Why keep a nature journal?

A nature journal is not a diary of how you felt on a Tuesday. It is a record of what you saw, when you saw it, and what the weather was doing at the time. Naturalists call this phenology: the study of seasonal timing, from the first hazel catkins to the last swift leaving our skies. Keep at it for a year or two and something quietly remarkable happens. You stop relying on generalisations about "spring arriving early" and start making accurate statements about your own patch of Britain.

The real value is cumulative. A single entry about a brimstone butterfly on 14 March is pleasant. Twelve entries across four years tell you that your local brimstone is appearing, on average, a fortnight earlier than it did when you started. That is genuine, useful, local knowledge, and nobody else has it but you.

Getting your kit together

The temptation is to buy too much. Resist it. A journal that lives in your coat pocket will be used; an expensive leather-bound album on the shelf will not.

• A notebook of roughly A6 size with a water-resistant cover, sewn binding and an elastic closure. It should survive a shower and a rucksack.
• A pencil rather than a pen. Ink runs in rain, and pencil works in frost, on damp paper and at awkward angles.
• A hand lens, 10x magnification, for checking leaf hairs, seed heads and lichen. Inexpensive and genuinely transformative.
• A short ruler for measuring leaves, tracks and wingspans, so your records mean something later.
• A phone for photographs, but write your notes at the time. Photographs taken in June are almost impossible to place accurately in December.

What to record, and how

Be disciplined about the basics, because a record without them is close to useless. Every entry should carry the date, the time, the place (a grid reference if you have one, or a clear description), and the weather: temperature, cloud cover, wind direction, whether it rained. Add the day before's weather too if there was a frost or a hard downpour.

Then record what you noticed:

• Birds and animals: species, numbers, behaviour. Three redwings feeding on hawthorn berries. A vixen calling at dusk.
• Plants: bud burst, first flower, full leaf, first ripe fruit, leaf fall. Note the tree or shrub by name if you can.
• Weather and light: the first frost, the first morning with mist on the river, the date the light starts to feel like autumn.
• Sounds and smells: a song thrush singing after dark, the sweetness of gorse, the leaf mould smell of beech woods in November.
• Sketches: a rough outline of a leaf or a bird's silhouette. Drawing forces you to look properly, which is the whole point.

A year of firsts

The easiest way to build a journal is to hunt for "firsts" and "lasts". These are the markers that turn a walk into a survey.

• January: hazel catkins opening, the first snowdrops in a sheltered churchyard.
• February: song thrush and great tit in full voice, frogspawn in pond shallows.
• March: first chiffchaff, first brimstone, hawthorn leaf burst.
• April: swallows back, bluebells and ramsons carpeting the woods, first orange-tip.
• May: swifts screaming overhead, hawthorn in full may blossom, elderflower opening.
• June: meadows at their peak, foxgloves on clearings, first fledglings.
• July: purple loosestrife on wet ground, first ripe blackberries in warm hedgerows.
• August: heather on the heath, sloes swelling, red admirals on buddleia.
• September: fieldfares and redwings arriving, beech mast and acorns falling.
• October: leaf colour at its best, first proper frost, woodcock returning.
• November: leaf fall complete, holly berries reddening, first hard frost.
• December: winter thrushes on berries, owls calling early, the shortest days.

Turning notes into a personal calendar

Once a month, sit down with your notebook and a cup of tea, and write a short summary. Pick the three most significant things that happened and note the dates. Then, at the end of the year, transfer them onto a single page: a simple table or a wheel of the year with one or two anchor events per month.

This is where the journal earns its keep. Compare years. Did the oak come into leaf before the ash? Did the blackberries ripen before or after the first frost? Are the swifts leaving earlier? Keep your route the same where you can, walk it weekly if possible, and be honest about gaps. A journal with missing weeks is still a good journal. Five minutes on a regular walk beats an ambitious expedition once a season.

Foraging notes and a few rules worth knowing

Many people who keep nature journals end up foraging, and the two habits feed each other beautifully. Record what you picked, where, how much, and what you made with it: elderflower cordial on 8 June, a punnet of blackberries on 24 August, sweet chestnuts after the first gale in October.

Do keep to the rules. Under the Countryside Code you may pick fruit, foliage, fungi and flowers for personal use, but you must not uproot any wild plant without the landowner's permission, and you must never pick from protected sites or take more than a small amount from any one spot. Leave the rarities alone entirely, take only from abundance, and never eat a fungus you cannot identify with absolute certainty.

Start this week with a single page. Date it, note the weather, and write down one thing you noticed. That is a nature journal, and it will keep you company for years.