Torpor season: What happens in Lowcountry lakes during cold snaps

What a winter we are having here in the Lowcountry. It was forecasted to be absolutely frigid (and even snowy) the last weekend in January and beyond. Reading by a warm fireplace, sipping on a mug of coffee or hot chocolate, or snuggling up in a cozy bed all sound like fine ways for us humans to deal with the excessively cold weather we’ve been having lately. But what are the wild outdoor critters to do with temperatures like these? 

Most readers are probably familiar with the word "hibernation." Several species of South Carolina bats hibernate in caves, mines and tunnels in the upstate, according to the South Carolina Department of Natural Resources. Another hibernator in the state is the black bear, but our temperatures are warm enough – especially down near the coast – that full hibernation is not really required here. 

Cold-blooded creatures like reptiles and amphibians "brumate." This is something like hibernation, but while it's characterized by slowed respiration and reduced activity, the animals don't quite hibernate. Some may mostly bury themselves in mud or gather together in dens. But one might still see alligators or snakes out sunning during some of our warmer winter days, even if they are usually out of sight. 

But what about fish? How do they survive in our lakes and ponds? For starters, water changes temperature much more slowly than air does. For our short-term blasts of truly cold weather, Daniel Island's lakes and ponds don't get nearly as cold as our lowest air temperatures. And due to their salinity, it's rare to see our (generally brackish) lakes or ponds frozen over. However, sustained water temperatures below 45 degrees or shorter periods in the 30s will begin to kill both our saltwater fish and the mullet, bass, bream and other freshwater species in our ponds. 

More frequently than dying, though, our fish enter "torpor." Torpor is a state of reduced physiological activity. Everything just slows down. This helps the fish conserve energy and requires less oxygen and food. Generally, that's good, but it does create some problems. Perhaps the biggest problem with torpor is birds. Fish elude birds with quickness and agility. Hungry pelicans, cormorants, egrets and herons work hard to catch them. When the fish can barely move they are quite easy to catch. 

Birds are warm-blooded. If anything, cold weather means they need more calories, not less. It's a bit of a "perfect storm" for the fish. While they are slow and least able to avoid their avian predators, the birds are in abnormally high need of calories and more active than usual with their fishing. There can be crazy feeding frenzies when the conditions are right. If the water is cold enough, birds can practically grab a meal with no effort at all. These feeding free-for-alls might include many species of birds diving (pelicans), swimming (cormorants) or scooping up fish while flying, floating, sitting on the shore, or even hovering (gulls, egrets and herons).  

Smythe Lake has seen its share of these scenes as cold weather dropped the lake's water temperatures below its winter norms. This writer didn't realize until long after taking the photos that a few shots from one of last year's bird parties even included some opportunistic raptors. What appear to be two red-shouldered hawks can be seen diving into the melee.  Whether they were pursuing dropped fish or their fellow birds is unclear, but it seems more likely they were attracted by and to the birds. 

So now if you come across one of these chaotic scenes during a stretch of cold weather you will understand what's going on. There may be no "free lunches," but at times the price of grabbing a meal at the local lake gets pretty low. Once word gets out and the number of patrons grows large, the fish are being pursued underwater, snatched from the surface and targeted from the air, all when they are least able to flee. One can almost see the flashing "Today's Special: Torpor Fish!" message on the sign at some waterfront seafood restaurant as flocks of hungry diners arrive for the "early bird special."