A penchant for small things

Probably most readers of this blog will have a sneaking suspicion I’m over-fond of small things.

So this will do nothing to reassure you because here’s another small thing – but a small thing that’s going to turn into a bigger thing, and a rather interesting small thing which tells us something about ponds generally.

The creature below is a young water cricket which I found on the pond at the weekend: almost certainly it’s the Common Water Cricket (Velia capria), though at this size you can’t be completely certain (the alternative is the northern and western animal Velia sauli which has never been seen in this part of the country).

And the interesting thing is: this is one of those creatures which is commonest on rivers and streams, but also occurs in the apparently completely different environment provided by ponds. Water Crickets patter about on the water surface, trotting busily around in little swarms, like less accomplished versions of their fellow surface dwellers, the pond skaters.

What’s also interesting is that it must have hatched out on the pond – the larvae can’t fly –  from the eggs laid by the occasional visiting adult. They have not regularly been present on the pond – the last I saw were in the middle of winter (which seems to mean they must fly about in winter – which I can’t quite believe: maybe there is some other explanation) and the nearest place the adults could have come from is a stream about 200 yards away.

You can see the adult here at the Biopix site.

Tiny Marsh Dock is growing

Marsh Dock (Rumex palustris) seedling

The tiny Marsh Dock has survived the battering of the heavy rain and now has two roots (or perhaps I should call them rootlets).

Will it survive? It looks so vulnerable.

Equal second commonest damselfly

Blue-tailed Damselfly - found in a quarter of the Abingdon ponds

Diana sent me this picture – which gives me a chance just to say that the Blue-tailed Damselfly (Ischnura elegans: eesh-nur-a el-ee-gans) is found throughout the country, from the Isles of Scilly to the Orkney Isles but, according to the NBN map, not the Shetland Isles – which seems odd. Does anyone out there know if that’s really the case?

In the Abingdon survey the Blue-tailed Damselfly was found in a quarter of the ponds – I should say, only a quarter of the ponds, so you’re doing quite well if you have this animal in  your pond. It was the equal second most widespread damsel after the Large Red (the Azure Damselfly was also found in about a quarter of the ponds).

Diana also made a still from a video of a Blue-tailed female laying eggs amongst Rigid Hornwort.

Blue-tailed Damselfy laying eggs - and yes, both Diana and I know this photo isn't going to win Wildlife Photographer of the Year, but I am the patron saint of slightly blurry photos that show something interesting!

A very special plant comes to our pond (with luck)

Marsh Dock (Rumex palustris) seedling

The seedling above is a Marsh Dock – a pretty unusual plant of the muddy drawdown zones of pond and lakes – that special part of the pond that only appears as water levels drop in the warmer parts of the year.

The seed that this tiny plant germinated from was collected a few years ago – rather by accident- at Pinkhill Meadow, where the plant colonised naturally. At the time this was the only known site in Oxfordshire. According to my Oxfordshire flora it had only once previously been seen in the county, in the 1880s on Otmoor, where it was recorded by the famous botanist George Druce.

Penny Williams picked a small part of one flower spike in order to get her identification of the plant checked by the national recorder (the seeds are distinctive) – because it was a rather unusual plant for the county.

The map below from the National Biodiversity Network shows it is  pretty much on the edge of its range in Oxfordshire.

The national distribution of Marsh Dock (Rumex palustris) in the UK as sown by the National Biodiversity Network

Within a couple of years the plant had disappeared at Pinkhill – perhaps it had returned to the seedbank waiting for conditions to become favourable again.

But we had flower head and we kept the seeds for a few years – waiting for the time when we might grow the plant again, with the aim of taking seeds or plants back to Pinkhill.

So now we’re going to see if we can grow some.

If we’re lucky this is what we’ll end up with.

A rather wonderful dock – I know most people (especially animal lovers like me) will have a tendency to regard all docks as weeds – but docks are really very handsome once you get to appreciate their beauty. Landscape designers call them architectural. For the more practically minded amongst you, the seeds will be eaten by waterfowl.

Marsh Dock (Rumex palustris)

Our inelegant method of growing the plant is to put the seeds on a wet tissue at the edge of the pond and leave them to take pot luck. Probably not what they’d do at Kew, but we’ll see if it works. We’ve got one tiny seedling in a pot in the garden too – probably again it’s not quite getting the Kew level of treatment but – well, we can’t do everything.

If we’re successful this will be by far the most specialised and exacting plant or animal so far found in our garden (there’s a hostage to fortune!).

Solar panels could be a threat to aquatic insects, new research shows

There are many threats to aquatic insects from old technologies like farming, roads, buildings and sewage works as we described here earlier in the year.

But here’s one associated with a new technology - solar panels – which can look not just like water, but a kind of super water.

Aquatic insects are attracted to shiny surfaces because of the way they reflect and polarise light. Solar panels can do this even better than water – so are a kind of ‘ecological trap’ – the poor creatures think they are finding a wonderful pond or lake, and end up fried on a glass and metal plate.

Entomologists have even tried this as a sampling technique because you can get the same effect by laying out shiny black plastic on the ground: in areas with lots of  ponds or streams or lakes you can get a rain of insects, especially water beetles, falling on your plastic. Sadly the technique is quite destructive because, in the sun, the plastic rapidly becomes frazzlingly hot – think ant and magnifying glass.  Insects hitting the sheet are dead within seconds.

It’s tempting to think that, since most solar panels are likely to be in very hot (and usually dry) places this won’t be too much of a problem.

