When researchers looked at the effects of recent extreme drought in the Sierra Nevada, they expected to find the large-scale death of trees would cause bird numbers to decline. Instead, they found many of the species increased — apparently in response to favorable conditions that emerged from the warming climate.
An extensive drought struck the region from 2013 to 2016, resulting in the widespread death of pine trees by bark beetles. Researchers from Point Blue Conservation Science wanted to see what effect the death of these trees would have on the birds that depend on them. For many of the species, they found, whatever negative impacts the dead trees had were offset by positive effects from climate conditions.
They published their findings in the journal Ecological Applications.
“Birds respond rapidly to changes in both habitat and climate conditions and thus are good indicators of the ecological effects of a changing climate, which may include warmer temperatures, changing habitat conditions, and increased frequency and magnitude of extreme events like drought,” they wrote.
Looking at the influence of temperature, water deficit and tree mortality on 45 bird species, researchers used climate models to predict the effect of climate change on the bird community through 2050.
Overall, they found, the total number of birds in the study area increased during the drought. Models predicted similar responses to future warmer climate conditions. Nearly half the species responded positively to temperature increases Only 20 percent declined. The lack of water resulted in declines in a third of the species while another third increased. Researchers found many species that benefited from warmer temperatures, however, were also sensitive to tree mortality and lack of water, suggesting future drought or habitat change could offset positive responses to temperature.
The biologists found that the loss of tree cover, while widespread, had only modest short-term effects on the birds and could have long-term benefits for woodpeckers and other birds that use dead trees for cavity nesting.
While climate change is expected to have negative impacts for many species, and long-term impacts for these birds are unknown, researchers found many bird species to be surprisingly resilient.
“Future climate conditions may not have a universally negative effect on biodiversity in the Sierra Nevada,” they concluded.
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