COMBATING POND PREDATORS
By Dayleen Van Ryswyk aka “The Koi Lady”
Now that the weather has stabilized, hopefully the issues with string algae and green water are settling down. I know that in one of my ponds that seem to be a magnet for string algae, it’s almost gone…thankfully!
Like most ponders I seem to always have room for “just one more Koi”. Last week I added a few new little guys to one of my ponds that were home to mostly large Koi. With in a day the Great Blue Heron was there and took two of them. Thankfully I interrupted his meal and stopped the all you can eat buffet at only two fish. I immediately grabbed my fishing line and some bamboo poles and started stringing the line around the perimeter of all my ponds (now that the Heron has found me.)
Great Blue Herons are a very tall gray/blue bird that can stand up to 5 feet tall and are a serious predator to many local backyard ponds. Herons land on the ground and walk into your pond to feed. Because of this behavior, they can actually be kept out of your pond fairly easily. Heron’s typically go after a size of fish that it can easily stab with its beak and then swallow whole. Something in the 2”-8” size is what they usually go for, though the large fish aren’t safe either because the Heron will still stab the large fish and kill them even if they can’t lift them out of the water and eat them.
The first step to protecting your pond is to get yourself some sturdy poles, either bamboo or re-bar work well. The re-bar is stronger and would probably be better for a permanent solution and if you spray paint them black, they blend into the landscape really well. Whichever you choose, you want them to stand about 2 feet tall once poked into the ground. Bang them into the ground with a hammer all around the perimeter of your pond (every 5-6 feet) and then tie 40 or 60-pound fishing line to the top of the pole. Wrap the fishing line tightly (tying it but not cutting the line) from pole to pole around the perimeter and even criss-cross the line over the pond in several places to discourage them from trying to get over the perimeter barrier. Try to have the lines about 18”-24” from the edge of the pond so that the Heron can’t just lean over the line and stab your fish.
The reason the fishing line trick works is because as I said before, they land on the ground and walk into your pond. When they walk up to your pond they feel the line touch their legs and they see it criss-crossed over the water and it scares them because they fear being entangled in it. They would really have to be desperate to risk death when they could fly over to your neighbor’s unprotected pond to get an easy meal. Once the Heron has found you, you’ll probably need to keep your protection up because they will keep checking in to see if it’s safe to fish. My Heron came back every day for 4 days after my fishing line was up, but he couldn’t get into the pond, so he left with an empty stomach.
Heron decoys (life like plastic Herons) are sort of hit and miss as an actual deterrent. Herons typically like to be solitary and usually won’t go where there’s another Heron. At least that’s the theory. I personally would rather be safe than sorry and do make sure that I now keep a decoy in use. It helps to move your decoy around every few days and if you spot a Heron flying over your pond checking it out. Go and move your decoy right away so it fools the real one into thinking someone is already fishing there. Also, mating season for Herons is February and March. Make sure you remove your decoy during those months or risk actually attracting them to your pond.
There is also a pretty cool device that works very well with Herons. It’s called the Scarecrow and it’s a motion-activated sprinkler that you set the zone and range of and it jets out a burst of water that scares the predator away. The Scarecrow is designed to work with other animals such as Raccoons, Dogs, Cats, Deer and Skunks etc. I find that with Raccoons especially, its effectiveness is only temporary. I believe that Raccoons are one of the most underestimated predators there is. They are extremely smart and will figure out most problems very quickly. I have actually witnessed them wash a fishes body in the stream of water coming from a Scarecrow sprinkler before he ate it. Raccoons can rally only be stopped with straight dropping sides to a depth of at least 3 feet. Raccoons can’t swim and hunt at the same time and won’t jump into something over their heads. They much prefer a shallow pond that they can sit in and fish from. Not having shelves or lily pots in reach for them to use as stepping stones is really the only way to discourage them from trying in the first place.
Now, if the Heron wasn’t bad enough. I had yet another predator show up a few days later. Believe it or not I actually had a Kingfisher “in” my fish house. He must have thought he had hit the fish jackpot when he saw 2000 fish in there. This particular Kingfisher was a small bird about the size of a Robin that had a long beak and was almost black with a white chest and a tuft on its head. I caught him with one of my fish nets and removed him but not before he got a small Butterfly Koi.
There are several varieties of Kingfishers but all are a diving bird. They usually sit on a tree branch or roof top to scope out your pond. The best way to keep them out of the pond is by using bird netting. The least obtrusive (visually) is the black ¼” by ¼” squares that comes in all kinds of sizes. When using netting, make sure that it is well above the water and pulled tight. You can make small holes in it for your taller plants to grow through if necessary.
Backyard ponds can sometimes be bothered by other birds such as Osprey, Hawks, Owls, Eagles, Bittern and Ducks to name a few. Other than the Ducks and Bittern (which can be kept out with netting) fishing line criss-crossed over the pond will help to keep the others out.
Sometimes Garder snakes can be a problem in backyard ponds. Though they aren’t usually a very big problem they can clear out some smaller fish. Their usual foods are tadpoles and frogs but I have seen them go after baby fish. I have no idea how to keep a snake out of a pond as they can get through just about every barrier. If you are losing fish to Garder snakes, maybe try catching them and releasing them back into a local wetland.
People are always asking me if Turtles are a good thing to keep in your fish pond and my answer is always “if you don’t mind your plants getting eaten and your fish being nipped.” Yes, Turtles eat fish. They are actually pretty good at catching them too. Though it may depend on the Turtle and whether it was raised with fish or not. I was given a pretty big Turtle last spring by a customer that was moving away and couldn’t keep him. Being the animal lover I am, I happily took him in. The plan was to find a good home for him (his name is Tony) but I have 2 boys, and well, Tony grew on us and is now our pet. Not only did Tony turn out to be pretty cool but he doesn’t eat the fish that live with him either. He’s more of a live and let live kind of Turtle I guess.
The problem with Tony is that he’s a Red Eared Slider and they are not winter hardy here. They are native to the southern US states and as such, needs to come inside in the winter. Not a big deal to me really but it is more work. Having a Turtle that was native to here and winter hardy would maybe be easier but it would also be illegal. Our native Painted Turtles are illegal to remove from the wild. Then there is always the added risk of Salmonella with all reptiles and Terrapins so hand washing should always be a priority if you have them as pets. In my opinion, Turtles are best kept to their own pond in a fenced yard that they can’t escape from.
There are too many possible pond predators to mention here but I have tried to cover the main offenders. When you build a pond always keep in mind the needs of the inhabitants and the likes of their predators and design your pond accordingly. To steal a line from a movie “If you build it, they will come” To what extent you’ll be bothered is anyone’s guess but knowing how to deal with life’s little issues, is the name of the game.