The Garden Pond Blog

The slightly misnamed Grey Wagtail - it's most striking feature is the blaze of yellow on its bottom and back (I can't claim the pic - this is simply culled from the web)

I mentioned before that Grey Wagtails – a bird that really needs streams and rivers – often fly over the garden, and from time to time make brief stopovers on the roofs around us.

The reason we see them is the stream at the end of the road, about 250 m from the garden.

So I’ve been hoping for some time to twitch one in the garden – and today, I got my wish as one tripped its way around the new pond for a minute or two before chink-chinking its way back to the rooftops (check out the characteristic call here – the sound captured on this Italian website is the closest I could find to the real thing amongst the free sites, although the calls recorded by Andreas Schulze on the 17 CDs of Die Vogelstimmen Europas are better, but more expensive to access).

What’s a bit more interesting about this than just an unusual garden tick is that here we have a way to get seeds, spores, eggs, bits of plant and live animals from the margins of the nearby stream straight to our pond – and back – on the feet of a Grey Wagtail.

So next time I need to get it to wipe its feet on the welcome mat to see what its bringing along.

And then there was one: after rain I have one pond again

A couple of blogs back I wrote about how pleased I was the pond was at last drying down a bit.

And as it went down, and became three ponds rather than one, we saw how the water chemistry of the three basins started to change, with conductivity values of 72 in the big basin (at the back), 94 in the medium basin (right) and an intermediate 84 in the small basin at the front. It’s not a huge difference between the three – but I think this can only but help to contribute to the habitat diversity in the pond.

This was what I hoped would happen when I made the pond – by having three basins there would be more variety in pond habitat, in this case greater variation in water chemistry.

Now after a bit of rain I’ve got one pond again – and the process has been reversed. Conductivity measured in the same places is 71, 68 and 67 – practically the same again in all parts of the pond.

The new pond showing that looks aren't everything - it already has an unusually good crop of animals

We surveyed the new pond last week.

The pond looks pretty awful but we found a surprisingly wide variety of animals: most exiting was a full grown Emperor Dragonfly larva (there are excellent pictures of this species on the Biopix website).

It’s actually one of the easier larvae to recognise – and, with practise, do-able in the hand. The shape of the head is the distinctive feature – it’s more rounded in outline compared to other hawkers.

Actually it’s not such a big surprise to find this dragonfly in the garden: emperors are well known for being able to breed in garden ponds, although we’ve no idea at present what proportion of garden ponds they actually occur in.

There’s no way of knowing whether ours was brought in with the plants we added or was the result of natural colonisation.

This emperor is the fifth species we’ve found breeding in the ponds in the garden: the others are Common Darter, Brown Hawker, Broad-bodied Chaser and Large Red Damselfly.

The three basins have separated out now as water levels have gone down

For the first time in two and a half years the pond is just starting to look the way it was designed to:  as water levels fell during the dry September weather, it separated into three basins of different depths.

So rather than keeping it constantly topped up, a very unnatural state of affairs as water levels naturally go up and down during the year with many advantages for wildlife, I made it with three basins which would separate out into three different ponds as water levels fell.

In this way I hoped to maximise diversity of habitat in the pond – the three ponds will have slightly different water chemistry, different habitats, and should dry out at different times.

The conductivity today was 72 in the big basin (at the back), 94 in the medium basin and an intermediate 84 in the small basin at the front. When the pond is full conductivity does not change by more than 5 or 10 points from one part of the pond to another, so even a short period of separation looks like it may be causing greater than normal variation in water chemistry – it is this kind of variation from one pond to another which helps to make ponds collectively such rich wildlife habitats.