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Tick-Tock, Nature’s Clock Out of Sync?


A woman and child examine a plant to determine its life-cycle stage.

Observing phenology is a fun activity for adults and children alike.

Nature’s Notebook  invites citizens to get outside this spring, and join their neighbors in observing plant and animal life events in your backyard.

Gardeners, farmers, birders, hikers, anglers, joggers or all-around nature enthusiasts are already recording the recurring events they see in the lives of the plants and animals around them,  such as when cherry trees or lilacs blossom, when robins build their nests, when salmon swim upstream to spawn, or when leaves turn color in the fall.

Each entry in Nature’s Notebook represents important scientific information about an actual event in a plant or animal’s life.  And when amassed together, these observations are making it possible for scientists to better understand how species are responding to climate change and to develop more informed tools for responding to climate change.

This spring, we hope citizen-scientists will help us out in one (or several!) of Nature’s Notebook new campaigns: Cloned Lilacs and Dogwoods; Maples, Oaks, and Poplars; PopClock; New England Leaf-Out Project; the Juniper Pollen Project; and the Common Lilacs and Native Flowering Dogwood Project. Visit the campaigns pages to learn about which species are of interest for your area.

But if these campaigns don’t interest you, there are many other types of species Nature’s Notebook welcomes observations for – including plants, birds, mammals, insects, fish, reptiles and amphibians.

Spring Springing Earlier?

Scientists recently used data collected by observers in Nature’s Notebook to determine that the “green-wave” of spring – or the flush of growth on trees and other plants across the nation – has already shifted – and will shift more dramatically in the future – as the climate changes.  The study (published in Geophysical Research Letters) showed how the green-wave, which now takes about 75 days to travel from Miami to Maine, may take as few as 59 days by the end of the century!  Thus, spring will arrive more quickly, and forest areas may become more similar to one another along the Eastern Seaboard.

And, in fact, warm spring temperatures in both 2010 and 2012 in the eastern half of the country resulted in record early activity of plant and animals – 2-3 weeks early in some places and for some species; the data for spring 2013 – which officially starts today – are rolling in, but they suggest early activity among some plants and animals this year as well.

A bee pollinates a bluebell flower

Citizen-scientists monitor the different life events of certain animals and plants, including the bluebell flower pictured here.

Jake Weltzin, an ecologist with USGS and the executive director of the USA National Phenology Network, which manages the Nature’s Notebook observing program, noted that although an earlier spring brings early birds and beautiful flowers and glorious days at the shore, it also brings us earlier-arriving allergies and pests like ticks and mosquitoes. And while a longer growing season can result in increased yields for some crops, it is risky because of the higher likelihood of plant damage due to late frosts or later onset of drought. For example, in spring 2012, fruit and vegetable crops in portions of the Midwest were damaged from a very early spring followed by frosts.

Phenology, the Study of Nature’s Calendar

The study of when recurring seasonal life stages of plants and animals occur is called phenology, and people have tracked phenology for centuries for the most practical of reasons: when to hunt and fish, when to plant and harvest crops, and when to move livestock or animal herds.

Tracking phenology is just as critical today for the same reasons and for new ones too.  Not only are the data in Nature’s Notebook helping researchers understand how plants and animals are responding to climate change, but also how those responses are affecting people and ecological systems. This information is already being used in ways that benefit society, including developing more accurate indicators of spring, forecasting the onset of allergy season or the chances of western wildfires, managing wildlife and invasive plants, and helping in habitat-restoration efforts.

Green buds on a saguaro cactus begin to bloom

Arizona saquaro will be one of the species looked at by USA-NPN volunteers.

Is Climate Change Knocking Nature Out of Sync?

Changes in phenology are among the most sensitive biological indicators of local, regional and global change. Just as in the United States, many springtime events around the world are occurring earlier — and fall events happening later — than in the past. These changes are happening quickly for some species and more slowly, or not at all, for others, altering relationships and processes that may have been essentially stable for thousands of years.

Some wildlife – like caribou and butterflies and hummingbirds – are becoming mismatched from their plant food resources, which are responding differently.  Migrations for some birds are changing too, as they can now overwinter instead of moving south for the winter, or as they fly north, adjusting their pace to keep up with an advancing front of spring flowering.

Phenology, Pollinators, and Food

Working farms and ranches need phenology information too:  pollination by native insects contributes more than $3 billion in agricultural crops each year. Climate-driven changes in the phenology of crops and native insects could change the effectiveness of insect pollination for better or for worse, and certainly complicates management decisions.  However, because little is known about how pollinator phenology is changing, it is difficult to accurately assess how crops will be affected and how farmers might best adapt. By collecting observations of insect phenology and crop phenology together, the USA-NPN is contributing to our understanding of the changes taking place and helping to ensure the viability of crops across the country.

Where You Come In

In three simple steps, you can become a citizen scientist: 1. Join Nature’s Notebook, 2. Choose the location and species you’ll observe, and 3. Start observing!

By joining the program, you ultimately empower your hobby to benefit scientific discovery.

A woman examines a maple leaf in the forest. A car is partially obscured in the background.

USA-National Phenology Network citizen-scientist Lucille Tower records the one millionth observation on maple vine in the large nature database.

What Changes Are Happening Where I Live?

Want to know more about observed changes in plant and animal phenology in your region over the last century? Explore the USA-NPN’s recent series of regional information sheets:

More about the USA-NPN

The USA National Phenology Network is a partnership among governmental and nongovernmental science and resource management agencies and organizations, the academic community and the public.  There are more ways to get involved – partner your organization with the Network, let us know about legacy phenology data sets or even share a dataset you may have already collected, or help us rescue historical bird migration datasets.  For more information visit USA-NPN or contact Jake Weltzin at

Listen to a Spanish-language podcast about USA-NPN.

Observing Sideoats Grama
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A Nature’s Notebook participant observes grama grass in Arizona. Read More

Anna's Hummingbirds
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An Anna’s hummingbird, feeding her young, is one of 900 species tracked via Nature’s Notebook. Read More

Observing Phenology
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Observing phenology is a fun activity for adults and children alike. Read More

LAVO data collection near climate station_300dpi_i…
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National Park Service staff observe manzanita phenology at Lassen Volcanic National Park. Read More

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Students nationwide are tracking seasonal changes in plants and animals. Read More

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Observers have tracked lilac phenology for decades, documenting plant response to climate changes. Read More

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Page Last Modified: February 2, 2011