Creating Habitats for Dragonflies.
With so many pressures on wetland habitats from the activities of man, it is beneficial for all forms of wildlife to help create suitable pools for both Dragonfly and Damselflies to breed. This can be the simple garden pond or a complex wetland on a nature reserve. Ponds are also very important as breeding sites for newts, frogs, as well as Dragonflies and Damselflies. If all you do in your life towards practical conservation is to build a pool in your garden then you can pat yourself on your back. It will open up a whole new world for you to enjoy. You will discover that 'Pond Watching' is one of the best forms of relaxation there is. To attract Dragonflies to breed you do not necessarily need a huge pool. Rod Dunn in his groundbreaking 1984 publication, Derbyshire Dragonflies, makes an example of this. In it he tells of a stone tank on Stanton Moor which normally contained six inches of water and also larvae of the Southern Hawker Aeshna cyanea. During the severe winter of 1981/82 the water in the tank was seen to be frozen throughout its depth. The frost continued for many weeks and the site was not visited again until early summer when many larvae could be seen to be alive in the water. So if you haven't room in your garden for a pool, a trough, a half barrel or old sink will still provide an attraction for a multitude of aquatic life.
What do Dragonflies need?
All Derbyshire Dragonflies need permanent water with a stable surrounding environment with a suitable area not far from the water for adults to feed and use as roosting sites. You will need to pick a sunny and sheltered spot especially from north and easterly winds. The pond will need an abundance of marginal, emergent and submerged aquatic vegetation for both adults and larvae. Adults need plants to perch on, roosting and for laying eggs into (oviposition). Submerged and emergent plants provide places for developing larvae. Emergent plants are essential for larvae to climb up when ready to merge as adults. Newly emerged and immature adults require sheltered vegetation a few metres from the water.
So you want to build a Pond?
So you would like to build a pond in the back garden? Make sure you are going to build it in a suitable place and not destroy some existing wildlife habitat in the first place. The choice of site and the depth and outline of the pond are fundamental to success or failure. If you can and you do have the space, the bigger the pond the better especially if you wish to attract 'loads of Dragonflies'. Most British species can breed in ponds about 14 square metres if the habitat is suitable. The design should include the provision of shelter from prevailing winds. The pond should be sited away from overhanging trees for, not only may they shade out any proposed aquatic/marginal vegetation, but an excessive amount of autumn leaves pollute the water and can be a nuisance to clear out. Few Dragonflies like shade! Also avoid other possible sources of pollution (e.g. run off from nearby roads or from intensively farmed land). Establish the correct depth. Whilst shallow areas are important, a uniformly shallow pond will heat up in summer, reducing the oxygen level of the water and perhaps even dry out. It is important to have a sufficient depth of water (e.g. 0.75 to 1 metre) at the deepest point. The shape of your pond will depend upon individual circumstances but an irregular outline looks more natural and provides a longer edge. Vertical sides and sharp corners should if possible be avoided; shallow margins sloping gently down from the water's edge are important for the growth of floating and emergent plants and hence the larval habitat for the dragonflies you wish to encourage. Areas of shallow water should be considered for the southern and western aspects of the pond. The gently shelving sides have three functions: a) A large area of shallow and marshy water is created to allow important marginal and marshland flowers to be planted. B) Animals can easily crawl in and out of the water .c) If the pond freezes the expanding ice will slide up the sides and not force the sides apart.
Before marking out the proposed site check whether there are any underground services such as gas, power and water pipelines or telephone cables. Now is the time to consider the size of the pond. If you are lucky enough to have a huge garden then a large pond it is. So perhaps it may be worth hiring in a self-drive mini digger or find a skilled friend quick! An even better way is to invite all you friends to a 'build a pond party' for a fun weekend, just tell them to bring a spade! Whatever size pond you decide upon, it will not be a five minute job! Strip the topsoil off and stack separately for use in the pond. Do not spread it over topsoil- always keep them separate. Use the subsoil to create a bank somewhere else in the garden or even build a hibernaculum for overwintering amphibians. The soil can be mixed with rubble and then dig a trench about half a metre deep. Then fill in with your rubble and soil with the odd drainpipe in. Create cavities and then fill it over perhaps 0.5metres above the ground with access into the bank for amphibians to crawl into. You can make it as large or small as you wish. One built at Pleasley Colliery by the Dragonfly Pools is 20 metres plus long and three metres high. Dragonflies love warming themselves up on it as the bank faces south. Definitely a penthouse hibernaculum, but hey we are building ponds here!
Peg out the pond or use a hosepipe into the shape you want. It is a good idea to leave it a few days for you to sort out what you want. If you are using a butyl-rubber liner, can you afford it at the amount required? There are various liners available for garden pond creation.
