How do you record the first signs of spring, and why bother?

Pick a few species you pass at least twice a week, and write down the date you first see a particular event happen to each of them: first flower, first leaf, first swallow. Do it again next year in the same spot. That is phenology, and the record you build gains value with every year you keep it going. You can send it to the Woodland Trust’s Nature’s Calendar, or just keep it in your notebook.

An unlovely word for a lovely habit

The Woodland Trust defines phenology as the study of seasonal changes in plants and animals from year to year, especially their timing and their relationship with weather and climate. The word itself was coined around 1849 by the botanist Charles Morren. People were at it long before that, and the Trust notes that blossom dates tied to festivals in Japan and China go back to the eighth century.

In Britain the story usually begins with a Norfolk landowner. Robert Marsham started noting spring events on his family estate near Norwich in 1736, and kept it up for 62 years. His ‘Indications of Spring’ grew to 27 events, including first flowers, the leafing of trees, and the arrival or first song of migrant birds. A site devoted to him adds some lovely detail. He listened for cuckoos, watched the breeding of rooks, frogs and toads, and recorded the flowering of turnips, an important crop in Norfolk. His findings were reported to the Royal Society in 1789, the year Gilbert White’s book came out.

What makes this remarkable is what happened after Marsham died in 1797. His family carried on, generation after generation, until 1958.

Then there is Jean Combes, who began recording in 1947 and whose oak budburst dates became famous among people who study such things. The Trust says she kept going for more than 70 years until her death in 2023, aged 96, in what is believed to be the longest such record by a single person anywhere. She was given an OBE for it in 2009, and she handed the job on to a friend. Amateurs have done a great deal of the work in this field.

What you are looking for

Nature’s Calendar works from a fixed list of species and events, chosen by scientists. Even if you never submit a thing, its categories make a good framework for a notebook page. These are the Trust’s examples, and you can rule a table like this into the back of any notebook.

Note how much of that list falls outside spring. The title of this article is the question people ask, but autumn dates count as well, and the Trust’s scheme wants them. So you do not need to wait. As we write in November, tinting and leaf fall are being reported, and one bare tree is a perfectly good first entry.

Doing it properly in five sentences

The Trust’s quick guide is sensible and brief, and this is the heart of it. Choose species and events you can check at least twice a week, though something like a butterfly needs watching only until its first appearance. Choose places you visit anyway, such as the ash tree on your way to work or the pond in the local park. The Trust treats a location as a circle with a 20 metre radius, so be precise about where. Record the first date you see each event. Choose mature trees of roughly 30 years or older, since young ones can behave differently, and record every event on the same tree.

Two habits of our own to add. Write down the days you looked and saw nothing, because ‘not yet on the 12th’ makes ‘first seen on the 15th’ far more trustworthy. And note anything odd about the year, such as a hard frost or a dry spring, as you will not recall it later. Both fit naturally into a regular nature notebook.

What the dates add up to

These long, plain lists turn out to be very useful evidence. According to the Woodland Trust, its Nature’s Calendar database now holds 2.9 million records, used by researchers around the world, and it is believed to be the longest written biological record of its kind in the UK.

The Trust summarises the direction of travel like this: spring events such as budburst and flowering are getting earlier, fruiting is getting earlier, and late autumn events like leaf fall may be delayed. It cites a calculation that spring across Europe is advancing by 2.5 days per decade. The worry is that species respond at different rates and can drift out of step with what they feed on. One observer’s dates in one place prove none of this, of course. It takes a very large number of people looking at very ordinary things, and that is exactly what makes your entry useful.

Marsham could not have foreseen most of that. He wanted to know when things happened. There is something steadying in a practice begun out of curiosity that turned out, nearly three centuries later, to be so badly needed. If that appeals to you as a reader as well as a recorder, begin with our list of nature books, where the same patience shows up in prose.