Predators

: Quite possibly the most common Pond Offenders, this beautiful, but deadly, bird can grow to a height of 4 1/2 feet tall.  They hunt both day and night, usually alone, but will hunt together if the food source is abundant. They can eat fish, frogs, turtles, young birds and bird eggs, snakes, and insects as well as mice, moles, gophers, and other small mammals. They wade into water up to their bellies, curl their long necks into an S shape (thanks to specially shaped vertebrae) and wait patiently for an opportunity. Once they have spotted their target, they strike at high speed and either clamp or spear their food.  A shake, a toss, and a gulp and your Koi is history.

Signs of a attack from a Blue Heron can include: fish completely gone or fish speared and left on the banks of the pond or injured in the water. These birds often spear fish too big to eat and discard them with indifference. As with all predator attacks, the remaining fish will often be in hiding and scared to surface. Even when you come to the pond to expect your wet pets to recognize you and come up, often they stay wary and keep to the depths of the pond.

Most common deterrents:

Fishing line strung over the pond: This seems to be one of the best deterrents. Ponders take normal fishing line and string a crisscrossing pattern 4-5 feet above their pond and down to the edges. This almost invisible trip line acts as a confusing invisible barrier that perplexes the bird as it attempts to fly in low to land near pond. The act of hitting the lines startles the bird so badly the bird abandons all attempts to fly into the pond and leaves.

Fishing line strung around the perimeter of the pond: Often these birds will land in nearby trees or another vantage point to carefully check the area for danger before making a approach to the pond. As they fly down from their vantage point, a slow and methodical path is made to the pond. In this case, fishing line above the pond would be no help. However, by stringing fishing line 1 foot off the ground and along the perimeter about 1 foot back from the water edge will serve the same startling effect as the fishing line in the air. This invisible trip line is all it takes to baffle these birds and negate attempts to spear your fish.

Netting the pond completely: Some ponders go the ALL OUT approach and install netting across the entire pond. Quite the eyesore, but for some the only peace of mind that in no way can a Blue Heron find an opening to take valuable fish. However, depending on the netting size (ex. 1” square gap or larger) and if the netting is laid over the pond by just inches, the Blue Herons will often still manage to spear fish through the netting gaps, only to leave the fish injured as they can’t pull the fish through the mesh. To deal with this, position the net several feet above the water's surface to increase the distance the bird must deal with. Don’t think you can cover most of the pond and leave a small area open. These birds are smart, and will walk the perimeter looking for the weak spot to exploit.  (See one way to build your own net here)

Water scarecrow devices: These are basically a sprinkler head with built in motion and heat sensor detectors. You connect this to a water hose and turn on the water. On the back of the water scarecrow is a knob you can adjust for sensitivity of what moves in it’s range of detection. You can also adjust for arc of spray and left to right coverage of area of spray. When an animal moves within the selected range of detection, the water scarecrow picks up the heat difference between that object and the background. Along with the motion, the sprinkler automatically fires off a controlled burst of about 1.5 cups of water. The water scarecrow then resets itself. It runs off a 9 volt battery. The action, water and noise the device creates is often enough to deter unwanted pests. The only downside I can think when using this device on my pond, is remembering to turn it off when walking up to my pond. Let’s just say I know it’s HOT here in TEXAS, but when it comes to getting soaked, that’s what the pool is for!

Other Methods, possibly less effective:

Heron Decoy:  Some ponders believe that placing a fake heron beside their pond would deter a live heron from visiting, since these creatures are solitary hunters and respect one another’s space. I have doubts of the effectiveness of this tactic, as I have seen multiple herons feeding in the same area on several occasions.

Fake alligator heads:  The idea being that birds will stay away from one of their natural predators. This may be another dubious tactic, as many of these birds, especially in the southern states, are accustomed to large reptiles. In the wild they exhibit a healthy respect for these toothy beasts, but they have also developed a tolerance and are able to hunt and coexist with them.

Both of these methods have their believers as well as skeptics.  They may be worth a try if you are having a problem.

Even though many new ponders feel it necessary to declare war on any cat in their area, most cats pose no threat.  Maybe it’s the memory of all those old cartoons with alley cats feasting on fish that makes us think that ALL cats are fish eaters. The truth of the matter is that most of these outdoor cats don’t have the fishing skills, nor the desire to get their paws wet.  Most don't even care to expend the energy when they know their owner puts food out for them. I have seen cats come around my pond, sit quietly on the edge, and gaze into the waters as if they are enjoying the motion and movement of the fish. They treat the pond more as a huge water bowl ... could it be the delicious, fishy tasting water?

Wild, Feral Cats may, occasionally, pose a threat to pond fish.  Please consider Trap-Neuter-Return (TNR) if you have a Feral cat in your neighborhood. Rather than remove the cats and take them to a shelter (where these unadoptable cats are usually killed), you can allow these spayed and neutered cats to return to their outdoor environment. Because they are rodent specialists by nature, and you will also be supplementing their diet with cat food, they should leave your pond fish alone. Visit Alley Cat for more information. 

That's right! Those big, croaking bull frogs can also be the culprits when smaller goldfish go missing. These larger species of frog have a voracious appetite and a even bigger attitude. When it comes to lord of the lily pads, these guys are it.

It's been witnessed that these frogs have attacked small birds as well as cannibalize other smaller frogs! Not to declare war on all bullfrogs, but just keep that eye out on those larger mature bullfrogs. You never know, you might have to regress to those days of yesterday, roll up the pant legs and do some FROG HUNTIN!