The power of the count

How well is wildlife doing in your garden? Are its populations going up, or down? Are all your efforts bearing fruit?

Given that I spend so much time promoting all the things that people might like to do to help wildlife in their gardens, it is rather important that I back it up with some hard evidence. I spend hours trying to help wildlife, but does it actually work?

Well, with the turn of the year, that's another year's worth of data I've collected since I moved here in 2015. Over that time, I've counted birds, butterflies, dragonflies & damselflies, bats, grasshoppers, grass snakes and slow worms, recording the maximum of each that I see on a weekly basis.

Let's start with good news - my bats are doing well. In 2015, I dug my pond, and that is where they congregate at dusk, and the graph suggests that more and more are coming to swoop over it. With the aid of a bat detector, I know they are mainly Common Pipistrelle, with a few Soprano Pipistrelle, and the occasional Serotine.

My Grass Snakes are also doing very nicely. Although I haven't actually found a nest, the presence of very young snakes in summer suggests they are breeding somewhere in the garden. They love the pond, and putting out corrugated roofing sheets gives them the perfect place to snooze in safety.

Grasshoppers present more of a mixed picture. Numbers started very low, and if you'd have asked me last year I'd have said that the creation of my mini-meadows was paying off: it was Chirp City out there. However, this year saw a right slump. Was it because the meadows became rather too thick with Yellow Rattle? It might be the magic meadow plant that suppresses the vigour of grass, but in 2020 there was so much of it there was hardly any grass left, and hence very little for grasshoppers to eat!

My butterfly population was already pretty strong in the first year after I moved in, but I have managed to increase it by about a third. However, I seem to have reached a new plateau. What is encouraging, though, is that I have managed to boost the number of species (red line), with 24 species in the garden last year.

But here's a cautionary tale: my dragonflies and damselflies looked like they were going to take over the world once my pond went in. By the fourth year, I had seen a 20-fold increase in numbers, and my species count had gone up from six to 16. But in 2019 and then 2020, the graph shows a pretty disastrous decline. What is going on?

Well, I've got two possible suspects:

(a) In spring 2019, I did an experiment and introduced ten 3-spined Stickleback to the pond to see what effect that would have. Would they feed the Kingfishers and Little Egrets that occasionally visit? They have bred, like Rabbits. Have they been feasting on all my dragon and damsel nymphs?

(b) Or was it this nymph nibbler? Here I caught it red-handed (or is that red-beaked?) with a dragonfly nymph - and I saw it take over 200 in just one visit.

I hope I haven't lulled you to sleep with graphs, and I'm not saying that everyone needs to go out and start number crunching to the extent I do (although I should say it only takes a few minutes each week just to do a bit of recording). But hopefully it shows how a bit of counting can reveal things that we wouldn't otherwise be able to judge by memory and guesswork alone. And it also shows that the things we do in the garden to help wildlife do pay off - most of the time!

Which of course leads me to the fact that it is Big Garden Birdwatch next weekend (29th, 30th and 31st), where together we can count the garden birds of the nation, and in doing so find out how they are faring. If you only do one count of anything a year, that's the one!