In most cases, the changes are so subtle we scarcely notice them.
At Savannah River Site, where some of the nation's best ecologists keep a close watch on our changing world, the changes are easier to see.
Researchers from the University of Georgia's Savannah River Ecology Lab unveiled data in this month's Proceedings of the Royal Society B showing that salamanders and frogs have shifted their breeding periods over the past 30 years.
Remote wetlands found mainly in the Southeast typically attract such creatures for breeding periods staggered throughout the year.
The SREL scientists discovered that the timing of this migration for four specific species has changed significantly in recent years, with two of the fall breeders migrating weeks later, and two winter breeding species weeks earlier than they did at the beginning of the study. Delayed and advanced breeding may be related to warmer fall/winter temperatures over the years.
Co-author David Scott, a research assistant at the SREL, has helped conduct the study for 27 of its 32 years.
"These data are some of the best in the world for examining how species may respond to a changing climate," he said in a synopsis of the findings distributed by Georgia. "Observing that species respond differently is a start toward predicting how environmental change may affect this group of animals in the decades to come. But there is still a great deal we don't know about how their habitats might change."
Co-author Whit Gibbons, professor emeritus in Georgia's Odum School of Ecology, said the studies in an area known as Rainbow Bay began in 1978 and have been recognized as the longest ongoing amphibian field study in the world. The findings are part of a broader network of changes that, while gradual, may someday prove significant.
Nearly a decade ago, another SREL scientist -- Robert Kennamer -- documented that even the colorful wood ducks that thrive in Southern swamps aren't immune from changes linked to Earth's most disrupting environmental phenomenon.
After studying the small waterfowl for two decades he learned their breeding season had shifted to a full month earlier than it was in the 1970s.
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