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Dossier: the silent chorus – declines in the bird world

  • Written by  Mark Rowe
  • Published in Wildlife
Dossier: the silent chorus – declines in the bird world
14 Oct
Birds are a much-loved component of the natural world, serenading us each morning and filling the skies with life. Yet, like many animals, birds are in decline and it isn’t just the rare, flagship species that are in trouble

During the Covid-19 lockdown, people engaged with nature in the UK and elsewhere in an unprecedented way. The dawn chorus became a regular feature of everyday life for thousands of us. The reality, however, is that in the UK alone, 40 million fewer birds took part in that dawn chorus than did so 50 years ago.

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Across the planet, 40 per cent of bird species are in decline. In North America, there are 2.9 billion fewer birds taking wing than was the case during the 1970s. Some countries in Africa and Asia have reported even more catastrophic declines. One in nine bird species in Africa face a high risk of extinction in the wild, with populations of threatened birds such as vultures and grey parrots having declined by 90 per cent in the past four decades, according to BirdLife International.

The World Conservation Union (IUCN) reports that 14 per cent of all the world’s bird species are included on its Red List of species at risk of extinction. Almost 60 years after Rachel Carson’s seminal book on the impact of pesticides on birds and wildlife in general, there are fears we’re on the cusp of another silent spring.

‘On a geographical level, on a global, regional or UK level, the severity of the crisis in birds and biodiversity in general is real,’ says Martin Harper, director of conservation at the RSPB. The evidence, as Harper implies, is irrefutable. Birds, because of their beauty and visibility, are subject to some of the most authoritative animal studies on the planet. The definitive records have been compiled by BirdLife, which published its first comprehensive assessment in 1988 and has documented the deterioration of bird populations ever since. BirdLife says that at least 40 per cent of bird species worldwide (3,967) have declining populations, compared with just seven per cent that are increasing (653). These declines are taking place in both temperate and tropical regions, and in habitats as varied as farmland, forests and wetlands.

‘It’s always challenging for people to understand the scale of what’s going on,’ says Kevin Gaston, professor of biodiversity and conservation at the University of Exeter. ‘It’s a question of how to convey to people just how vast the shifts are. Things become a bit clearer when you do the calculations about the sheer scale of the losses.’

Ten per cent of the world’s Atlantic puffins are located in UK watersTen per cent of the world’s Atlantic puffins are located in UK waters

The Red List Index, issued by BirdLife and the IUCN, reveals that over the past 30 years, more bird species have slipped closer to extinction. Three species are thought to have been lost since 2000: Spix’s macaw disappeared in Brazil in 2000, the last two wild Hawaiian crows in 2002 and the last known poo-uli, also from Hawaii, died in captivity in November 2004.

This isn’t a particularly new phenomenon: over the past 500 years, we’ve lost at least 161 bird species – an extinction rate far higher than the natural background rate. Just as alarming is the fact that current declines don’t represent falls from a healthy level of population. ‘Conservation studies only really started in the 1970s but the declines started well before then,’ says Gaston. ‘When we say a species has declined by 25 per cent over the past 50 years, the point is that the baseline of the 1970s was already much, much lower than the original, healthy population numbers.’

Particular groups of birds are being hit harder than others, including cranes (73 per cent of crane species are in decline), Old World vultures (68 per cent), albatrosses (68 per cent) and parrots (29 per cent). Many globally threatened bird species, such as the Pacific Island pigeon, have tiny populations and very small ranges, restricted to remote mountaintops, oceanic islands or forest patches.


Yet declines aren’t restricted to a few charismatic species. Around the world, once-familiar, formerly common species are coming under threat of extinction, often as the result of large-scale exploitation and habitat degradation. In the USA, starlings have dwindled by 49 per cent – 83 million birds – since the 1970s. ‘Much conservation has focused on the loss of rare birds, but the most significant thing of recent years is that common birds – starlings, sparrows – have lost very large numbers,’ says Gaston. ‘They are not about to go extinct tomorrow, but they are symptomatic of the huge scale of losses.’

