USA NPN National Phenology Network

Taking the Pulse of Our Planet

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Phenology is vital to many aspects of ecology and society and you can help advance our knowledge!

Image credit:
Richard House

Why Phenology?

Phenology is nature’s calendar—when cherry trees bloom, when a robin builds its nest and when leaves turn color in the fall. 

Phenology is a key component of life on earth.  Many birds time their nesting so that eggs hatch when insects are available to feed nestlings.  In turn, insect emergence is often synchronized with leafing out in their host plants. For many people, allergy season starts when particular flowers bloom—earlier flowering means earlier allergies.  Farmers and gardeners need to know when to plant to avoid frosts, and they need to know the schedule of plant and insect development to decide when to apply fertilizers and pesticides. Many interactions in nature depend on timing.  In fact, phenology affects nearly all aspects of the environment, including the abundance, distribution, and diversity of organisms, ecosystem services, food webs, and the global cycles of water and carbon.


Changes in phenological events like flowering and bird migrations are among the most sensitive biological responses to climate change. Across the world, many spring events are occurring earlier—and fall events are happening later—than they did in the past. However, not all species and regions are changing at the same rate, leading to mismatches. How plants and animals respond to climate can help us predict whether their populations will grow or shrink – making phenology a “leading indicator” of climate change impacts. 


Phenology plays an important role in human culture, as well. Festivals around the world celebrate annual phenological events from whale migrations to cherry blossoms. 


We know a lot about phenology, but there is still much to learn. You can help advance the field by:

  • Collecting data for Nature’s Notebook in your yard, a nearby park or as part of a field study.
  • Organizing a phenology effort locally for data collection, research and/or education.
  • Participating in one of our Research Communities or attending a phenology-related meeting.

We invite you to join us!