Did any of you see Matt Hamilton's television debut on Springwatch the other day? He lives in a cottage next to the Itchen Navigation which is a ten mile stretch of chalk stream between Winchester and Southampton and, as part of his dissertation, he filmed the wildlife of this river in spring and summer, and in particular the invertebrates. The mayflies he filmed emerging from their nymph stage at the end of May were marvellous. And their scientific name - Ephemeroptera - is so descriptive in that they have an incredibly short adult life. About ten species in this country live in ponds specifically and one of these, the Pond Olive, has eggs which hatch out literally as soon as they touch water. But this species is different from many of the other mayflies in that it can live for two weeks or so rather than a day. And of course when they hatch, the mayfly provides a feast for bird life.
All the more reason for encouraging invertebrates like these to your pond and to build a pond if you are not lucky enough to have one already. It seems that the ideal garden pond to encourage wildlife would be really quite shallow with the deepest point being not a lot more than a foot deep. This is unless you want to keep large-ish fish. We have found to our cost that introducing fish has greatly reduced the numbers of invertebrates as the fish have multiplied and quite naturally they eat smaller creatures and consume frog tadpoles and newt eggs. If you want to try to have both, a lot of dense undergrowth round the pond will protect many species from predation. This is because most pond creatures will frequent the edge of your pond and the shallower areas. What a pond doesn't want is a good deal of nutrients - hence rainwater rather than tap to top it up, or gravel on the base of a small pond rather than something like upturned turves which some people use - too many nutrients. The problem of floating duckweed which de-oxygenates ponds and reduces the viability of both plants and wildlife is caused by this factor. Natural ponds have a combination of marginal plants, floating plants and underwater plants and if you are planting up, try to use plants that are native to your area** and avoid any over invasive non-natives which can colonise too rapidly. You can just prepare your pond and leave to its own devices.
Some creatures will appear in a matter of hours and it would be an interesting experiment to try this and to see just what you do get. Dragonflies are one of the first creatures to arrive at a newly excavated pond. The species will vary as your pond matures. The first to come are the Broad Bodied Chaser and the Common Darter. This is because they prefer bare sediments in a pond. As the pond develops organically, Brown or Southern Hawkers will arrive and they will predate any other pond creatures that have taken up lodgings in your pond. Frogspawn from February, newts laying eggs in early spring, the arrival of water beetles, pond skaters and lesser water boatmen, pond snails starting to breed, hoverflies - all will arrive at your pond if they find it inviting. We have at least forty kinds of water snails in the UK and they seem to colonise by osmosis but actually are probably brought in the form of eggs attached to introduced water plants or by birds. The Great Pond Snail is about 4cm across but there are much smaller ones than this. Snails appreciate ponds which are too nutrient rich so the intentional adding of water snails could perhaps improve conditions in a polluted pond. The damselflies arrive from May onwards - Matt filmed a male Banded Damselfly emerging from its juvenile form on the leaf of a reed at night.
The males of this species are a striking blue but the females are much more glamorous with a metallic green body and wondrous pale iridescent wings. Surely it is worth preparing a pond just to have the chance to see them. Damselflies lay eggs in grasses and leaf matter so too much tidiness will be detrimental to their ability to breed. Water bugs, too, of all different varieties (and there are about seventy) are also early colonisers and the lesser water boatmen are pretty useful in that they have legs adapted like little combs which trawl through the debris on the bottom of the pond. What can you plant to provide cover for wildlife? Grasses which enjoy damp conditions are both decorative and densely clump forming. Glyceria maxima 'Variegata' has pale green and white stripes and like the yellow striped Phragmites complements strong verticals like the iris. If your pond is pretty large, the native yellow flag irises (Iris pseudacorus) look marvellous and are vigorous. Their thick roots will provide a lot of cover for water bugs, or try smaller native Iris versicolor, shorter than the I. pseudacorus but a beautiful lavender blue. A plant that provides good cover for wildlife is frogbit or, to complicate things, Hydrocharis morsus-ranae. It is a surface free floating plant with shiny leaves which I suppose you could describe as kidney-shaped. On a website I discovered someone complaining about the frogbit they had bought for the grand sum of about £1.70 as it had a 'jelly like substance' on it. Instant wildlife, as this would have been the eggs of water snails! Anything that trails on the edge of the pond will provide habitat for some creature or other. Water mint (Mentha aquatica) is a must for boggy areas and pond edges as it is spreading, fragrant and a favourite of, amongst others, the comma butterfly, the red admiral, the small tortoiseshell and the peacock butterfly, and is one of the foodstuffs of the exotically bright green tortoise beetle. These are well disguised against green foliage but when predators, usually ants, spot them, the beetles cling on with their feet for dear life. Who could ever think that a garden or for that matter, a pond, could be boring...
**A tip from pond warden, Dan Mead, is to provide cover or 'corridor' from your pond to perhaps a hedge or to a patch of dense undergrowth. He also provided a list of plants which he would recommend when planting up a pond, of which I am listing a few.