Almost half of the world’s bird species are now in trouble, with many facing imminent extinction. BirdLife first started documenting the status of birds and the threats they face exactly 100 years ago. As a result, birds are better known than any comparable group of organisms and are seen as credible gauges of more general ecosystem degradation and collapse
The latest State of the World Survey from BirdLife International, along with its affiliate BirdWatch Ireland, offers us “the most concerning picture yet of the future of avian species and, by extension, of all life on Earth”.
Main causes of decline
Birds are susceptible to a range of threats. The main threats currently affecting the greatest number of globally threatened bird species are agricultural expansion and intensification (1,026 species, 73%), logging (710 species, 50%), invasive and other problematic species (567 species, 40%) and hunting (529 species, 38%), while climate change is already a significant threat (479 species, 34%) and will pose even greater future challenges.
These threats cause declines in bird populations through a variety of mechanisms. The most significant is habitat conversion and degradation (1,336 species, 95%). Other mechanisms cause direct mortality of individuals (862 species, 61%) or indirectly affect populations by reducing reproductive success rates (510 species, 36%) or increasing competition (134 species, 10%). The vast majority of species (90%) are affected by more than one threat, and many of these threats are interconnected – a clear example of this is climate change and deforestation increasing the risk of extreme wildfires.
Some key figures from the report:
- The IUCN Red List data shows 49% of bird species globally (5,412) have declining populations, 38% (4,234) have stable populations while just 6% (659) are increasing and 6% (693) have an unknown population trend.
- 73% of globally threatened birds are impacted by crop or livestock farming, wood and pulp plantations or aquaculture. There has been a 57% decline in common farmland birds in Europe since 1980.
- Seabirds are one of the world’s most vulnerable groups of birds, with 30% of species considered globally threatened (19 Critically Endangered, 34 Endangered and 58 Vulnerable), a further 11% listed as Near Threatened, and 57% of species are known to be in decline.
- Collisions with buildings, particularly windows, are a significant cause of avian mortality in some countries. For example, in the USA, an estimated 365-988 million individual birds are likely to be killed by colliding with buildings each year. In Canada the range is 16-42 million.
- Almost two-thirds of bird species are found in forests globally, and many of these are regarded as forest specialists that would not be found in other habitats. Each year, around 7 million hectares of forest are lost as a result of harvesting for forest products.
- Invasive alien species can also cause populations declines. It is estimated that each year, cats kill 2.69-5.52 billion individual birds in China, 1.3-4.0 billion birds in the United States, 100-350 million birds in Canada, 377 million birds in Australia, and 136 million birds in Polish farmsteads. In Australia, introduced Red Foxes Vulpes vulpes are estimated to kill a further 111 million individual birds annually, of which 93% are native species.
- A total of 436 bird species have been moved to a higher category of threat due to a genuine deterioration in their status since 1988.
An Irish context
The stark national picture in Ireland mirrors global trends.
Over 60% of Irelands regularly occurring birds are in decline – this can be broken down further as 25% of Irish birds show a severe decline and an additional 37% show a moderate decline.
The birds most affected in Ireland are associated with farmlands. Species such as curlew, lapwing, snipe, kestrel, skylark are the fastest deteriorating group of bird species with upland birds and lowland wetland birds also doing very poorly. There are a number of factors leading to the declines of bird numbers in Ireland. Habitat loss and degradation, pollution in our rivers and lakes, use of rodenticide, all make the landscape more inhospitable for birds. For seabird species, the main drivers of decline are overfishing, disturbance caused by people and dogs at both breeding sites of seabirds and wintering sites for waterbirds, plastics in our seas and avian flu. This year has been a particularly bad year for seabird colonies affected by bird flu.
How can we avoid further declines?
- Protect and effectively manage important sites for birds and other biodiversity
- Conserve important sites through community management
- Retain and restore habitats
- Prevent overexploitation and illegal killing of birds
- Minimise impacts of built infrastructure
- Manage invasive alien species
- Tackle fisheries bycatch