July 12, 2013
Climate Change Has Resulted In More Predation On Mosquito-Eating Birds
April Flowers for redOrbit.com - Your Universe Online
According to the Centers for Disease Control and Prevention (CDC), 286 people were killed in the US in 2012 by West Nile virus, which is carried by mosquitoes. Many bird species eat these mosquitoes and other insects that can be agricultural pests. Rising temperatures are threatening these wild birds, including the Missouri-native Acadian flycatcher, by making snakes more active and hungrier.
University of Missouri biologist John Faaborg led a new study which urges farmers, public health officials and wildlife managers to be aware of complex indirect effects of climate change in addition to the more obvious influences of higher temperatures and irregular weather patterns.
"A warmer climate may be causing snakes to become more active and seek more baby birds for food," said Faaborg, professor of biological sciences in MU's College of Arts and Science. "Although our study used 20 years of data from Missouri, similar threats to bird populations may occur around the world. Increased snake predation on birds is an example of an indirect consequence that forecasts of the effects of climate change often do not take into account."
Cooler temperatures in the heart of Missouri's Ozark forest usually make snakes less active than those found in the edge of the forest or in smaller pockets of woodland. During abnormally hot years, however, even the deep interior of the forest increases in temperature. Warmer temperatures make cold blooded snakes more active and increase their need for food. Prior studies used video cameras to discover snakes are major predators of young birds.
During the last two decades, research by Faaborg and his colleagues has shown fewer young Acadian flycatchers (Empidonax virescens) and young Indigo buntings (Passerina cyanea) survived during hotter years. One reason for this, the study suggests, is an increase in snake activity.
The findings of the study, published in Global Change Biology, are based on data collected over 20 years of fieldwork performed by Faaborg, his colleagues and former students.
"Low survival in the Ozark nests harms bird numbers in other areas," Faaborg said. "Birds hatched in the Ozark forest spread out to colonize the rest of the state and surrounding region. Small fragments of forests in the rest of the state do not support successful bird reproduction, so bird populations in the entire state depend on the Ozarks."