There are probably few things quite so disheartening than having established your beautiful fish or wildlife pond only to see its inhabitants decimated at the claws, jaws and beaks of hungry predators. Sadly, whatever life your pond contains, there will be something which considers it a tasty snack. Some of the smaller predators are virtually impossible to keep out, so a certain amount of losses of fry and tadpoles will, sadly, always remain a constant part of pond-keeping. However, the odds are more in our favour with the larger diners who visit – and a spot of deterrence can often make all the difference.
Small but Persistent
Insects number amongst some of the most hungry and persistent mini-predators in the pond. While dragonflies darting above the water may be one of the most welcome sights of summer, their larvae make inroads into anything smaller than themselves which happens into range of their powerful, extensible jaws. Large enough to take young fish, tadpoles and even small newts with ease, they can have quite an effect on the pond – particularly since some species spend up to five years in the water before changing into their adult form.
The great diving beetle is another ferocious predator with a large appetite for small pond animals, both as a 4cm long adult and as larvae, which may even be a little larger. The young take about a year to develop into adults, which then are able to fly – usually at night – to find suitable homes. They tend to prefer densely planted ponds and often bury themselves in the sludge at the bottom during the worst of the winter.
Herons and Other Unwelcome Guests
Of the larger predators, the Grey Heron (Ardea cinera) is probably the biggest threat to frogs and fish being easily able to consume a third of a kilogram of either in a day – and double that if there are chicks to be fed – though foxes, cats and even dogs can also be a nuisance. Effective deterrence is the only practical way to deal with the herons, denying them the easy meal that they have come to collect. The most usual ways to do this involve making it physically impossible for them to get at the fish – though this is not easy given their wickedly long beaks – or stopping them being able to strike in comfort from a good vantage point on the bank.
Nets and grills across the pond are often used to good effect, keeping the bird out of striking distance and netting fences around the perimeter can also help, since herons typically land on the ground and then walk up to the pond to hunt. However, both of these solutions can sometimes be a little unsightly and spoil the look of the water feature. One way around this is to construct the fence out of twine, tied to suitable supports; alternatively a selection of manufacturers produce these as kits, which tend to look quite unobtrusive. A mini-electric fence specifically designed for pond protection is also now available, to reinforce the message with a bit of a jolt.
Other high-tech solutions include trip-wire activated scarers and audio devices triggered by Passive Infra Red (PIR) motion sensors, which reproduce the sound of a gunshot and a heron alarm call – though neither is likely to endear you to any close neighbours. At the other extreme – and a good deal quieter – an old-fashioned scarecrow may be just as effective, especially if the heron also sees real people around the pond from time to time. The one thing virtually guaranteed not to work, however, is to put a plastic heron alongside the water, in the mistaken belief that it will appear to be staking out its territory and so put off intruders. Sadly, this is more likely to draw every passing rival’s attention to the richness of spoils to be had for free!
Cats, foxes and even the occasional stray dog can sometimes also prove a problem. Strong grills and fences may also be helpful in deterring them, while the use of wobbly rocks around the pond margins is said to put off cats – though there is the danger that next door’s moggie simply dislodges them and they end up falling in the water.
A variety of deterrent devices are also available based on PIR sensors to trigger a response to the unwanted arrival. Automatic water-jets, such as the Contech Scarecrow, connect to a hosepipe and deliver a powerful squirt towards the intruder on detection, while ultrasonic devices, such as the Fox Repeller, are designed to produce sounds at a frequency that foxes – and cats – find unpleasant.
Keeping pond life safe from predators is always likely to require a fair bit of effort. However, if you do succeed in making life sufficiently difficult for the predators, the chances are they will be off looking for easier picking elsewhere and your precious fish, newts or frogs get to live another day.