Spawn & tadpoles: in my garden
I think there is too much spawn/too many tadpoles in the pond, should I move some?
No! There is no such thing as too much spawn or too many tadpoles, it will naturally balance out over time.
During spring amphibians return to ponds to breed. It may seem like the pond is ‘overcrowded’ or that there is ‘too much’ spawn but this is a completely natural phenomenon, typical of amphibian populations around the world. While some years may be particularly good for breeding amphibians, many people report that in subsequent years the numbers are not sustained and they then drop down.
Large numbers of breeding frogs can result in enormous ‘rafts’ or ‘mats’ of spawn being laid, sometimes covering the whole surface of the pond. This is natural and will not result in your pond being ‘over-run with tadpoles’ or your garden being ‘over-run with frogs’ later in the year.
Amphibians lay large numbers of eggs as a natural way to counter the range of predators that eat spawn and tadpoles. It’s thought that around one in fifty of the eggs laid in the pond will actually make it out of the pond as a froglet. The rest will be eaten by pond predators that might include fish (if present), dragonfly larvae and newts. Having large numbers of tadpoles can also lead to intense competition between individuals for food, meaning again that numbers of tadpoles will naturally thin out.
Of the froglets that leave the pond, only a handful will make it to adulthood – the rest will get eaten by other predators including grass snakes, blackbirds, crows, magpies, hedgehogs, foxes and badgers. We advise that you refrain from interfering with the natural events that occur in your pond. Instead, enjoy it – frog numbers may not be as high in future years.
Stop the swap!
We advise that you don’t move amphibians or their spawn away from your pond as by taking them to a different pond you may unwittingly transfer various diseases and invasive plants. Also, many amphibians may try to return and they will suffer if placed in an unsuitable area. Do not release spawn, tadpoles or adult amphibians into the wild or into public water bodies such as rivers, canals reservoirs or country park/nature reserve ponds.
There is no spawn/are no tadpoles in the pond, what’s wrong?
No spawn could be related to the weather or an abundance of predators.
Depending on the weather, it may still be too early for amphibians to be returning to the pond. Frogs and toads breed in the spring when they migrate towards water; this migration is weather dependent (they prefer mild, wet evenings) and so is determined by location – it tends to occur later in the north and east of the country and earlier in the south. In the past there have been reports of spawning amphibians in December!
In some cases, lack of breeding amphibians in your pond could be the result of a population decline locally. This might be an indicator of pond loss – ponds form ‘stepping stones’ for amphibians across a landscape and if they disappear, so can local populations of amphibians. Their terrestrial habitats are just as important as amphibians spend a lot of time on land, foraging, sheltering/hibernating and colonising new areas. If these areas or ‘corridors’ have been blocked (by a new road or even a fence) or destroyed (through development), the route to your garden may have been lost.
Amphibian populations can fluctuate dramatically year on year, so having years with low numbers of amphibians can be a natural phenomenon and nothing to worry about. If no breeding adults appear in your pond, there may be other juvenile amphibians in the area that will turn up next year as breeding adults (frogs take two or three years to reach breeding age). An outbreak of disease in previous years or a particularly hard winter could also impact on numbers returning. You may be tempted to introduce some spawn from elsewhere to try and help your local population but we advise against this. By moving spawn you can accidentally introduce diseases and invasive pond plants.
If you have seen frogs but no spawn it’s important to remember that all amphibian life-stages form a natural part of the food chain. Spawn is probably the lifecycle stage that is the safest from the attack of predators, despite the numerous predators in and out of the pond. Spawn will also sink below the surface in deep water so it may not be visible. Occasionally spawn can sink below the surface and die; it is particularly susceptible to late frosts.
Where can I get spawn/tadpoles for my pond?
Movement of spawn/tadpoles between ponds is potentially risky and should be avoided; ponds should colonise naturally.
We do not recommend moving animals or their spawn around because of the threat of unwittingly transferring various diseases and invasive plants. In most parts of the UK, amphibians (particularly common frogs and smooth newts) should find their own way to good quality ponds. It can take two years or more for a pond to colonise so do not be concerned if your pond is not immediately inundated with amphibians. Also, if amphibians don’t arrive of their own accord there may be a reason for this and it may not be appropriate to introduce them artificially.
What the law says
All wild, native amphibians (adults and spawn) are protected against sale/trade. Please inform us if you see amphibians being sold (including on internet auction sites); it is legal to buy/sell exotic or captive bred individuals/spawn though this should be stated in the advert.
Should I feed the tadpoles in my pond?
This is not usually necessary unless the pond is very new.
Ponds normally provide enough food for tadpoles without any need to supplement their diet. Newly hatched tadpoles are herbivorous and feed on the algae that grows on plants or on rocks in the pond, particularly those exposed to the sun. In the latter stages of their development they become omnivorous, feeding on decaying matter in the pond and tiny creatures such as water fleas (Daphnia).
Some people choose to supplement tadpole diets with boiled lettuce/spinach (to start) or fish flakes (for cold water fish). This approach is undoubtedly beneficial, especially if numbers are high or if the pond is relatively new, though adding too much food can pollute the water and may lead to unwanted algal blooms.
Should I protect the spawn from frost?
This is your decision, some will probably survive but you may choose to help.
Spawn can be affected by cold weather. If a layer of ice forms over the surface of the spawn it could die, though the eggs at the bottom of the clump may survive. Sometimes icy weather can interrupt spawning, in which case a second batch of frogspawn may turn up in your pond once the cold weather subsides.
Newt eggs and toad spawn tend to be more protected from frosts as they are laid slightly later in the year and deeper underwater.
Some people choose to take measures to protect spawn from icy weather by using a pond cover or by removing some of the spawn and keeping it somewhere slightly more protected (in a bucket of pond water in the shed, for instance) until the cold weather has passed.
Is it ok to use a pond filter/fountain whilst there are tadpoles?
If possible it’s probably better not to
It depends on filter size, mesh size and capacity. It is probably best to restrict the usage until tadpoles leave the pond in June-July unless there is a good reason to do otherwise (pond is small, highly nutrient rich, with little plant oxygenators and without filter becomes stagnant and starts to smell for example). A well balanced pond should be able to keep good water quality without any filter.
I need to work on the pond, what shall I do with the spawn / tadpoles?
Ideally wait until later in the year but if work is needed urgently keep them out of the way in a container of pond water.
If possible, delay pond maintenance until late autumn (September/October), so that tadpoles have been given time to metamorphose and leave the water (and before adult frogs might be returning to the pond to hibernate). If you need to carry out the work more urgently, remove the spawn/tadpoles with a net and place in a tank or suitable container filled with pond water or rain water while you do the work. Carefully return them to the pond when you’ve finished. If you have refilled the pond with tap water, leave it for a day or so or consider treating the water before returning the spawn/tadpoles.
Occasionally tadpoles or newt larvae remain in the pond over the winter and develop the following spring, so be sure to be check the pond carefully before starting work at any time of year.
If you are considering filling in your pond because of safety concerns we advise you to consider installing some simple safety precautions for the pond instead. Removing a pond can be very detrimental to local wildlife, particularly as adult amphibians will have nowhere to spawn when they return the following spring.
There is no organisation that will remove animals from your garden.