Gaston points out that human nature means that we generally tend not to notice there’s a problem until it has become full blown. ‘We don’t pay attention when we see two rather than three robins in the garden,’ he says. ‘It’s only when we don’t see them at all that we notice they’re not there.’

The UK, too, has many once-common birds that are now threatened. Sometimes, as Tris Allinson of BirdLife International points out, the clue’s in the name. ‘The common pochard and common eider are now in the same category as the snow leopard,’ he says. ‘Curlews and lapwings have the same trajectories in population trend as some of the headline birds you hear about.’



Atlantic puffins in the UK
The Atlantic puffin is one of the most iconic bird species currently at risk of extinction. With a low reproductive rate, puffins are highly vulnerable to changes in their natural environment. Of their world population, 90 per cent of Atlantic puffins are found in Europe; ten per cent – or about 450,000 individuals – are in the seas around the UK. This map shows the distribution of this much-loved sea bird in British waters during the breeding season, as mapped in the European Seabirds at Sea database. Alongside the puffin density over sea, this map also shows Important Bird Areas identified by BirdLife International as vital for the species’ protection. The example of the Atlantic puffin demonstrates how protected areas must not only be established on land and coastal areas, but also need to include areas at sea, far beyond the coastline. [Map: Ben Hennig]

The message is clear: declines in species not on the IUCN Red List offer just as powerful a warning. ‘When I was growing up, the focus was on charismatic island species – large-boned, flightless birds, such as the kakapo in New Zealand,’ says Allinson, who is the lead author of BirdLife’s definitive 2018 State of the World’s Birds report. ‘The dodo is the poster child, if you will, of those species. But species that were once commonplace are now in freefall.’ Allinson points to the yellow-breasted bunting, which is found from Finland to Japan but has tumbled its way down through the Red List categories to the point that it’s now considered to be critically endangered. 

‘Red Listed birds with a high chance of extinction carry a lot of symbolism,’ says David Noble of the British Trust for Ornithology. ‘But declines are happening in quite common birds – skylarks are still quite common but they are declining. Even if the bird still has high numbers, when they begin to decline rapidly it can take a long time to turn things around.

‘We are good at tackling flagship species – they are the ones that we get good funding for, everyone likes a comeback story,’ he continues. ‘You can engage the psyche of huge masses of people through these. But the wider decline of so many species is warning us that this is not enough.’


Saving the cuckoo requires scientists to look beyond the borders of the countries within which it breeds. Breeding cuckoos in the UK have declined by 70 per cent over the past 25 years, but only in the past few years, thanks to the efforts of the British Trust for Ornithology (BTO), has it been discovered that UK cuckoos mainly winter in and around the Congo rainforest and Gabon. The routes they take to reach the Congo are also increasingly understood and these highlight some of the threats the birds face. Satellite-tagged cuckoos followed by BTO researchers use two different routes from the UK to reach their wintering grounds: one through Spain and a second through Italy and the Balkans; all of the birds make their spring return via the western route.

Birds that used the western route through Spain faced higher levels of mortality during the autumn migration. The BTO believes that climate change and changing land use in southern Spain may be having an impact on these birds, reducing foraging opportunities and the abundance of the hairy caterpillars on which they feed. These caterpillars fuel the cuckoos’ migration and if a bird can’t find sufficient food in these stopover areas, then crossing the Sahara becomes perilous. 

Land-use pressures in sub-Saharan Africa are also affecting the ability of birds to forage and thrive during the northern winter. Pressures include the clearing of forest to create space for oil palm plantations. This change in land use appears set to accelerate.


The ubiquity of bird species under pressure tells us that they face diverse, multiple and often interrelated threats, including farming practices, logging of forests, the use of insecticides and other pesticides, hunting for sport and food, as well as the illegal wildlife trade and disease. Land clearance for agriculture is often preceded by deforestation or wetland drainage.

