant in autumn with huge flights of birds of prey – notably Broad-winged Hawk Buteo platypterus, Red-shouldered Hawk Buteo lineatus and Sharp-shinned Hawk Accipiter striatus – as well as numerous shorebirds and seabirds, and impressive waves of warblers, vireos, thrushes, sparrows and other passerine migrants.


3. Veracruz, Mexico

Nowhere on Earth is more spectacular for raptor passage. In autumn up to six million birds of prey from eastern, central and western North America converge en route to winter quarters in Central and South America. Almost the entire world populations of Broad-winged Hawk, Swainson’s Hawk Buteo swainsoni and Mississippi Kite Ictinia mississippiensis – numbering up to two million, one million and 200,000 birds respectively – pass through, along with 1.5 million Turkey Vultures Cathartes aura (and many other species) in what has become known as the River of Raptors.


With 200,000 Mississippi Kites, Veracruz is dubbed the "river of raptors" © Dan Rieck / Shutterstock


4. Panama City, Panama

The skyscrapers of Panama’s capital provide an incongruous backdrop to the streams of ‘kettling’ raptors migrating between breeding and wintering ranges. Mudflats near the city are recognised as one of the five most important areas for migratory and wintering shorebirds in the Americas – an estimated 1.3 million pass through in autumn, including globally important populations of Western Sandpiper (32%) and Whimbrel Numenius phaeopus (20%), among others. Panama Audubon Society (BirdLife Partner) spearheaded moves to save the bay’s wetlands from development, leading to protected status being ratified by the country’s Supreme Court.


5. Wadden Sea, north-west Europe

A vast intertidal area shared between the Netherlands, Germany and Denmark, the Wadden Sea is one of the most important hubs for migratory birds in the world, yet it is threatened by fishing, salt mining, gas extraction and climate change. Some 12 million waterbirds breed, pass through or overwinter, including up to 267,000 Red Knot Calidris canutus (Near Threatened). Good numbers of Eurasian Spoonbill Platalea alba breed, and most migrate to Banc d’Arguin in Mauritania, linking these two UNESCO World Heritage Sites on the same flyway. Vogelbescherming Nederland (BirdLife Partner) is working to ensure protection from disturbance, especially at high tide when birds need to roost safely.


12 million waterbirds can be found at the Wadden Sea © Travelpeter / Shutterstock


6. Mediterranean islands

Migrants crossing the Mediterranean rest on islands such as Malta and Cyprus, where large-scale illegal killing remains an issue. BirdLife Partners work constantly to counter such threats, for example by aligning enforcement of anti-hunting laws in Malta with the migration of European Turtle-doves Streptopelia turtur (Vulnerable), a species that has declined by 80% in Europe in the last 30 years, or combating the illegal use of mist nets and limesticks to trap millions of songbirds for the consumption of ‘ambelopoulia’ – a local delicacy in Cyprus.


7. Middle East

Multiple Important Bird & Biodiversity Areas from the Red Sea north to Lebanon and Syria form part of a vital corridor for vast numbers of migrating birds. As many as 1.2 million occur in spring, including globally significant numbers of European Honey-buzzard Pernis apivorus, Black Kite Milvus migrans, Levant Sparrowhawk Accipiter brevipes, Steppe Buzzard Buteo buteo vulpinus and Steppe Eagle Aquila nipalensis (Endangered). BirdLife is leading the Migratory Soaring Birds project, working in 11 countries along the flyway to minimise the negative impact of energy infrastructure such as wind turbines and powerlines. Illegal hunting is also a threat in the northern part of this region.


"Kettling" raptors spiral up out of the mist at Batumi, Georgia ©  Lars Soerink


8. Batumi, Georgia

More than 1,000,000 raptors migrate through the Batumi bottleneck each autumn, over half of them European Honey-buzzards, as well as huge numbers of Steppe Buzzards and Black Kites, among large volumes of other birds of prey. Illegal killing has been problematic but SABUKO (BirdLife Partner) and the Dutch foundation Batumi Raptor Count are deploying various conservation and awareness-raising strategies, including birding tourism.


9. Khao Dinsor, Thailand

Hundreds of thousands of birds of prey of up to 25 species pass through in autumn, making this the premier raptor migration watchpoint in Thailand, and perhaps the entire Oriental region. In autumn 2016, as many as 791,229 raptors were counted. Chinese Sparrowhawk Accipiter soloensis, Black Baza Aviceda leuphotes and Oriental Honey-buzzard Pernis ptilorhynchus are the three commonest species, but Grey-faced Buzzard Butastur indicus, Japanese Sparrowhawk Accipiter gularis and Shikra Accipiter badius can also be very numerous, and other migrants occur.


A depiction of the thriving diversity of shorebirds found at China's mud flats © Richard Allen


10. Yellow Sea coast, China

Most of an estimated 50 million waterbirds depend on the Yellow Sea’s coastal wetlands as a stopover site on migration. Tiaozini and Dongsha shoals, part of the Yancheng Nature Reserve, are hugely important for migratory birds on the East Asian-Australasian Flyway. Among many species, they support almost half of the total population of Spoon-billed Sandpiper Calidris pygmaea (Critically Endangered) and at least 80% of the world population of Spotted Greenshank Tringa guttifer (Endangered). About a sixth of the known global population of Red-crowned Crane Grus japonensis (Endangered) also winters at Yancheng, now protected as a UNESCO World Heritage Site, in part thanks to the lobbying efforts of BirdLife and the RSPB (BirdLife in the UK).


11. Beidaihe, China

This famous Important Bird & Biodiversity Area in north-east China has lost much habitat to development, but has a small reserve and remains important to huge numbers of migrants crossing the Gulf of Bohai in spring and autumn. These include Siberian Crane Leucogeranus leucogeranus (Critically Endangered) and Red-crowned Crane, Spotted Greenshank and Oriental Stork Ciconia boyciana (Endangered). Notable among its concentration of land bird migrants is Yellow-breasted Bunting Emberiza aureola (Critically Endangered), much declined as a result of large-scale trapping in rice paddies, a practice now outlawed but still known to occur in the region.