Bird species numbers plummet

Talking Point

The world’s biodiversity is in a grim state. The global Red List assessments conducted by the International Union for Conservation of Nature (IUCN) show declines in the conservation status of all facets of biodiversity. The latest Living Planet report concludes that populations of mammals,  birds, reptiles, amphibians, and fishes have declined by an average of 69% since 1970. At a broad level, the major causes for these declines are destructive land use, direct exploitation, climate change, pollution, and invasive species. The Global Biodiversity Framework (GBF), adopted in December 2022, pledges to halt biodiversity loss and restore ecosystems. One of its four goals is to halt the human-induced extinction of threatened species. The GBF is one of several commitments that the world’s countries, India included, have made towards the well-being of people as well as the planet. In order to achieve the targets they have set, countries need a way of assessing the health of their biodiversity, but this can be a tremendous challenge. One aspect of biodiversity that has received considerable attention is birds. Birds are everywhere, they can be identified relatively easily, and they have deep cultural significance.  They can also act as indicators of biodiversity as a whole because they are mobile and responsive to change;  contain enough species to show meaningful patterns, their trends generally reflect those of other groups, and they are relatively easily monitored…

Bird species numbers plummet

Arunima Sen Gupta

Around 60 per cent of birds in India have experienced a population decline over the long term of 30 years, says 2023 State of India’s Birds (SoIB) report. Birds occupying open natural ecosystems, such as grasslands, have seen steep declines in numbers. In terms of diet, birds that feed on vertebrates and carrion have declined the most, followed by birds that feed on insects. Birds perform a number of important ecosystem services, aiding in seed dispersal and pollination, as well as acting as predators and scavengers. But around 60 per cent of birds assessed in the report have declined over the long term of 30 years, which conservationists have termed a matter of deep concern. Around 40 per cent were found to be declining currently, over the last eight years.

The findings were captured in the State of India’s Birds 2023 report, which was released on August 25 by a consortium of 13 government and non-profit conservation organizations, and based on 30 million bird sightings. The report identifies 178 birds of high conservation priority which need urgent action plans for their conservation and deeper research to understand the factors leading to their decline. Some of these species include the sarus crane, the Indian courser, the Andaman serpent eagle, and the Nilgiri laughingthrush. Habitat ‘specialists’ are especially vulnerable, while ‘generalists’, or birds that have adapted to a variety of landscapes, have been stable in comparison. Some species, like the ashy prinia, rock pigeon, Asian koel, and Indian peafowl “have increased dramatically” over the years the report finds. Overall, however, the results are grim and call for a re-classification of 14 species by the International Union for Conservation of Nature (IUCN) to its Red List of threatened species.

“We were surprised to see that, even with a more robust statistical analysis, more data, and more observations than last time, bird populations are declining. This indicates it is a more serious problem that we previously realised,” said Rajah Jayapal, a senior scientist with the Sálim Ali Centre for Ornithology and Natural History (SACON), which also contributed to the report. “It is a two way link. The number of declines could be because of declining ecosystem functioning, or resource availability, or habitat decline itself. But one can also imagine consequences in the other direction. The decline in raptors, for example, could result in changes in populations of rodent communities, which may see a boom,” said Ashwin Viswanathan, Research Associate at the Nature Conservation Foundation, one of the organisations that contributed to the assessment. “A lot of this is speculation. We need to find out how ecosystems are adapting to changing bird numbers,” he added.

Birds in open habitats particularly vulnerable: The released report is the second edition of the SoIB, the first of which was released in 2020. The latest report assesses 942 bird species, up from 867 in 2020, and was based on 30 million sightings recorded on the eBird portal by 30,000 citizen birdwatchers. Such citizen science “which may be less or more coordinated, is the only way in which information can be generated for biodiversity assessments at the required scale”, the report says. The declining trajectory of bird populations in India follows global trends, where 48 percent of birds have declined, according to the 2022 State of World’s Birds report. India hosts around 1,350 of the world’s bird species, of which 78 are found only within India. Birds inhabit all kinds of ecosystems, from coasts and wetlands to high altitudes and tropical rainforests. But birds that occupy open natural ecosystems (ONEs), particularly grasslands and semi-arid landscapes, are especially vulnerable, with such species declining by 50 percent, the report says.