‘There are pressures wherever we look,’ says Gaston. ‘We are simplifying habitats, removing resources, chopping down trees and replacing them with fields, pastures, farmland. That, in turn, means places with high bird densities become places with low bird densities as opportunities to exist become narrower and narrower.’

Climate change overshadows and exacerbates all of these issues, affecting a third of globally threatened bird species. So far, the 21st century has been warmer than the previous three centuries (since the 1980s, average UK temperatures have increased by nearly 1°C). Recent common-bird population trends in Europe and North America show a strong and consistent correlation with climate change, according to BirdLife International. Almost a quarter of the 570 bird species studied globally have already been negatively affected – either in numbers or in distribution – by climate change, while only 13 per cent have responded positively. For the remainder, the impact remains uncertain. Species negatively affected include the snowy owl, which is still widespread throughout the Arctic tundra, but is experiencing a rapid decline. Meanwhile, the depletion of fish through overfishing and climate change has caused rapid declines in widespread and much-loved seabirds such as the Atlantic puffin and the black-legged kittiwake; both are now considered to be vulnerable to extinction.

The elephant in the room, however, say experts, is us. ‘The primary driver is a growing human population consuming more and putting undue pressure on the natural world,’ says Harper. ‘This is expressed through habitat destruction, invasive species and pollution.’

Cranes have been hit particularly hard – 73 per cent of crane species are in declineCranes have been hit particularly hard – 73 per cent of crane species are in decline

Allinson agrees. ‘Humans have been having a disproportionate impact on other species since we moved out of Africa,’ he says. ‘Nearly all the problems affecting birds are human in origin. Logging intensifies hunting activities; climate change makes the problem of invasive species worse.’

These drivers affect birds in ways that we’re still trying to understand, according to Gaston. ‘At the species level, a loss of habitat – trees or oceans – plays out differently, whether it is the temperature being too warm, or not enough insects to coincide with the timing of migration,’ he says. ‘Unpicking how these pressures interact and overlap, which are the most important to a particular species – that is hard to do.’

Habitat loss, however, is the key factor, affecting 74 per cent of birds, according to BirdLife. The area of Earth’s land surface given over to agriculture has increased more than six-fold over the past 300 years, from under six per cent in 1700 to more than 38 per cent today. The increase of farmland and the corresponding loss of hedgerows and woodland has an impact on 1,091 globally threatened birds (74 per cent of all such species). This continues at a rapid pace, particularly in the tropics, where demand for commodities such as coffee, cocoa, sugar, palm oil and soya has seen land use change. In Europe and the USA, land that has long been farmed has become even more intensively industrialised and less bird friendly. As Harper puts it, this creates the ‘biggest challenge’ as it involves competition between the need to grow food and the need to allow the natural world to function. 


It’s an odd question: why do birds matter? Self-evidently they have their place in the food chain and within a range of ecosystems, but it seems that birds have the power to touch us in a way that few other classes of organisms do. We value birds in many ways: culturally, artistically, philosophically and economically. Throughout history, many of our most enduring cultural symbols have been birds, from Horus, the Egyptian god of creation, often depicted as a falcon, to Quetzalcoatl, based on the resplendent quetzal, who dominated the traditions and beliefs of the Maya and Aztecs of Central America. ‘There is something extraordinary about birds,’ says the RSPB’s Martin Harper. ‘It’s the nature of their flight, their songs, their migration. They lift our spirits, they are just there, we see them every day. Imagine if we couldn’t.’

Loss of birds is also a serious problem for humanity at a utilitarian level, for it has an impact on food production, carbon storage and climate change. ‘There are great, unknown consequences about what happens when you remove a species from a complex food system. If we don’t address the challenge, nature will bite us back,’ says Harper.

