Bigger is often better, at least when it comes to being an animal. That's why new evidence regarding salamanders in the Eastern United States is so alarming. "Bigger animals in general tend to get more mates, they have more offspring, they tend to win in any sort of battles -- whether it's courtship or territorial behaviors," Dr. Karen Lips, associate professor of biology at the University of Maryland, recently told BBC News. Lips and a team of researchers found that salamander specimens caught in the Appalachian Mountains are on average 8 percent smaller than those caught from the same habitat in the 1980s. Lips began capturing salamander species in 2007, picking up on the research efforts of Professor Richard Highton, now retired, who collected salamander species up and down the East Coast from 1957 to 2007. Highton's collection of thousands of salamanders has remained preserved for scientific study at the Smithsonian Institution's Museum Service Center in Suitland, Maryland. Lips began comparing her newer specimens to Highton's exhaustive collection in an effort to find out why population numbers throughout the East Coast were declining. In doing so, Lips showed that salamanders were getting smaller and smaller over the years, and that no obvious disease or habitat loss was to blame. "Body size is a really, really important factor for most animals," explained Lips. "When you shrink that affects what can eat you, what you can eat, how successful you're going to be at reproducing. Bigger is generally better." Lips collaborated with other scientists to get a better understanding on why exactly salamanders were shrinking. The most likely culprit: global warming. As temperatures heat up, so do the animals' metabolisms. Lips and her colleagues determined that modern salamanders are using 7 to 8 percent more energy to survive on a day-to-day basis.