Concrete and fibreglass
Not as a popular a method as it used to be. Concrete ponds are difficult to do. They often look unnatural and are susceptible to cracking from frost action. Fibreglass pond liners also look unnatural and tend to have steep sides, which become death traps for Hedgehogs. Best leave them for the Koi Carp fanciers!
This is the good old fashioned method of lining a pond. Puddled clay not only forms an excellent base for building a natural pond it is superb for establishing plants into. The important bit whilst building it is not to allow it to dry out and crack the 'puddle' or clay liner. If you live on a clay sub soil then you are off to a good start and it is less likely to develop permanent leaks if it dries. Clay for puddling can be brought but bringing in to site can be expensive. A powdered form of clay called Bentonite is available useful for large schemes but again it is expensive to use. It swells on contact with water forming an impervious lining. It is best left to the professionals! If you wish to use clay then you should lay the clay like paving. Making sure that the lumps are abutting tightly to form an even layer on the entire area of the pond. Water the clay well and 'puddle' or trample it to form a continuous sticky layer. Another excellent party activity to achieve a good impervious liner. Then put a layer of soil over this in which to establish plants.
Flexible pond liners
Today these are the commonest forms of garden pond liners. As long as you are careful about the edge of the pond and make sure the surplus liner is hidden a natural looking pond is easy to build. Flexible liners such as butyl, PVC or polythene sheeting are used. If you are looking at a long term life for your pond then use Butyl rubber. Polythene and PVC deteriorate especially when exposed to sunlight. Butyl may cost more but it is worth every penny. If the proposed pond is large or an irregular shape it may be difficult to estimate how much liner to buy. It can be bought in particular sheet size so you could build your pond to fit. You can order from the manufacturers. They may custom build your liner if you supply them with a scale plan of you design. Always allow surplus for the edging to allow for the water to drag down the liner as it fills up. As most garden pond creators will use Butyl-rubber liners here is how to do it as described in Fran Hill's excellent Derbyshire Wildlife Trust hand book, Wildlife Gardening.
- Prepare the site. Dig hole approximately 200 mms deeper than depth you require to allow for sand, matting and soil to go under the liner. Retain top soil.
- Trim excavation to a plane surface removing large stones, backfilling and tamping holes and sharp hollows.
- Firmly compact the base and sides. All banks to slope gently-no steeper than 3:1 ( or soil will slip). To take up slack in the liner produced by sloping pond margins dig a trench at each corner of the pond running from the bottom to above the water line. Cut the trench with sloping sides and rounded bottom and corners. Increase the depth uniformly from zero at the bottom to sufficient at the top to take the surplus liner.
- Dig a trench one spit wide and one spit deep along the bank just above the intended top water level. Lay the edge of the sheeting in this so that it can be held securely by back filled earth. (This prevents it pulling loose under the water's pressure.)
- Spread 50 mm of sand over the surface of the excavation and overlay polypropylene matting to protect the sheeting from puncture. If matting is too costly use thick sheets of newspaper or carpet.
- Lay pond liner. Handle sheeting with care-walk on it only with soft rubber soled shoes. Do not pull sheeting taught. Do not crease.
- Spread a further protective layer of matting, old newspaper or carpet. Once liner is completely covered spread a layer of soil at least 125-150mm thick over the protective layer.
- Bank excess excavated soil around edge of sheeting for extra protection. Light must not be allowed to reach the liner or it will deteriorate.
- Where grass adjoins the pool margin lay turves up to the water's edge.
- Fill pond. Rest hosepipe on top of a square of polythene or matting on pond bottom and let the water trickle onto it to prevent the soil being washed away, exposing the butyl liner. Derbyshire-Dragonflies add the following:-
- Let the pond stand for a week at least before you introduce any plant life so as to allow the release of chlorine added during water treatment. Unless you have collected rain water especially for your new pond.
- If you want the Dragonfly to be King of your new garden wildlife pool. DO NOT be tempted to introduce any Fish. Fish will eat everything of interest especially Dragonfly Larvae! So you have a hole in the ground filled with water. What do you do next?
Stocking a pond
You could just wait and see what nature decided to do with your pond but unless you live close to other ponds and water bodies you could have along wait. It is a good idea to collect a few bucketfuls of sludge and water from a well established pond. By doing this you can introduce hundreds of pond creatures into your new pond. Always make sure that you have the landowners permission to do this. Also check that there are no invasive alien plants in the donor pool. See the section of invasive Plants on the web site for further details. Introducing indigenous plants will be another source of animals. In spring you will find other pond owners have a surplus of plants but avoid bringing in Frog and Toad spawn. You may unwittingly transfer harmful diseases such as red leg disease a killer of frogs. If your pond is right amphibians will find it themselves. To be a success your pond needs to planted correctly especially for Dragonflies. Here is a helpful list for the garden pond Dragonfly Hotel.
