Phenology

This year I saw my first Swallows on 19th April, last year I had to wait until 30th. Taken on their own, these two dates of observations by a single person won’t mean much but, added to others over many years and collected by many people, this sort of data can be gathered to understand the phenology of a species.

The term phenology refers to the study of the seasonal or cyclical behaviour, usually of animal or plant life, in relation to the climate and habitat factors. These days, with our growing awareness of climate change, the focus on this has increased.

Examples can include the first appearance of migratory birds such as the Swallows I mentioned earlier, or Swifts which will be arriving this month; first emergence of leaves or flowers of particular species; first flight of butterflies; dates of autumn colour appearing or birds laying eggs each year.

I keep a different kind of diary to most people. It logs some of these events, and rather than being specific to the year, it rolls on endlessly for me to add to each year. I’ve only been doing this since 2022, but I picked up the habit from my mother who began hers in 1984.

As well as things like the first Bluebells and Cuckoos in spring, we note incredible weather events. She recorded snow on the 6th of May 1997 and I noted seeing the Northern Lights with my bare eyes last October from my Cambridgeshire garden.

In the 41 years she has been keeping hers, my mother has recorded the arrival of Redstart and Spotted Flycatcher in our garden on the Welsh borders; hearing the Curlew in the fields round the house each spring; the date the first wild Daffodils burst their buds; details of bird nests found in the garden & successful broods fledged; the departure of the Swallows and House Martins, as well as extreme weather events like the snow I mentioned, storms, floods, droughts and heatwaves.

Put together, this gives a much broader picture of the area in which I grew up and the changes that have occurred there during this time. I can pinpoint with a certain degree of accuracy the year that the last Curlews bred in the neighbour’s field (2006). I can tell you that her earliest record for seeing Swallows was the 3rd of March 1997 but that three years later in 2000 it was snowing on the same day.

We both admit that we find it easier to document the spring arrivals than the autumn departures, and that we sometimes forget to note the arrivals in the autumn too – the Fieldfares, Redwings and Waxwings that grace our shores, or the Geese that flock in their thousands to British coasts for the winter. I’m hoping that I might be better this year at documenting a few more things. Sharing and reminiscing over some of the observations in my mother’s journal has been fascinating on so many levels and has inspired me to look more closely and with more wonder at the world around us, and aim to compile a similar record.

If you’d like to do something similar you could use a standard diary – the more space the better – or a dedicated book like “The Biotime Log” by Maddy Harland which is designed for this purpose.