So severe are the pressures facing UK birds that the RSPB says it has effectively had to triage certain groups of birds that it deems are in most need and for which measures can be put in place. Consequently, the RSPB has focused particularly on UK upland birds such as the hen harrier and dotterel; sub-Saharan migrants such as the cuckoo, flied flycatcher and wood warbler; and seabirds, including UK populations of birds such as the kittiwake and the albatrosses of the Southern Hemisphere. ‘We have seabird populations that are important internationally, thanks to our coastlines,’ says Noble, ‘but they are affected by oil, exploitation and climate change. They have a vulnerable life strategy – they have to live close to the sea, be able to raise chicks and be able to find food. If anything breaks in that chain, such as having to travel further for food, they are in trouble – and that’s what’s happening.’

A major problem for UK farmland birds is the changing growing seasons. The introduction of winter sowing has removed the winter stubble that birds such as yellowhammer, reed bunting and skylark rely on for seeds on which to feed. ‘It’s the loss to birds of what farming sees as unproductive areas – the semi-natural habitat of ditches and hedgerows that are taken out to increase the size of fields,’ says Noble. ‘Farmland birds are struggling because farmland is such a big part of our countryside.’

Globally, insecticides and other pesticides are also having a detrimental impact on farmland birds. According to BirdLife International, one recent study from the USA found that migrating white-crowned sparrows exposed to concentrations of neonicotinoids lost a quarter of their body mass and fat stores. The neurotoxin also impaired their migratory orientation.

Farmland birds aren’t the only UK category on a downward trend. Upland birds – curlews, redshank, snipe, golden plover – are all struggling, as are swifts, which can require up to 100,000 insects a day when feeding chicks. Between 1996 and 2015, the UK Red List of birds of concern increased from 36 to 67 species and some, such as the merlin, a small bird of prey, returned to the Red List. Increasingly severe declines in breeding populations has led to listings for curlew, nightingale, pied flycatcher, whinchat, grey wagtail, mistle thrush and Slavonian grebe. The wheatear, a migratory moorland bird with a distinctive black ‘robber’ mask, is also in trouble, having declined by 48 per cent between 1995 and 2018.

A red-legged kittiwake at St George Island, AlaskaA red-legged kittiwake at St George Island, Alaska

Other factors include invasive alien species, which threaten 578 (39 per cent) globally threatened bird species. Birds on remote islands are particularly susceptible, with three quarters of globally threatened species on oceanic islands affected by invasives, typically introduced predators, which often target chicks and eggs. Rats and cats have had by far the greatest effect, threatening the survival of hundreds of bird species worldwide, such as the Galápagos petrel. 

Cultural elements also take a toll. Hunting and trapping put 517 (35 per cent) species at risk. Songbird-keeping is a deeply entrenched pastime in many parts of Southeast Asia and the trade involves hundreds of species and millions of individual birds, to the extent that the bird trade is now recognised as the primary threat to many of the region’s species. A 2015 survey of Jakarta’s three main bird markets by the organisation TRAFFIC counted 19,000 birds from 206 species in just three days.


Despite the negative picture, all is far from lost. Conservation efforts are making a real and lasting difference. At least 30 bird species, including the northern bald ibis and Seychelles warbler, would have gone extinct during the past century without the targeted actions of conservationists.

Such targeted approaches give hope, says Allinson. ‘Personally, I think all of the solutions that are out there are not really that difficult. They just require implementing. For each threat, there are good examples of how an issue is being dealt with. We are capable of turning around endangered species with concentrated action. We can bring a species back from the brink – it’s scaling that up that is more problematic.’ 

‘What we are best at is managing habitat where specific bird species are breeding,’ adds Noble. ‘We create protected habitats for birds that are quite rare and these can be particularly effective. We’ve seen this work for the bittern. We can do it at the field level, but how do you roll that out on a bigger scale, persuade enough farmers and landowners?’