The opposite may be the case: in hot landscapes ponds, pools and streams are not only present but they are often  even more vulnerable to impacts than in wet countries: there are not so many of them, they are further apart, and they also suffer disproportionately from ‘old’ technologies already (like being pumped dry to water strawberries or feed tourist showers).

So it’s quite possible that trapping the animals from these already thin-on-the-ground, and under pressure, ecosystems might be even worse than expected.

Small Pondweed (that’s it’s name – not just a description of its stature!)

Small Pondweed (Potamogeton berchtoldii) seems to be growing well in the New Pond. This native plant - which occurs the length and breadth of Britain, should be within everyone's reach to grow in a clean garden pond

Most garden ponds have a pretty poor and unnatural selection of submerged plants.

This is down to a combination of factors:

- Native water plants can be quite difficult to get started;  clean, unpolluted, water is more or less a pre-requisite, and even then they don’t always take.

- Garden centres don’t supply any native submerged water plants except (if you’re lucky) Rigid Hornwort and Spiked Water-milfoil. Worse, many still provide what they call Elodea crispa – more correctly known as the non-native Curly Waterweed (Lagarosiphon major) – which originates from Southern Africa. This plant has escaped into the countryside where it is probably competing with native plants and, at least in some places, adding yet another threat to our native freshwater wildlife.

- The best source of native submerged water plants – the wild – is often apparently ‘out of bounds’ with many organisations repeating the misleading idea that it is generally illegal to collect any wild plants (it isn’t – except for some specially protected species it is legal, with landowners permission, outside of protected areas). It is understandable why conservation organisations have opted to promote this simple message – (see here for example) – but this message certainly hasn’t helped reduce the spread of non-native plants in freshwater. It is worth remembering that 6 out of 10 garden ponds have non-native species whereas only 1 in 10 in the countryside do, so the safest place to get native submerged plants is the ‘wild’ rather than other garden ponds.

All in all, in my experience, most garden ponds are a bit of a disaster area for plants. But it doesn’t need to be like this.

So in my New Pond – to which we are adding plants – we’re pleased to see the signs of native aquatics getting going. Stoneworts from the local gravel pits are beginning to take; the plant above – Small Pondweed (Potamogeton berchtoldii) – looks to be growing well, we have some little bits of Water-violet (from another local source – a pond we created to strengthen the population of this and other  uncommon water plants in another part of Oxfordshire) and we are hopeful that Blunt-leaved Pondweed (Potamogeton obtusifolius, from Pinkhill Meadow near Farmoor) and Least Pondweed (Potmogeton pusillus) from a village pond in Appleton about 5 miles away will also take.

Already with three aquatic plants growing successfully, and perhaps as many as five in due course, this pond has more submerged plant species than the average countryside pond – shockingly this is just 1 species of submerged plant (read the report here) – and about the same number as the average for top quality unpolluted sites.

The question now is whether garden ponds could actually help spread our threatened native water plants or are merely places where plants collected in the wild come to die.

Sitting Blackbird

Click to enlarge

Oh dear – I’m nervous with this little blackbird sitting out in the open at the edge of the pond.

So many cats around…….wake up and pay attention you silly bird.

Rabbits and tadpoles

I don’t think I answered Jo’s query – when to stop feeding rabbit pellets.

The short answer – I don’t know!

The longer answer: try them with a bit of cat food and see if they like it. If so, maybe stop feeding the bunny brunch.

Mine were pretty keen on cat food back during the election Tad Poll when I maintained voter enthusiasm with the occasional feed.

Oh no they don’t….

Large Red Damselflies laying eggs in the semi-submerged leaves of Fool's Watercress in my New Pond

I read, in a very current (April 2010) article, that the eggs of the Large Red Damselfly are ‘….normally laid in the petioles (leaf stalks) of Broad-leaved Pondweed (Potamogeton natans).’

I did a bit of a double take when I read this because I knew for a fact that it wasn’t true.

In our Old Pond there is no Broad-leaved Pondweed but there are plenty of Large Red Damselflies.  I’ve mostly seen them lay their eggs in dead, floating, leaves that have fallen in the water from the overhanging bushes, and into the stems of the reedmace, just below the water line – and they’ve probably used other spots, too, when I haven’t been looking.

In our New Pond (which also has no Broad-leaved Pondweed) the Fool’s Watercress (above) is a nice place for egg-laying – in the leaves just below the water line.

In the Abingdon garden ponds – none of which have Broad-leaved Pondweed – nearly half the ponds have Large Red Damseflies. So none of these damselflies used Broad-leaved Pondweed to lay their eggs in either.

And looking on a slightly larger scale – the whole of the UK – we found Large Red Damselflies in about 2/3rd of all the ponds we surveyed in the National Pond Survey. But we only found Broad-leaved Pondweed in  one-third of the ponds. So at the very best, half the places where the damselflies were found didn’t have the pondweed.

It looks like it would be more accurate to say that normally the eggs of Large Red Damselflies are not laid in the leaf stalks of Broad-leaved Pondweed – or indeed any other part of Broad-leaved Pondweed – though being a plant of admirable parentage it’s certainly one of the species they will use if it’s available.

Actually, my impression is that Large Red’s seem to be rather catholic in the choice of places to lay their eggs – practically any plant material, dead or alive, at or close to the water surface, floating or attached, seems to do.

Just goes to show – it’s not just the papers that you shouldn’t believe. Sometimes things called ‘The Journal of………..’ can be suspect too.