A well-known example is the great Indian bustard, which is on the brink of extinction because of land use changes and habitat loss. But there are other species that are seeing steep declines too. “Of particular note is great grey shrike, because it has suffered a particularly worrisome long-term decline of more than 80%. This species and other grassland specialists like chestnut-bellied sandgrouse have done better in regions rich in ONEs compared to the country as a whole, indicating the importance of conserving ONEs,” the report says.

Birds that live in wetlands as well as in wooded areas, such as forests and plantations, have also declined more than generalist species, “indicating a need to conserve natural forest habitats so that they provide habitat to specialists”. Birds feed on a variety of sources, such as meat (vultures and other raptors), fruits and nectar (barbets and sunbirds), seeds (sparrows and doves), and invertebrates (warblers and flycatchers). Bird populations could also be influenced by limited or contaminated food resources. “In India, birds that feed on vertebrates and carrion have declined the most, suggesting that this food resource either contains harmful pollutants or is declining in availability, or both. Strong evidence from other countries shows that agrochemicals lower survival rates in some raptors,” the report says, adding: “We find that birds that feed on invertebrates (including insects) are declining rapidly. This needs to be taken together with recent findings that insect populations worldwide have reduced, and that pesticides are thought to be a main contributor to massive declines in European insectivorous birds.”

Over 40 percent of the world’s insect population has been on the decline and is likely to go extinct in the coming years. Scientists in India suspect similar trends are playing out here, but data is limited. Fruit and nectar feeding birds are doing well, “maybe because these resources are readily available even in heavy-modified rural and urban landscapes,” the study says. The report also notes the widespread decline of both resident and migratory ducks, but says there is little understanding of why this otherwise flocking species is reducing in number. “One of the main recommendations is to support research as much as possible, because the data leaves us with so many unanswered questions. We know certain birds and groups of birds are declining, and we now have information to focus research into why,” said Viswanathan.

Threats and recommendations: Even though India has Protected Areas and laws like the Wildlife Protection Act, which awards special protection for certain species, these measures are not sufficient to stop the declining populations of birds in India, whose ranges span from hundreds to thousands of kilometres. The report locates declining bird populations within eight broad threats, such as environmental pollutants, forest degradation, urbanisation, avian disease, illegal hunting and trade and climate change. The spread of monocultures through commercial plantations or afforestation programmes have reduced biodiversity. “Plantations lack vertical and horizontal vegetation complexity because they maintain even-aged stands of a single tree species for ease of harvest. This usually leads to loss of large-sized trees and reduction in canopy shade and shrubbery,” says the report. The result is fewer bird species occupying these areas compared to rainforest habitats.

Another threat is the expansion of renewable energy infrastructure, such as wind mills. Rotating wind turbines can result in fatal collisions, displacement, or barriers to migration for birds. According to the report, 60 species from 33 families of birds are affected by collisions and electrocution at power lines in India. “Open habitats are the ones which are immediately available for infrastructure, developmental, and renewable energy projects,” said Jayapal. The report comes at a time when India is rapidly expanding renewable energy and changing its forest policies to accommodate more plantations, while granting more exceptions for the diversion of virgin forests. “In the face of diverse developmental pressures, maintaining the size and integrity of natural habitats is crucial. Beyond this, where habitats have degraded over time, restoration efforts will be vital: not planting trees in monocultures, but rather ecological restoration of multiple habitats including non- forest habitats like grasslands,” says the report, adding: “One particular challenge will be to mitigate the considerable negative effects of even small-scale infrastructure such as wind energy, often thought of as ‘green energy’.”

Some of the recommendations made by the report include conducting “targeted, systematic, periodic monitoring of bird populations, using consistent methods, over long periods of time. Moreover, monitoring changes in other factors such as disturbance, climate, and land-use is also crucial to building a deeper understanding.” In 2020, the Indian government announced a 10 year Visionary Protection Plan for the conservation of avian diversity, ecosystems, habitats and landscapes. The Plan outlined steps to be taken in the near, middle, and long term to effectively monitor and raise awareness about bird conservation. The SACON is one of the focal institutes supporting the VPP. According to Jayapal, 17 states and union territories have initiated work on their own VPPs, while five — Uttarakhand, Delhi, Telangana, Andhra Pradesh, and Meghalaya — have completed the process. “By 2030, we expect states to pay more attention to bird conservation issues and work to mitigate priority areas,” he said. Says Viswanathan: “The amended Wildlife Protection Act took into consideration some of the findings from the SoIB 2020 report, and so we’re hopeful that some policy interventions will follow this one. We’re hopeful that a simple intervention, like recognising open landscapes as open, and not allowing plantation and afforestation activities there will be done.”

