Justin Kerwin, senior park ranger, candles a common goldeneye duck egg to check its intubation stage at the Chena River Lakes Flood Control Project in North Pole, Alaska. Working with officials for the U.S. Fish and Wildlife Service and U.S. Army Corps of Engineers – Alaska District park rangers at the Chena Project, students track bird species that use the nest boxes and tag chicks that hatch. The students must monitor and time their visits to the boxes to ensure they tag and catalog each chick before they leave the nest as there is only about a 24-hour window to attach a small metal web tag to each duckling before they leap out of the box and head for the nearest water body. (U.S. Fish and Wildlife Service courtesy photo)