More species are projected to decline under climate change than are likely to benefit
Although some species are projected to benefit from climate change because their distributions and populations are expected to expand, there are likely to be many more species that lose out. Worryingly, many threatened species are likely to become more imperilled, while most of the species projected to be impacted according to recent studies were not previously recognised as under threat. This implies that the challenge for conservation will grow substantially.
Some species have traits that make them particularly susceptible to climate change
More than 2,300 bird species worldwide are highly vulnerable to climate change because they have a combination of high sensitivity to its impacts (e.g. through their dependence on other species), low ability to adapt (e.g. by dispersal) and a high exposure to changing climate.
Climate change will increase the number of species under threat
Globally, one quarter of ‘highly climatically vulnerable’ (based on their biological characteristics) are already listed as threatened by BirdLife International on the IUCN Red List, while only 1% of climatically threatened or vulnerable bird species in North America have been identified as of concern on the Red List. This suggests that climate change will increase the number of threatened species and affect those already in trouble. The magnitude of these effects will be related to the degree of climate change.
There are projected to be more losers than winners under climate change
Results from studies across different regions show that, on average, there are projected to be more than twice as many species whose populations and distributions may decline under climate change than the number that are expected to increase. Generalist species are typically likely to increase in population and range, while specialist species are expected to decline. The magnitude of these declines is expected to increase with the severity of climate change.
Species richness of South African bird communities is projected to decline across different habitats
While some species of South African birds are projected to expand their distributions under climate change, more are projected to contract, leading to average reductions of 30-40% in species richness of South African bird communities in grassland and fynbos by 2085. This is likely to influence the functioning of ecosystems, especially since important pollinators such as Malachite Sunbird (Nectarinia famosa) are projected to decline, on average, more than other species.