Native species threatened by human-introduced alien species

In the most extensive study on invasive species carried out till date, the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) in its new publication – the “Assessment Report on Invasive Alien Species and their Control’’ – has found that there are 37,000 alien species, including plants and animals, that have been introduced by many human activities to regions and biomes around the world, including more than 3,500 invasive alien species and that invasive alien species have played a key role in 60% of global plant and animal extinctions recorded. The report, which was released recently, says invasive alien species are one of the five major direct drivers of biodiversity loss globally, alongside land and sea use change, direct exploitation of organisms, climate change, and pollution.

Invasive alien species (IAS) are animals, plants, fungi and microorganisms that have entered and established themselves in the environment outside their natural habitat. IAS have devastating impacts on native plant and animal life, causing the decline or even extinction of native species and negatively affecting ecosystems. The global economy, with increased transport of goods and travel, has facilitated the introduction of alien species over long distances and beyond natural boundaries. The negative effects of these species on biodiversity can be intensified by climate change, habitat destruction and pollution. IAS have contributed to nearly 40 per cent of all animal extinctions since the 17th century, where the cause is known. Meanwhile, environmental losses from introduced pests in Australia, Brazil, India, South Africa, United Kingdom and the United States are estimated to reach over US$100 billion per year. IAS is a global issue that requires international cooperation and action. Preventing the international movement of these species and rapid detection at borders is less costly than control and eradication.

The IPBES released its report following a week-long plenary from August 28th, with representatives of the 143 member States which have approved the report. IPBES is an independent intergovernmental body established to strengthen the science-policy interface for biodiversity and ecosystem services, working in a similar way to the IPCC, which is the UN’s climate science body. The study, which has taken place over a period of four years, has been by 86 leading experts from 49 countries, drawing on more than 13,000 references. The report has noted that the number of alien species (species introduced to new regions through human activities) has been rising continuously for centuries in all regions, but are now increasing at unprecedented rates, with increased human travel, trade and the expansion of the global economy.

“Not all alien species establish and spread with negative impacts on biodiversity, local ecosystems and species, but a significant proportion do – then becoming known as invasive alien species. About 6% of alien plants; 22% of alien invertebrates; 14% of alien vertebrates; and 11% of alien microbes are known to be invasive, posing major risks to nature and to people,’’ the IPBES has said. The report further noted that many invasive alien species have been intentionally introduced for their perceived benefits, “without consideration or knowledge of their negative impacts’’ in forestry, agriculture, horticulture, aquaculture, or as pets. Nearly 80% of the documented impacts of invasive species on nature’s contribution to people are negative. “Invasive alien species have been a major factor in 60% and the only driver in 16% of global animal and plant extinctions that we have recorded, and at least 218 invasive alien species have been responsible for more than 1,200 local extinctions . In fact, 85% of the impacts of biological invasions on native species are negative,” said Prof. Anibal Pauchard, co-chair of the Assessment.

The water hyacinth is the world’s most widespread invasive alien species on land. Lantana, a flowering shrub, and the black rat are the second and third most widespread globally. The brown rat and the house mouse are also widespread invasive alien species. The report said that the annual costs of invasive alien species have at least quadrupled every decade since 1970, as global trade and human travel increased. In 2019, the global economic cost of invasive alien species exceeded $423 billion annually. “These trends are projected to accelerate as the global economy expands, land and seas are used more intensively, and demographic change takes place,’’ the report said. The reduction of food supply, has been cited by the report as the most common impact of alien invasive species. For example, the European shore crab impacting commercial shellfish beds in New England or the Caribbean false mussel damaging locally important fishery resources in Kerala, by wiping out native clams and oysters. The Caribbean false mussel was originally from the Atlantic and Pacific coast of South and Central America, but are believed to have travelled to India via ships, later spreading to estuaries through smaller fishing vessels.

