120 Years of Decay

I put it to you that we have just experienced a dire spring, migration-wise. This highly subjective analysis is supported by no data whatsoever, and of course open to rebuttal by any who feel differently. And if their case is supported by numbers...well, I am sunk.

We do like numbers. Especially we like to convert them into trend graphs, with time along the x-axis. I have been looking at quite a few of those lately. Now that I am a pensioner it is my right and privilege to moan about how awful things are, compared to 'back in the day', but I did at least feel I should back up such old-fartery with data. Well, what can I say? A bit of research recently into various branches of our UK natural history revealed such a depressing state of affairs that I could not bring myself to write the blog post I had planned. It was just one decline after another. Apart from Red Kites and various egrets, downward trends everywhere I looked. I mentioned it briefly on social media last week, and one reply included this comment:

...but I do know some naturalists who still insist that all is not as bad as we think...

Which got me wondering how anyone might have such a view, and if they could support it with numbers.

The trouble is, I have 50-odd years of active birding memory. In the early 1970s I learned Yellowhammer song from the pairs that still bred just a mile or so from Wembley Stadium. Even in the 1980s it was easy to see a number of breeding species within the London Recording Area that are now long gone. And springtime visits to the coast always seemed busy with migrants back then...

Or is that just rose-tinted nonsense?

Some of my contemporaries - many of whom were far more active than I ever was - still have their field notebooks from those times. I wonder what sort of numbers they contain, and what those might reveal.

Still, 50-odd years is not really that much, is it? What about 120 years? By chance I was browsing Seventy Years of Birdwatching by H G Alexander, and came across a breeding bird survey he carried out with his brother in the early 1900s. There are numbers. Lots of them. And I thought it might make interesting reading for birdwatchers of 2025, especially those who have had their baselines shifted even further than mine.

H G Alexander refers to a short paper that he and his brother had published in the March 1909 edition of British Birds, and I have nicked some of it for this post. It is entitled On a Plan of Mapping Migratory Birds in Their Nesting Areas, focuses only on migrant breeders like Willow Warbler, Whitethroat and so on, and is based on surveys carried out in Kent and Sussex. The paper includes a map of part of their survey area in Tunbridge Wells, and I was surprised to discover that much of the green space back then is still green space now. So, here are the Alexander brothers' survey results for a specific selection of the species covered, superimposed upon a modern-day OS map...

The original BB map is depicted by the light blue rectangle. It covers an area of less than a square mile, more like 1.5 square kilometres.

No doubt you noticed the two pairs of Red-backed Shrikes and Wrynecks, and three pairs of Wood Warblers. And what about those nine pairs of Spotted Flycatchers? I didn't even bother trying to squeeze in the 19 pairs of Willow Warblers. I wonder how many of those species still reside in that area.

Personally I find this pretty amazing stuff, but the BB paper includes survey results from a much larger area around Tunbridge Wells - eight square miles - as well as four square miles around Wye in Kent, NE of Ashford. Here they are, along with the original survey map referred to above...

Screenshots of BB paper from March 1909 edition. Obviously Willow-Wren = Willow Warbler and Wood-Wren = Wood Warbler. And note archaic spelling of 'showing' in map caption!

Frankly, those numbers blow my mind. Extrapolate this across the UK, and, well...

I wonder if some might be tempted to point out that this is all a bit irrelevant, because the world is very different now. And of course they are correct, the world is very different now. There are a lot fewer birds in it! Which in my view makes this almost 120 year-old data immensely relevant. Most of the trends available to us right now cover five decades or less - a lot less in some cases. Imagine if we were to push the x-axis all the way back to 1908 and were able to fill in all the numbers in between. I suspect many graphs would look like the side of a mountain, with our present-day trends no more than its foothills.

And while I'm being so negative, how about this...

Of course, such a short-term trend is not to be trusted, and most probably the 'some naturalists' mentioned earlier in the social media quote are correct: things are indeed nothing like as bad as we might think.

Yeah, right.

Any accusations of doom-mongering on my part are fully justified I fear.