Deepwater -submerged plants
Curly pondweed - Potomogeton crispus
Water Starwort - Callitriche spp
Hornwort - Ceratophyllum demersum
Spiked Water Milfoil - Myrophyllum spicatum
Deeper water Floating Plants
Stiff-leaved Water Crowfoot - Rannunculus circinatus
Frogbit - Hydrocharis morus-ranae
Broad-leaved pondweed - Potomegetum natans
Amphibious Bistort - Polygonum amphibium
Yellow Waterlily - Nurphar lutea
Fringed Waterlily - Nymphoides pelatata
Shallow water emergent plants
Flowering Rush - Butomus umbellatus
Water Horsetail - Equisetum fluviatile
Bur-reed - Sparganium erectum
Water Plantain - Alisma plantago-aquatica
Common Spike Rush - Eleocharis palustris
Bog Bean - Menyanthes trifoliata
Reed Mace Typha latifolia & Common Reed Phragmites australis they will more than likely find the pond themselves and are very rampant. Confine to a planting basket if you do want them and keep a close eye on them!
New Zealand Water Stonecrop Crassula helmsii a complete horror of an invasive alien plant. Do not let loose in Derbyshire!
What else can you do for Dragonflies?
- If you can leave an area of long grass (a mini meadow) by the pond for Dragonflies to shelter or roost up in. It will also provide an area for insects to use and in turn be fed on by the Dragonflies/Damselflies
- Provide perching sticks along the edge of the pond
- Put an old log or two in at the water's edge to gently rot down and provide an egg laying spot for Brown Hawkers Aeshna grandis.
- Put down some slate at the water's edge or piles of flat stone and see if you attract Black- tailed Skimmer Orthetrum cancellatum. They love to sun themselves in open areas. Colonisation
The rate at which a new pond becomes colonised by dragonflies depends mainly on the distance between the pond and other water bodies supporting dragonfly populations. Most dragonflies are efficient dispersers and they find new habitats very quickly. Experience shows that new ponds rapidly become colonised if there are dragonflies breeding within two or three miles of them. New ponds take some time to mature and, although they may be visited by many species quite soon after construction it may take a few years before the visitors actually breed successfully in them. Whilst ponds were being built at Plealsey, Common Darters Sympetrum striolatum were seen to egg lay in the water right next to the Hymac 360 earth mover as it worked.
In Derbyshire the following species are known to frequently colonise garden ponds:-
Azure Damselfly Coenagrion puella
Blue-tailed Damselfly Ischnura elegans
Southern Hawker Aeshna cyanea
Broad-bodied Chaser Libellula depressa
Common Darter Sympetrum striolatum
Why not let Derbyshire-Dragonflies know what your Garden Pond attracts? Just send an email with your list and we will compile a listing of Derbyshire Garden Hotspots. We would also be interested to hear from Garden Ponds around the world to see what Dragonflies visit your back yard pool.
Where you can it is sound conservation practice to renovate old ponds rather than create new ones. Plant and animal communities, which have already become established can, through careful management, be modified and enhanced. Always think about what you are doing and how any work on a pond you propose will effect the wildlife already there. Populations of dragonflies should be monitored before and after management takes place in order to test its effectiveness. Heavily silted and overgrown ponds should never be cleared completely in one operation. Autumn and winter are the bets times and, if clearance is staged over a couple of years or more, natural colonisation can take place. Unwanted plant growth should be removed with restraint. The use of herbicides is not recommended (you wouldn't even think about it would you?). This is because the decomposing plants reduce the oxygen in the water and may be detrimental to dragonflies and the other animals on which they depend for food. Silt and leaf litter should be controlled with care since they provide important habitat for bottom dwelling larvae the rule is not to be over zealous. Remove a little at a time! Heavily shaded ponds should be opened up to expose them to sunlight, either by selective removal of shrubs and trees or by careful pruning. Coppicing or pollarding may also be considered.
If the pond is to be used by other always think safety. Consideration should be given to removing or shielding potential hazards such as deep water, steep banks etc. If you are thinking big on wetland creation then the following texts are well worth a read. Andrews, J Gravel pit restoration for wildlife. RSPB Sandy Beds Oliver L. Gilbert & Penny Anderson 1998 . Habitat Creation and Repair. Oxford University Press ISBN 0 19 854966 (Pbk) Sutherland W.J and Hill, D.A, (ed) 1995 Managing Habitats for Conservation. Cambridge University Press.