Climate change threatens breeding birds

Climate change threatens breeding birds - Max Planck Institute of Animal Behavior

Tree swallow. Early breeding birds of the species run the risk of losing their chicks because of increased risk of poor weather conditions (MPI of Animal Behavior/ Shipley)

Birds risk starvation in bid to ‘keep pace’ with climate change

Surviving on a warming planet can be a matter of timing—but simply shifting lifecycle stages to match the tempo of climate change has hidden dangers for some animals, according to new research from the Max Planck Institute of Animal Behavior and Cornell University.

The study, published in PNAS, has uncovered drastic consequences for birds that are breeding earlier in lockstep with earlier starts of spring: chicks hatching earlier face increased risk of poor weather conditions, food shortages and mortality. The researchers, who examined decades of data on weather, food availability and breeding in Tree Swallows, say that the timing of when to breed and when food is available is becoming decoupled for some animals—highlighting the complexity behind how organisms respond to climate change. “Simply moving dates earlier to track climate change isn’t necessarily risk free. Riskier conditions earlier in the year can expose animals to unintended consequences when responding to bouts of unusually warm spring weather,” says Ryan Shipley, postdoctoral fellow at the Max Planck Institute of Animal Behavior and first author on the paper.
In recent years, studies have raised concerns about whether or not species can adapt, or “keep pace” with climate change. Particular emphasis has been placed on phenology—the timing of life cycle events such as breeding and migration—and the importance of adjusting this to track rising temperatures and earlier arrivals of spring. But the authors say that breeding earlier may place animals at greater risk of exposure to inclement weather events that tend to occur more frequently earlier in the year. They found that Tree Swallows had been advancing breeding by three days every decade for the last 30 years, but earlier-hatching offspring were at greater risk of exposure to inclement weather, which in turn reduced the availability of the flying insects they rely on for food.