Climate change has driven population declines and distribution shifts
Rising temperatures and other recent changes in climate have significantly impacted species’ populations. Although warming has increased the abundance of some adaptable species in temperate regions, it has driven declines in many more species. It also creates distribution shifts to higher latitudes or altitudes, which has already led to significant changes in the composition of bird communities.
Temperature changes explain the declines in endemic bird populations in Mexico
The gains and losses of endemic bird species from sampling points across Mexico in recent decades have been influenced mainly by temperature change. Substantially more endemic species have been lost from particular locations than gained.
Species are shifting their ranges polewards
Long-term studies in Europe and North America show that many species are shifting their distributions northwards. Elsewhere, the picture is a little more complicated, with birds in Australia shifting their distributions in multiple directions.
Rising temperatures are forcing montane species to move to higher altitudes
Many montane species are shifting their ranges upslope to track suitable climate, particularly in the tropics. But there is considerable variation in responses: some studies show a significant portion of species showing no changes or shifting to lower elevations - likely due to changes in rainfall patterns.
Warm-adapted species dominating bird communities
The Community Temperature Index reflects the relative composition of warm- and cool-adapted bird species in Europe. It shows that during 1990-2008, there was a shift of communities to warm-adapted species owing to the increasing abundance and arrival of warm-adapted species and decreasing abundance and local extinction of cold-adapted species. These shifts, however, happened slower than the changes in temperature across Europe during this period.