The National Park Service will mark its 100th birthday on August 25, 2016. What better way to celebrate than to band (and hold!) a warbler in the Great Smokies or to net butterflies in an alpine meadow in the Cascades? These are just two of the citizen science projects anyone can join at national parks across the country. Citizen science also helps the NPS do its job: Data collected by scores of park visitors affords a much broader overview of ecological change than staff could collect alone. Some projects monitor threatened or reintroduced species, while others look at phenology—the relationship between climate and biological phenomena, such as plant flowering and bird migration—an increasingly important field as climate change disrupts linkages between species. The projects below require little or no training and are open to any visitor with a desire to learn and help out. To get started, just check out the websites below and find your nearest park. Keep reading at Sierra.