Deep within the passageways that twist and turn at Mammoth Cave National Park the acoustics can be incredible. There is no background noise other than the shuffling feet, soft voices of visitors, and, in some passages, the running or dripping of water. On December 6 those sounds will fade into the background when the park hosts its annual Cave Sing to celebrate the coming holiday season.

As a recent court case illustrates, people convicted of poaching animals in national parks face stiff penalties. Two North Carolina men who pleaded guilty to killing a bear on the Blue Ridge Parkway were given prison time to reflect on the error of their ways.

If you thought round gobies and zebra mussels were scary invaders of the Great Lakes, brace yourself for the arrival of Asian carp, a voracious fish that could decimate the lakes' native fisheries.

They're not particularly glamorous, but the renovations under way to the visitor center at Wind Cave National Park will provide utility efficiencies, enhance fire protection, and protect the park's museum collections with better climate control.