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Walking with Wildflowers: citizen science along the Pacific Crest Trail

Walking with Wildflowers logo | Used with permission

by Nic Kooyers

My personal limits are pretty clear – I only have two hands, two feet and can only be in a single location at a given time. Ditto for all the field assistants, graduate students, and other colleagues that I work alongside. Unfortunately this can make collecting the large-scale datasets that we need to address our scientific questions somewhere between difficult and impossible.  Luckily we live in the age of citizen science, where passionate members of the public contribute time and effort to collect and analyze scientific data to assist professional researchers. For example, citizen scientists have made over 370 million bird observations in eBird and 14 million observations for the USA National Phenology Network leading to discoveries of shifting patterns in phenology, or the timing of critical life events, in bird migration and plant reproduction that are associated with recent climate change.

Citizen scientists are extremely important to my research examining the ability of plant species to respond and adapt to climate change. In the last few years, I, along with colleagues Benjamin Blackman and Jack Colicchio at UC-Berkeley and Katharine Gerst and Erin Posthumus at USA National Phenology Network, have developed a citizen science program called Walking with Wildflowers to determine which subalpine and alpine plant species may be most at danger from shifting growing seasons associated with global warming. As average temperatures have steadily increased and more precipitation falls as rain rather than snow, growing seasons in mountainous regions now start noticeably earlier. To cope with these changing conditions, plant species must be able to shift the timing of basic life events including flowering, fruiting, and setting seed to successfully reproduce.

Walking with Wildflowers collage
Walking with Wildflowers identifier and sites | Photo by Nic Kooyers

Walking with Wildflowers helps me determine which species may be vulnerable to shifting climatic conditions by utilizing hikers along one the nation’s longest and most famous trails, the Pacific Crest Trail (PCT), as volunteers to survey plant flowering patterns in remote mountainous regions.  The concept is pretty simple – my colleagues and I have gone out and marked plants at several designated sites along the trail and ask that passing hikers make simple observations such as whether a given plant is flowering and/or how many open flowers are on a plant. The participants record these observations on their smartphones with the Nature’s Notebook mobile app, and the stored data is later transmitted to the USA-National Phenology Network’s database via wireless or cellular networks. This entire process takes a hiker less than 15 minutes per site, but provides us with stream of data that researchers and park personnel could not hope to collect by ourselves.

Walking with Wildflowers Lydell Canyon
Lydell Canyon, an area ripe for Walking with Wildflowers data capture | Photo by Nic Kooyers

Although a single hiker may observe a given plant at a particular site just once, different hikers along the PCT will record observations on the same plants over time, producing a season-long and multi-year data set. This crowd-sourced information resource will be extremely valuable for allowing researchers to answer important questions about how plant species are responding to climate change. For instance, the flowering observations that are generated by hikers participating in Walking with Wildflowers will be used to identify which species are able to shift the timing of flowering to thrive in ever earlier, warmer, and drier growing seasons. Furthermore, by examining year-to-year variation in flowering patterns, researchers will be able to compare different species’ responses and better understand why certain species are able to respond while others are not. 

This is the first year that volunteers can start recording observations and this season’s efforts will focus on 20 plant species along segments of the PCT within Inyo National Forest, Yosemite National Park, and North Cascades National Park. The most challenging part of this work to date has been recruiting hikers and backpackers as volunteers. We have found hikers are far more willing to take observations after having face-to-face interactions with us, and we are currently working to expand our social media presence via Facebook and get the word out to those who frequent the trail.

If you are planning a trip to Inyo, Yosemite, or North Cascades or have friends who may be hiking the PCT this summer or next, definitely get in touch! The PCT crosses diverse environmental conditions that are inhabited by spectacular wildflower, shrub, and tree communities, and being a citizen scientist with Walking with Wildflowers is a fantastic way to enrich your knowledge of these fascinating plants while also advancing much needed conservation research. To get involved, please visit the Walking with Wildflowers website, interact with us on Facebook (Walking with Wildflowers) or email us at


About the author 

Dr. Nic Kooyers is an assistant professor at the University of Louisiana, Lafayette whose research examines how plants adapt to current and future environments in the age of climate change. He is particularly interested in understanding how plants can cope with stressful conditions such as droughts, drastic seasonal variation in climate, and herbivores. Walking with Wildflowers combines two of his passions – the biology of subalpine plants and backpacking.

Did you enjoy today’s blog? Please let Nic know what you thought by reaching out to him at, visiting the Walking with Wildflowers website, or following Walking with Wildflowers on Facebook.