Tropical birds stop breeding for survival

Tropical songbirds have a tactic to survive extreme drought: they stop breeding. Songbirds in rainforests cut back on their breeding to survive drought, according to a study. The scientists found that species with longer lifespans were better able to cope with this environmental instability than previously thought.

With record heat waves on the rise in parts of the planet and biodiversity threatened by human encroachment on habitats, the key question is the ability of animals to adapt to these increasingly harsh conditions.

Drought will become more common due to climate change, the researchers say, forcing birds to compromise between reproduction and their own survival as additional energy is required to produce eggs and feed chicks, even as food becomes scarce.

But a study published in the journal Nature Climate Change found that rather than trying to manipulate the demands of new offspring in harsh environmental conditions, most of the songbird species studied chose to reduce their reproduction during times of drought.

The study used data from 38 species in Venezuela and Malaysia over 17 years of field research, including a period of drought in each country. Reproduction was found to have declined by an average of 36 percent in 20 Malaysian species and 52 percent in 18 Venezuelan species. In birds with a longer lifespan, the greatest slowdown in reproduction was observed during periods of drought.

«Overall, species that experienced a significant reduction in breeding during the drought experienced higher survival rates,» co-author James Mouton of the University of Montana told AFP. «This was surprising as we expected the drought to reduce survival in all species.»

Birds with shorter lifespans, which found it more difficult to restrict breeding, either continued to breed or reduced reproduction only marginally. But they were also less likely to survive.

Drought is just one aspect of climate change that could pose a potential threat to bird populations. Other risks need to be considered, especially habitat degradation or fragmentation. This study offers an exciting contribution to understanding animal population dynamics under environmental stress, but does not change the fundamental importance of habitat availability for species survival.