Populations of cooperatively breeding birds are buffered against annual variation in precipitation and temperature

Louis Bliard , Michael Griesser, Ryan R. Germain

Cooperative breeding is a reproductive system wherein other than parents care for offspring. It has been suggested to provide advantages in harsh and unpredictable climates. Support for this idea stems from detailed population studies, or phyla-wide comparative studies, but both approaches are insufficient to assess the demographic benefits of cooperative breeding. Here, we use abundance time-series from 1843 populations of 505 bird species coupled with local climate to show that population growth rates of family-living and cooperatively breeding species are less sensitive to annual variation in temperature and precipitation. Moreover, larger species are demographically more buffered than smaller ones, while climatic sensitivity displays latitudinal gradients. Our study demonstrates that cooperative breeding is a reproductive strategy increasing the demographic resilience of populations in the face of climatic variability. Ultimately, these findings reveal the demographic mechanism enabling cooperative breeders to successfully inhabit a wide range of environments, including harsh and unpredictable ones.