Farmland Birds Europe

Farmland birds in Europe
The negative impact of farming practices on birds is widely acknowledged. The creation of large-scale monocultures has changed the habitats of many species around the world. Even the European Union’s much-criticised Common Agricultural Policy has adapted to the unintended consequences of its earlier incarnations and the EU has, in recent years, added measures intended to enhance farmland biodiversity. This map series demonstrates how much of a challenge remains. Shown here are changes in population abundance and diversity of common bird species in farmland across Europe compared to the situation in the year 2000. Few countries have shown improvements, highlighting the need to implement a more targeted biodiversity strategy if these goals are to be considered a more serious part of the EU’s agricultural policy in the future. [Map: Ben Hennig]

The costs required to essentially restore global biodiversity – not just birds but other threatened classes – and to establish the necessary protected areas has been put at around US$80 billion a year. ‘That sounds a lot,’ says Allinson, ‘but that’s how much Americans spend on lottery tickets every year, or how much the planet spends on pet food. The return on that investment has been put at US$80 trillion. We actually achieve an awful lot with relatively little money. If you factored investment up you could significantly address the problems.’

Even simple measures can achieve a great deal, says Gaston, such as letting a corner of a field grow wilder. But he also emphasises how this micro approach has to go hand in hand with addressing wider landscape problems. ‘We can slow, reduce or reverse the extinction rate, but we need to provide landscapes that do more than just stop things getting worse,’ he says.

‘If you provide opportunities for wildlife to return, it will – you get all sorts of surprises. Things show up

that you didn’t anticipate.’

On a grander scale, Noble hopes for the establishment of protected flyways for migratory species, which provide or safeguard suitable habitat for migratory birds at either end of their journey from Africa to Europe, as well as at their stop-off points en route. ‘In Africa, they are losing habitat to development,’ he says. ‘Some birds can cope with the scrubby farmland that remains after forests are taken out, but others require rainforest.’ The expansion of the Sahara is a concern, as climate change influences the network of protected sites and demands that birds fly farther between stops. Birds also face the threat of shooting for ‘sport’ as they fly over Malta and Cyprus. ‘Getting stopover sites established where these birds can fatten up is important,’ says Noble. ‘We can work with local governments and partners. We need much bigger areas. These benefit more than birds – they benefit humans, too, because of the ecosystem services they bring.’


Vultures are an integral part of the global food chain, scavenging the bodies of dead animals, removing germs and replacing them with nutrients, yet they are both much maligned and declining. The main driver of the decline of Asian vultures was identified more than 20 years ago, when post-mortem tests revealed high levels of diclofenac, an anti-inflammatory drug given to cattle. When the drug is metabolised, it becomes deadly to carrion feeders such as vultures. The RSPB’s Harper stresses the importance of understanding the causes of decline. ‘The decline of Asian vultures has been shocking,’ he says, ‘but we needed the science in order to understand what was driving it. If we had assumed it was a landscape problem, rather than a veterinary one, we would have missed the issue.’

Africa’s eight vulture species, meanwhile, have declined by a collective 62 per cent during the past 30 years. Many are dying after eating carcasses laced with pesticides placed by farmers hoping to kill lions and other predators, with the problem particularly acute in Botswana, Kenya and Zimbabwe. Another threat is that of local belief systems. In Nigeria, the birds’ tremendous eyesight has been their undoing: birds’ brains are ground to snuff by witch doctors who believe that consumption of vulture body parts can enable humans to see into the future. BirdLife Africa is working to raise awareness and advocacy against belief-based use of vultures in Nigeria and has helped to establish vulture-safe zones that cover 250,000 hectares in Zambia.

The current focus of flyways is on nightingales, cuckoos and turtle doves (whose UK numbers have dropped by 95 per cent over recent decades). Cuckoos seem to suffer higher mortality if they fly over Spain than if they fly across Italy, but either way, they end up in the deep forests of the Congo. They spend a couple of months there, then head to Sierra Leone and return back up to Europe, more slowly than they headed south in the autumn. Yet even if birds such as the nightingale and cuckoo can cope with scrubland rather than primary forest, it doesn’t mean they cope well. ‘They face the same problems they do in the UK with the increase in farmland,’ says Noble.

