Phenology refers to recurring plant and animal life cycle stages, such as leafing and flowering, maturation of agricultural plants, emergence of insects, and migration of birds. It is also the study of these recurring events, especially their timing and relationships with weather and climate. Phenological phenomena all give a ready measure of the environment as viewed by the associated organism, and are thus ideal indicators of the impact of local and global changes in weather and climate on the earth's biosphere. Assessing our changing world is a complex task that requires close cooperation...