Some songbirds react to droughts by making fewer babies, a new paper reports.
The findings showcase how climate change, which is making droughts more frequent and intense, could impact songbird reproduction. Most species of plants and animals are going to feel the effects of a warmer climate on their ecosystems, as food webs and precipitation levels are bound to adapt to new conditions. But songbirds in particular seem to change their reproductive patterns in response to droughts.
Bird babies, just add water
“Here we show that tropical songbirds in the New and Old Worlds reduced reproduction during drought, with greater reductions in species with higher average long-term survival,” the authors write.
“Behavioural strategies of longer-lived, but not shorter-lived, species mitigated the effect of increasing drought frequency on long-term population growth.
Drought can be a tricky thing to handle in the wild, as it makes both food and water scarcer, thus requiring more energy to secure. Reproduction is already a very costly process. Drought can make it unattainable, or at least risky, for both plants and animals.
Tropical songbirds seem to take a drastic approach when faced with long periods where water is scarce: they dramatically reduce their rate of reproduction. The study surveyed 18 species in Venezuela and 20 in Malaysia for over 17 years, which included a period of drought in each country. All in all, the birds reduced their rate of reproduction by 52% and 36%, respectively. But this does seem to help the birds better cope with drought.
“In general, species that greatly decreased breeding during the drought (that is, longer-lived species) experienced increased adult survival,” co-author James Mouton, of the University of Montana, told AFP.
“This was surprising as we were expecting droughts to reduce survival to some degree in all species.”
Longer-lived birds curtailed their reproductive behavior the most during dry periods, while those with short lifespans made small to no changes. Long-term modelling of these trends suggests that birds with longer lifespans will be more resilient to drought.
It makes sense for some species to have instinctual mechanisms that protect them from drought. Past research has shown how arthropods in Australia react “during a longer‐term shift toward drought” as well as a rainy event. The issue here is that climate change is poised to make droughts more frequent and longer, making such compensatory behavior more common. It will also put greater pressure on species and their habitats while they’re already reproducing less.
The paper “Longer-lived tropical songbirds reduce breeding activity as they buffer impacts of drought” has been published in the journal Nature Climate Change.