The problems facing turtle doves, however, also need to be addressed closer to home. ‘We know the decline in the UK is down to changing farming practices,’ says Harper. These changes mean fewer weeds around for the birds to find insects to feed their chicks. ‘They are just not finding enough food, so you don’t get the numbers fledging in the UK. We have worked with farmers, who have been brilliant, to help us provide habitats that support the birds. But during migration, they are subject to unsustainable hunting. There has to be a moratorium.’ Although changes in land-use practices are affecting the birds’ African wintering grounds, Harper warns: ‘The buck stops with us – the breeding season is simply not productive enough.’


While individual projects can address the problems faced by a particular species, these operate within a wider challenge. ‘There are more systemic challenges around agriculture,’ says Harper. ‘How do we provide enough food for the world’s population in a sustainable way? It seems we can produce enough food already to feed the planet but we have one billion people going to bed hungry and another one billion who are obese. The problems lie in distributing food.

‘This is a multi-decadal issue,’ he continues. ‘Success takes time and we need to be proactive and persistent. Unless we really deal with these ultimate drivers, we will fail in our objective of saving the natural world.’

Harper also points out how even those who believe they are passionate supporters of conservation need to rethink their everyday lives. ‘A lot of the impacts of our behaviour are unseen. We have to be inspirational; conservationists need to communicate these issues with flair.’ Production of the world’s greatest commodities, palm oil, soy, cocoa and others, all have huge impacts on the natural world, he says. ‘But their impacts can be invisible. The plastic issue took hold because people could see it with their own eyes. But logging of forests to produce cocoa plantations happens out of sight.’ Simple measures, such as choosing a chocolate bar made by communities that don’t cut down forests, can make a significant difference to a species of tropical songbird in West Africa, he says. 

The approach of many governments – seeing the issue as addressing either nature or the economy – is misplaced, says Noble. ‘The two are linked. It’s not a question of nature, or education, health and the economy. Nature keeps all of these going. That may be holistic and sound idealistic but that is how it works. We can fight our small battles in our local patch but we also need to address issues on a global scale.

‘A lot of what we do is successful but it always feels as though we are on the edge,’ he continues. ‘We have to keep pushing and pressuring – otherwise we worry that economic considerations will trump everything.’

Allinson is also exasperated by the argument that a choice must always be made between human development and conservation. ‘There’s a widespread feeling in conservation that many of the problems facing birds are just so huge, intractable and deep-rooted that tackling them will be just too difficult,’ he says. ‘The argument goes that with finite resources we need more food for human population growth and so you can’t really help wildlife. A lot of people have now shown you can do both.’

An adult curlew on moorland in Yorkshire during the nesting season      An adult curlew on moorland in Yorkshire during the nesting season

In this regard, Gaston is hopeful that Covid-19, despite its horrors, may have changed people’s attitudes. ‘It’s been really noticeable how much more people have appreciated nature,’ he says. ‘They’ve realised that access to the countryside is a good thing. Much of what happens next depends on how people interact with this, and their understanding of the link between the environment and physical and mental well-being. You will not get environmental growth played out across the landscape without engagement at every level, from local communities to landowners.’

Allinson agrees that Covid-19 has also highlighted the consequences of an approach of wantonly exploiting global resources. ‘What happened was essentially inevitable – conservationists predicted that if you behave the way we do towards the natural world, the transmission of a zoonotic disease was inevitable. You can wonder what it is about humanity that we never seem to get a grasp ahead of time – we always seem to react in the moment.’

Yet Covid-19 has also highlighted something more positive: that governments, or at least many of them, are able to respond rapidly and effectively to an immediate threat. ‘Hospitals have been built in weeks, money has been found to furlough people,’ Allinson says. ‘When the impetus is there, things can be done. A lot of people pay lip service, but there is a greater recognition. At government level, businesses, the world of finance – they now listen to us seriously.

‘The problems are not insurmountable,’ he concludes. ‘There is enough hope and plenty of examples of where things are working. The talk in the wake of Covid-19 is of building back better. I hope this will be a turning point in the recognition of science. We can’t give up. This really is the last chance.’


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