RAPID: Effects of a severe El Nino drought on survival, reproduction and population change across tropical songbird species that differ in average survival rates

University Of Montana, Missoula MT

Investigators

Abstract

Extreme climatic events can be stressful on wildlife populations and have important implications for the conservation and management of rare species. The El Niño of 2015-2016 and associated drought in tropical regions was one of the most severe on record. Evolutionary theory predicts that species with long lifespans should reduce their reproduction in response to this type of severe drought more than shorter-lived species. However, this prediction has not been well-tested. Moreover, long-lived species may be at greater risk of extinction under extreme events, in part due to their lower reproduction under stressful conditions. This project leverages data from a long-term field study of tropical bird populations to examine the consequences of the 2015-2016 El Niño on bird survival and reproduction. Understanding the population consequences of extreme climate events is of increasing importance in the face of climate change. Droughts are expected to increase in frequency and intensity with global warming, and are part of El Niño cycles, with particularly strong expression in tropical regions. This project's timely field assessments of survival, reproduction and effects on population size due to this severe climate event will test theoretical predictions and advance understanding of climate stress on bird species and its role in conservation. Much theory has been devoted to predicting life history evolution and responses to extreme environmental events as a function of differential survival probabilities among species, although evidence testing that theory is minimal and conflicting. Ultimately, empirical tests and data are needed from species that experience the same extreme event and that differ in their average survival rates to allow resolution of alternative hypotheses and predictions. This project builds on prior studies conducted with songbirds occupying primary tropical forest at mid-elevations on Mount Kinabalu, Sabah, Malaysia. The new studies will examine the consequences of an extreme climate event for reproductive effort, adult mortality, and population change in the next year for 18 bird species that differ in their average long-term survival probabilities. This work will provide critical tests of theory on life history evolution, population biology, and extinction risk across species that differ in their average adult survival rates, with broad implications for both basic and applied avian biology.