Nature lovers have long tracked the timing of certain events — when plants bloom or when fish swim upstream to spawn — to answer practical questions: When are the best times to hunt and fish? When should crops be planted and harvested? These days, such homespun investigators have come to be known as citizen scientists.
Increasingly, researchers are tapping into the wealth of observations being made by citizen scientists nationwide, a data trove impossible for scientists to gather on their own (or even with a small army of graduate students). One of the largest repositories of such data is maintained by the USA National Phenology Network, founded in 2007.