NEBRASKAland Magazine is dedicated to outstanding photography and informative writing with an engaging mix of articles and photos highlighting Nebraska’s outdoor activities, parklands, wildlife, history and people.
Issue link: http://mag.outdoornebraska.gov/i/644631
MARCH 2016 • NEBRASKAland 53 N obody likes winter, really. Especially those animals that rely on the sun for body heat. As winter approaches, amphibians and reptiles in Nebraska find shelter to wait out the harsh cold until the heat returns. But before the warmth of spring arrives, even while winter is still toying with us, there are some that emerge so early from their winter slumber that snow is often still on the ground. And so the question we all want to ask is "Why get up if you don't have to?" The hands-down winner of the "first to wake up every spring" award is the small-mouthed salamander. All salamanders are cold-tolerant, and in fact they prefer cooler to warmer temperatures. Here in Nebraska as winter draws to a close in late February and early March, these little gray salamanders make an annual pilgrimage to shallow pools filled with melted snow. Many of the pools are still covered with ice, but the salamanders slide beneath the ice into near freezing water temperatures. Not long after the small-mouthed salamanders slip beneath the ice, the first frogs of the season begin to chorus … often from the same ponds. In early to mid-March, in nearly every pool, ditch or other shallow water habitat formed from snow melt or early rains, there will be boreal chorus frogs singing their songs. Snow is often still on the ground, continuing to melt into the pools. But when you hear what sounds like fingers running across the teeth of plastic combs coming from every puddle of water you see, you can rest assured that spring is not far off. Why? For what reason does this seemingly irrational behavior sound like a good idea? Reproduction, of course. The perpetuation of the species. Pools formed by melted snow are not permanent. The small- mouthed salamander must court, mate and lay eggs, and the eggs must hatch and develop before the pools dry out. If they don't, there will be no recruitment for the year. So to improve success, salamanders get into the breeding ponds as early as possible. Similarly, the boreal chorus frogs must breed and tadpoles must metamorphose before pools dry. But these little frogs have an extra element incentivizing them to get an early start: competition. In March they are the only frogs using the pools. But as spring approaches, more frogs and toads will encroach upon their breeding ponds, where competition ensues at multiple levels. Chorusing time, space to lay eggs and food for tadpoles all become scarce resources as more frogs start to breed in the pools. But the boreal chorus frogs will have reduced their competition with their late winter head start. By the time other frogs show up, chorus frog tadpoles will already have hatched and started developing, thus obtaining resources before the competition begins. In fact, when some species are just starting to breed, chorus frogs have already metamorphosed and left the water. Getting out of bed early for the sake of improved reproductive success is a good strategy, but there are some risks and trade-offs. Late season cold spells can refreeze breeding pools, killing breeding adults, eggs and tadpoles. Dry winters can result in no breeding pools at all, and without a backup strategy a full year of reproduction could be lost. These animals have developed these adaptations as a result of harsh conditions on the Great Plains. But as climates change, the future of these species may depend on their ability to adjust their strategies. ■ Early Risers Why do some reptiles and amphibians wake up before others? By Dan Fogell, Herpetologist, Southeast Community College Small-mouthed salamanders prefer cooler to warmer temperatures. Boreal chorus frogs breed early in the spring.