Invasive alien species like Aedes albopictus and Aedes aegyptii spread diseases such as malaria, Zika and West Nile Fever, while others also have an impact on livelihood such as the water hyacinth in Lake Victoria in East Africa led to the depletion of tilapia, impacting local fisheries. The IPBES report has further warned that warming temperatures and climate change could favour the “expansion of invasive species’’. “Climate change is also predicted to increase the competitive ability of some invasive alien species, extending the area suitable for them and offering new opportunities for introductions and establishment. Invasive alien species can also amplify the impacts of climate change. For example, invasive alien plants, especially trees and grasses, can sometimes be highly flammable and promote more intense fires,’’ it said.

The report found that 34% of the impacts of biological invasions were reported from the Americas, 31% from Europe and Central Asia, 25% from Asia and the Pacific and about 7% from Africa. Most negative impacts are reported on land (about 75%) – especially in forests, woodlands and cultivated areas – with considerably fewer reported in freshwater (14%) and marine (10%) habitats . Invasive alien species are most damaging on islands, with numbers of alien plants now exceeding the number of native plants on more than 25% of all islands. Most countries (80%) have included targets related to managing invasive alien species in their national biodiversity plans. Only 17% specifically address the issue in national legislation, although more (69%) include it as a part of legislation in other areas. Nearly half of all countries (45%) do not invest in management of biological invasions.

Way Forward

Changes in land and sea use: The biggest driver of biodiversity loss is how people use the land and sea. This includes the conversion of land covers such as forests, wetlands and other natural habitats for agricultural and urban uses. Since 1990, around 420 million hectares of forest have been lost through conversion to other land uses. Agricultural expansion continues to be the main driver of deforestation, forest degradation and forest biodiversity loss. The global food system is the primary driver of biodiversity loss, with agriculture alone being the identified threat of more than 85 per cent of the 28,000 species at risk of extinction. Harvesting materials such as minerals from the ocean floor and the building of towns and cities also impact the natural environment and biodiversity. Reconsidering the way people grow and consume food is one way of reducing the pressure on ecosystems. Degraded and disused farmland can be ideal for restoration, which can support protecting and restoring critical ecosystems such as forests, peatlands and wetlands.

Climate change: Since 1980, greenhouse gas emissions have doubled, raising average global temperatures by at least 0.7 degrees Celsius. Global warming is already affecting species and ecosystems around the world, particularly the most vulnerable ecosystems such as coral reefs, mountains and polar ecosystems. There are indications that climate change-induced temperature increases may threaten as many as one in six species at the global level. Ecosystems such as forests, peatlands and wetland represent globally significant carbon stores. Their conservation, restoration and sustainability are critical to achieving the targets of the Paris Agreement. By working with nature, emissions can be reduced by up to 11.7 gigatons of carbon dioxide equivalent per year by 2030, over 40 per cent of what is needed to limit global warming.

Pollution: Pollution, including from chemicals and waste, is a major driver of biodiversity and ecosystem change with especially devastating direct effects on freshwater and marine habitats. Plant and insect populations are dwindling as a result of the persistent usage of highly dangerous, non-selective insecticides. Marine plastic pollution has increased tenfold since 1980, affecting at least 267 animal species, including 86 per cent of marine turtles, 44 per cent of seabirds and 43 per cent of marine mammals. Air and soil pollution are also on the rise. Globally, nitrogen deposition in the atmosphere is one of the most serious threats to the integrity of global biodiversity. When nitrogen is deposited on terrestrial ecosystems, a cascade of effects can occur, often resulting in overall biodiversity declines. Reducing air and water pollution and safely managing chemicals and waste is crucial to addressing the nature crisis.

Direct exploitation of natural resources: The recent IPBES report on the sustainable use of wild species reveals that the unsustainable use of plants and animals is not just threatening the survival of one million species around the world but the livelihoods of billions of people who rely on wild species for food, fuel and income. According to scientists, halting and reversing the degradation of lands and oceans can prevent the loss of one million endangered species. In addition, restoring only 15 per cent of ecosystems in priority areas will improve habitats, thus cutting extinctions by 60 per cent by improving habitats. Negotiations at COP15 are expected to focus on protecting plants, animals and microbes whose genetic material is the foundation for life-saving medicines and other products. This issue is known as access and benefits sharing governed by an international accord - the Nagoya Protocol. Delegates at COP15 will be looking at how marginalized communities, including Indigenous Peoples, can benefit from a subsistence economy - a system based on provisioning and regulating services of ecosystems for basic needs. Through their spiritual connection to the land, Indigenous Peoples play a vital protection role as guardians of biodiversity.