Predators and Pests

Adding a water garden or fish pond to your landscape is a terrific way to bring a natural element to your home. Nearly all outdoor water features will eventually be visited (or invaded, depending upon your perspective) by local "wildlife" or domestic animals. Just as water draws our attention, so too will it attract the attention of passing animals. Pond owners must consider this because some visiting creatures, particularly birds, are very good at capturing and consuming fish.

Giving thought to these matters should occur, ideally, prior to construction in order for you to get exactly what you want out of your water feature. Some pond owners may actually want to attract wildlife to observe native birds and other animals drink, eat, and bathe in the water. Some landscapers specialize in creating "wildlife gardens" which are designed to encourage wildlife for these reasons. The basic elements of a "wildlife garden" include shelter, food, and water which is why a pond is an ideal option. A "wildlife-friendly" pond should feature shallow areas (less than 12" deep) and a slow sloping edge to allow easy access for wading animals, birds, amphibians and reptiles.

Conversely, if you do not want to attract wildlife, your pond should feature deeper areas (24" or greater) in the center and nearly vertical edges that immediately go to a minimum depth of 15". Be aware that a pond constructed in this manner does not allow an escape route for animals that may accidentally fall in the pond. Avoid planting thick shrubbery around the pond to minimize areas that undesired animals could sneak around in. Ponds with significantly raised edges that create a "wall" effect are less likely to have animals enter. Koi pond owners suggest building an arbor or pavilion over the new pond so birds cannot see the pond as they fly over. This is not foolproof and may also limit the possibility of growing flowering aquatic plants. Snakes and other small animals are best discouraged by eliminating hiding places such as gaps in natural rock edging.

Owners of existing ponds may find keeping predators out very challenging, especially if the pond design makes for easy access. Animals are not easily deterred from a reliable food and water source. Even wild animals will eventually ignore motion lights, loud sounds, and shouting/ clapping pond owners. Shooting or killing them is rarely legal, practical, safe, or permanently effective. Live trapping and removal may work for some small mammals.

Fortunately for frustrated pond owners, the popularity of backyard ponds and the desire to protect pet fish has "spawned" a number of good ideas and effective products. There are fence kits that utilize thin wire and a small transformer to create a low electrical fence or cover. These are effective however may detract from the overall aesthetic and may shock unaware human visitors. Realistic heron and egret decoys will discourage actual herons and egrets because of their territorial nature. Maximize their effectiveness by moving them frequently. Pond owners can also provide hiding places for fish. Koi Kastles are small structures of aluminum frames covered with a fine black mesh that simply set on the pond floor to provide cover for all sizes of fish. Other objects such as cinder blocks can be placed in the pond and will serve the same purpose although may be less aesthetic. Providing shelter is a good idea though fish-eating birds are very patient and persistent and have been observed standing motionless for an hour or more until a hiding fish feels secure enough to make itself visible. A Scarecrow is a low profile post that is staked into the ground and features a motion sensor that operates on a 9-volt battery. A garden hose is attached and when the sensor is tripped (up to 35 ft. away), the device shoots a sudden jet of water in a set direction which wards off all types of creatures. It resets automatically and is ready again in seconds in case the predator returns. Some animals may eventually learn where the targeted area is so multiple units may be required for smarter animals such as raccoons. Overall this device can be very effective, especially if moved frequently. The only negative is the potential of dowsing unwary human visitors to the pond's edge. The most effective fish protective method for outdoor ponds is to cover them with netting. This option has an obvious negative impact on the ponds aesthetic and would also limit the growth and bloom potential of most aquatic plants. Regardless, netting could be used as a temporary fix until you implement better methods and would be perceived as a dead end by any animal.

Creatures known to prey upon pond fish include herons (especially the Great Blue Heron), egrets, hawks, eagles, kingfishers, owls, raccoons, otters, mink, turtles, snakes, bullfrogs, dragonfly larvae, other aquatic insects, and microscopic parasites. Fish are best protected from parasites and other diseases by maintaining proper water quality. It must be noted as well that pond fish including koi and goldfish will sometimes consume their own eggs and newly hatched fry.

Ornamental pond plants are sometimes subject to consumption or damage as well. The most prevalent culprits are smaller insect larvae such as the "China Mark" moth larvae. These bugs chew on leaves, especially water lily pads creating unsightly damage very quickly. Certain types of aquatic snails consume living plant tissues. Some larger caterpillars and worms occasionally damage lotuses, irises and other plants. Fortunately control of these pests is easily accomplished in most situations with proper maintenance; specifically regular pruning of damaged foliage which removes the bugs themselves. Plants can be treated with insecticides however this requires temporarily removing the plant from the pond which is impractical for most pond owners. Other creatures that can damage plants as well include larger koi, crayfish, turtles, muskrats, and grazing animals such as deer. Submerged plants are susceptible to damage during the winter by overgrazing pond fish. Plant Protectors can be helpful in avoiding this. Occasionally, larger visitors like raccoons or even the neighbors Labrador Retriever can crush, displace, and damage pond plants.

Pond owners often wonder how some of these smaller critters make it to their pond; there are several ways. Any time new fish or plants are added; animals or eggs can be unwittingly added. Birds and other animals will transfer eggs and small animals (hitch-hikers) when they move from one body of water to another. They may even be passed through their digestive system. Unknown fish may suddenly appear in a fishless pond as a result of any of these methods.

In summary, most current and future backyard pond owners will be confronted with some of these issues. It would be to their advantage to work with nature and develop whatever method or attitude for dealing with the pond's relationship with the surrounding outdoor world.