An annual rite of spring has been noted in Yellowstone National Park: the year's first sighting of a grizzly bear on the move.

Work has begun at Yellowstone National Park to cull 600-900 animals from the park's bison herds, a process deemed necessary to keep the bison population in check but which is highly controversial.

Severe winter weather, geothermal sources, and short construction seasons top the list of issues Yellowstone National Park managers encounter when planning major projects, such as replacement of the Yellowstone River Bridge between Tower Junction and the park's Northeast Entrance. While replacing the bridge won't happen overnight -- it's expected to take three construction seasons -- park engineers believe they have come up with the appropriate plan, and your thoughts on it are welcomed.

Continuing a series of national parks quizzes and trivia, contributing editor Rebecca Latson wants you to try your hand at Quiz #3 to see just how much park knowledge you possess before checking the answers at the bottom of the article.