I’m micro-dosing my way through this wintry moment in American history, with the simple act of looking closely for each tiny hint of spring-to-be as my drug of choice. The nature-infused prescription was laid out for me in the new book “Phenology” by Theresa Crimmins, a primer on the why and how of taking sharper notice of what happens when.
“I invite you to weave a practice of observing seasonal cycles of plants and animals into your life to contribute to science as well as soothe your soul,” writes Dr. Crimmins, director of the USA National Phenology Network, a plant ecologist and an associate professor at the University of Arizona, where the network is based.
Her ask: Become an “everyday phenologist.” After a focused look around outside at particular plants, sign in to the network’s community science app, Nature’s Notebook, and answer some questions about what you just saw.
I could easily get hooked on missions like going to check for signs of life in the beds of ferns and bloodroot (Sanguinaria canadensis), or among the branches of the flowering dogwood (Cornus florida) or pussy willow (Salix discolor). Both the soothing part and the idea of making a contribution feel right just now.
Phenology — from the same root as phenomenon — is about the timing of recurring seasonal events in plants and animals, “timing that is a function of environmental conditions,” Dr. Crimmins said in a recent conversation. These events don’t happen on the same date each year; the variables exerting the strongest influence on their timing, especially in plants, are temperature, day length, and moisture.
As gardeners, our biggest question about timing right now is probably pretty straightforward, though:
Is it spring yet?
The calendar insists that the new season arrives in the Northern Hemisphere precisely on March 20. Instead we can piece together a more textured sense of its start from real-time clues: the first shoots poking through the soil surface, perhaps, or leaf buds swelling and gradually opening. Is the shadbush (Amelanchier) — always one of the first bloomers — awake yet, or have the magnolias’ furry bud scales parted to make way for the blooms?
Was it spring when the Eastern chipmunks, absent since late fall, were suddenly scurrying around in numbers the last week of February? Or will it not truly arrive until the first peeper peeps, or I see a mourning cloak butterfly on the wing — a species that overwinters as an adult even here in my Northern zone, hence its early flight?
It feels as if each organism has its own answer — or maybe more accurately, holds a tiny but essential clue to the vast, intricately connected puzzle.
Tuning into phenology is an exercise in attention — specifically in learning to catch the moments of transition in plants and animals, to discern one phenophase from the next, from the first leaf bud starting to burst open to the last leaf to drop in autumn.
But even with plant species I have long grown, do I really know how to read their signals? In December, the network’s website published its 240-page, lavishly illustrated “Phenophase Primer” focused on the life stages of flowering plants, to help observers differentiate each subtle phase in their seasonal cycles, including flower development, from bud break to open flowers and pollen release right through fruiting. Even deciphering what exactly an open flower is can be bewildering.
“In some species, like a tulip, it’s very obvious,” Dr. Crimmins said. “But in a lot of others, like maples, it’s not so clear. You might not even know there are flowers on a maple tree, for example. And so this document is just super detailed.”
Take the red maple (Acer rubrum), a species native to the Eastern and Central United States, which flowers before its leaf buds break. The trees are polygamodioecious, Dr. Crimmins said, meaning that some trees bear only male flowers and therefore produce no seeds, some trees bear only female flowers, and some are monoecious, bearing both. And apparently individuals can change year to year.
“Some of our observers in Maine have reported that individual trees are monoecious one year and entirely female in other years,” she added.
Any day now, I plan to get better acquainted with the one growing here.
Repeat Observations on the Same Plant
With most of the familiar community-science apps, we are simply asked to record a sighting. The network’s process of sharing is a bit more rigorous, because it seeks not just a species’ presence but its phenological status — trying to get at the “when” of each unfolding stage.
Some 2,000 species are in the network’s database as candidates to be formally observed, 80 percent of them plants. What’s sought are repeat observations on the same individual specimens, so a user must name the individuals they intend to observe (“backyard purple lilac,” or “front yard mayapple”), enter them into their account, then answer a series of structured, species-specific questions every time they check on one. How to make observations is one topic that will be covered in a series of virtual events the network is hosting to celebrate National Phenology Week March 17-21.
The network’s phenological records are the modern-day Western science application of a practice of keen observation that Indigenous cultures worldwide have relied on throughout history.
Among farmers and gardeners, inferences about connections made from such observations have likewise been drawn, yielding bits of folk wisdom — Dr. Crimmins calls them adages — like to plant peas when the peepers peep, sow corn when the oak leaves are the size of a squirrel’s ear, or prune roses when the Forsythia blooms.
More than 40 million records have been submitted since 2009 to Nature’s Notebook, data that can be put to many uses. The observations add up to a leading indicator of climate change, and get at the existential question around each plant and animal species: Can it adapt, or will it perish? And will longtime partners in nature adapt in tandem?
“Interactions between species are at risk of disruption when their seasonal events are cued by different environmental drivers,” Dr. Crimmins writes. Many plants respond to warmth, but many insects become active according to day length. These mismatches can be hard on both: no food for the one, and no pollination services for the other.
Though the pollen season has extended by more than 20 days since 1990, that doesn’t translate to more opportunities for pollinators to gather resources and provide pollination services. The data show some intimate synchronicities increasingly at risk of becoming costly mismatches, Dr. Crimmins explains.
The records also provided insights for a 2020 Penn State study into an edge invasive species in the East hold over native plants, for example. The invasives leaf out earlier and may hold their leaves longer, adding as much as 30 days’ active growing time (in the northern end of the study area) to 77 days at the southern extreme.
And then there are happy stories, too, of species “shifting their phenologies in tandem,” Dr. Crimmins writes, recounting observations by the pioneering conservationist Aldo Leopold, author of the 1949 book “A Sand County Almanac.” Between 1935 and 1945, he noted that Eastern phoebes would arrive back in southern Wisconsin about a week after the early-to-arise native Eastern skunk cabbage (Symplocarpus foetidus) started blooming.
The plant’s foul-smelling flowers attracted insects that the returning phoebes happily devoured.
This duet can still be witnessed today, though earlier than in Mr. Leopold’s time.
Watching Spring Roll Up the Country
So when is it spring, anyhow?
The network’s records can help forecast its timing, and a popular website feature displays animated maps showing the gradual arrival rolling up the country, week by week. The maps indicate when different locations have experienced enough warmth to achieve conditions associated with spring’s historical start — both leafing out, and the earliest blooms.
In her Tucson yard, Dr. Crimmins is gathering clues on spring’s progress as she makes her focused passes twice-weekly through the space, adding fresh observations into the app, and deepening her knowledge, too.
“I have a strong biology background and I think I know what’s going on,” she said. “But I have witnessed so much more incredible detail unfolding right in my midst, and learned a much deeper appreciation for these different organisms and what they do.”
Observations that indicate the co-occurrence of animals and what they are doing in relation to plants always feel like a bonus round. A female broad-billed hummingbird chose Dr. Crimmins’s back porch as its nest site three recent years running, darting to sip at the nearby yellow bells (Tecoma stans). Even absent “mama hummingbird” some days, though, the scene is one of bounty.
“Seeing that progression, it’s always surprise and delight, to discover what has happened since the last time I peeked,” she said. “It’s kind of reassuring to see everything goes on, even though we’re not paying attention. And so when we do pay attention, there’s a lot of gifts for us to receive.”