If you are lucky enough to have a koi pond there are several threats to your fish. One of these is most certainly a hungry heron. Koi provide a nutritious and substantial meal for herons and you could find that your fish are disappearing at an alarming rate. But what can you do about the situation? Could you kill the thieving heron, for instance?
Protected Birds
Unfortunately, the laws of the UK place herons much higher up the pecking order than your koi. Herons are protected under the Wildlife and Countryside Act 1981. It is an offence to kill one of these birds. Whilst commercial fisheries may occasionally be granted a special licence to cull herons, anyone keeping koi in their garden will have no such luck. Ornamental fish are not a priority for preservation. Even if a thieving heron is removing thousands of pounds worth of fish. So, bumping off your neighbourhood heron isn't really an option unless you want to land yourself in a whole lot of trouble. You would face a sizeable fine or even a prison sentence if you were to leave out some poison, set a trap or let loose with an air rifle. Any corpses on or near your property would almost certainly spark an investigation so less drastic measures are in order.
Protecting Your Koi
The more visible your fish are, the more likely they are to be taken by a heron. Some keepers net their ponds and provide their fish with covered areas in which to hide from the birds. Netting or metal caging can work and will also protect your fish from cats. Some koi enthusiasts have resorted to redesigning their ponds to feature steeper sides as this can prevent the herons from perching on the edge and doing a little fishing. But there are downsides to this approach. Steep sided ponds are hazardous to hedgehogs which can fall in and find themselves unable to climb out again. You wouldn't want to find a deceased hedgehog in your pond. Indeed, steep sided ponds aren't at all wildlife friendly.
Scarecrows
Herons might like koi but they are wary of people so a scarecrow which looks suitably human might do the trick. This should be backed up by a regular human presence as the birds will eventually cotton on to the fact that the scarecrow isn't a threat. Even the average bird brain is capable of working that out! Herons are most likely to pay your pond a visit at dawn or dusk so these are good times to be at your pond if you want to deploy scare tactics. By the way, there is no point investing in a plastic heron to scare off the birds. Heron ornaments of any kind are likely to attract the birds to your pond rather than keep them away. So there you have it. You can't kill or injure herons so you must either scare them off or shield your pond. If there is a heron in the area and it has found your garden, you could be in for some serious trouble.