A warming climate could cause baby birds to go hungry

Some species of birds are facing a “ticking time bomb” because climate change is set to disrupt traditional interactions between various animals, causing their young to go hungry, a team of experts warns.

As the climate warns, birds like great tits that depend for their survival on stable sources of food in spring might end up going hungry because those sources of food might not be readily available.

In the end, they could even go extinct, says Emily Simmonds, an associate professor at the Norwegian University of Science and Technology’s Department of Biology. Simmonds is an author of a paper that demonstrates that changes to the supply of larvae in spring can greatly affect great tits, a small bird with a fairly wide range, and other species of birds.

Several species of birds need an abundant supply of larvae for their newly hatched young in spring, and if the larvae supply peaks earlier than normal because of warmer weather, hatchlings might wind up with too little food during a critical stage in their lives.

If spring comes earlier than normal, trees begin to erupt in leaves earlier too, causing larvae that feed on these leaves to hatch earlier. “When the climate changes, the interactions between different species changes too,” says Simmonds, who teamed up with researchers from the University of Oxford to map out the effects of  different climate scenarios on the supply of food for birds like great tits.

Great tits can respond to such changes in the behaviors of their prey, but only up to a point. “An earlier larvae hatch can be advantageous for the great tits whose young also hatch earlier in the spring. This advantage can be transferred to the next generation of birds, which can in turn become early birds,” the scientists explain.

“For this advantage to persist, however, the great tits have to evolve fast enough and be flexible enough to keep up with the genetic variation in their prey,” they add.

If there is a lag of three weeks or so between when larvae and birds hatch because of warming weather, the results could be catastrophic for bird hatchlings.

“Once predator phenology lagged behind prey by more than 24 days, rapid extinction was inevitable, despite previously stable population dynamics,” the scientists write. “Our projections suggest that current population stability could be masking a route to population collapse, if high greenhouse gas emissions continue.”

In the worst-case scenario, whole populations of great tits will simply disappear by the end of the century, Simmonds warns. “This could happen even if great tits also modify their behavior more quickly in a rapidly changing environment,” she says. “The larvae might be changing even faster than the great tits.”