THE BIRD WARS...... We all love animals. That is a common attribute of "Pond" people. However, when the wildlife we have attracted to our backyards begin killing and eating our relatively expensive pet fish, we are faced with the necessity of discouraging their visits. Such is the case of the Great Blue Heron. This wading, migratory bird, whose wingspan can approach six feet, is a virtual Koi killing machine. Fish too large to be eaten are speared, and left to die, much like the way a weasel will kill every roosting hen in a chicken house. In addition, the heron's fecal matter contains a myriad of pathogens that are likely to show up as disease in any fish that remain. If a heron finds your unprotected pool, your fish are as good as gone. Even with the best known methods, understand that heron are quite adaptable, and still may eat your fish. Here are some strategies that may help you win the Bird Wars:

1.     Use an anti-heron pool design. Do not build your pool with any shelves , shallow areas, beaches, etc. Instead, uses steep walls down to at least 36 inches to discourage herons from standing in the water. Be forewarned, however, that such design could sacrifice safety should a young or old person fall into the pool.

2.     Use barriers:

1.     To discourage herons from wading into your pool, string a heavy monofilament all around the pool at a height of fourteen inches.

2.     Cover the pool with bird netting. Raise the netting so that it is at least 20 to 25 inches above the water level. Netting the pool is especially called for in the fall and early spring when surface coverage of plants is at a minimum.

3.     Place items in the pool that your fish can hide under.

4.     Enlist a natural enemy. Get a dog that hates herons.

5.     Use Decoys. Obtain a lifelike statue of a heron and place it at the pool. Move it often. Heron are solitary hunters and dislike company.

6.     Build and use the "Heronizer" While the bird netting barrier is probably the most effective heron deterrent, the use of motion detectors to operate startle equipment can help. Motion sensors can be used to operate sprinklers, noise makers such as bells or radios, or create movement to scare away predatory intruders. My version of the motion sensing heron startle system is the "HERONIZER."

The HERONIZER consists of a motion detector from a common security light and several low voltage startle options. Here is the parts listing for the basic HERONIZER:

Security light, Regent model MS35 $10.84

Adapter 1/2 PVC to 1/2 pipe (2) at .19 $.38 P>Ell 90 degree 1/2"PVC (2) at .15 $.30

1/2 PVC PIPE 10' $.86

Riser, black poly 1/2" x 8" $.44

Ceiling box, non metallic B620H $2.13

Transformer, (Doorbell) 24 volt Trine #125C $10.68

Hose washers $0.98

Coupling, brass, male hose to male 3/4 pipe. $1.83

Coupling, brass, female hose to male 3/4 pipe. $1.96

Rainbird pulsating waters sprinkler with metal spike #SK-5 $5.86

Rainbird water valve #CP075 3/4 auto inline $9.97

Wire nuts (four) $0.60

Power cord, '14 -2 type UF electric wire, 10 feet. $1.45

Electric plug, male (Lowes 72590) $1.63

Miscellaneous screws, etc. $0.50

Silicon caulk, GE $3.96

Thermostat wire, 2 conductor, 20 feet $1.80

TOTAL $50.41


The basic HERONIZER consists of a motion sensing device and an electrically operated water sprinkler. The HERONIZER can be used to operate more than a water sprinkler, however. It can operate any accessory using 12 or 24 volts AC, such as a bell, buzzer, or with rectification, small DC motors to produce movement to disturb predators.

Here is a photo of the main parts.

Begin by assembling the water valve/sprinkler component.

The water valve/sprinkler assembly is fairly straightforward and should not present any problems. The completed assembly appears as depicted in this following photo.

The completed sprinkler/valve assembly

The trickiest part of the sprinkler/valve assembly is adjusting the sprinkler to send a level stream straight out across your pond, rather than up in the air as is it's ordinary function. This is accomplished by using the following parts: Two 90 degree 1/2 PVC ells, two 1/2 female pipe to 1/2 PVC adapters, and three 1 inch pieces of 1/2 PVC pipe and some PVC cement. The parts look like this:

First, glue the parts as shown here:

Then assemble as shown. DO NOT glue the final connection.

Fit the two parts together.

Attach a clamp as shown so parts will not come apart when pressurized by water.

Attach hose and using the manual switch on the water valve, operate the sprinkler.

Adjust the unglued connection to vary the water nozzle angle. Remove from water and using a magic marker place a mark on the parts for alignment after glueing.

Remove the clamp. Apply PVC cement and glue the pieces together taking care to position the alignment marks.

Paint the white PVC a dark brown.

The sensor assembly is a little bit more complex.

This is what the unaltered sensor wiring will look like.

First, cut the wiring as shown.

Pre-drill for a tap screw.

Install a small tap screw.

Flatten the bracket so it can be pushed into the ground.

Seal the box with silicone caulk.

Wire the AC power cord. The black wire from the cord should attach to the single black loose wire coming out of the sensor. Attach the white wires together. If you desire an ON/OFF switch, wire it into the black wire coming from the power cord. I suggest that you arrange a remote switch so that you can turn on and off the HERONIZER a safe distance away. Addition of a pilot light, either at the remote switch location or on the unit itself is helpful both to warn you of the system being armed but also to give you peace of mind at a glance that your system is on.

Attach the transformer black wires, one to the other white wires and the other to the black wire coming out of the sensor that originally went to the floodlight sockets.

Assemble the transformer into the plastic ceiling box.

Remove the plastic nuts from the floodlight holders and remove them from the sensor. Place 1/2" plugs in the resulting holes. You may have to crimp the springs on the plugs to obtain a tight fit.

Attach the thermostat wire to the transformer, selecting either 12 or 24 volts AC.

This is what the completed sensor looks like. The blue plastic box and bracket should be painted dark brown.


If you've gotten this far, you will have a versatile motion detection device that can actuate a number of different apparatus to help in dissuading predators, most specifically, the Great Blue Heron. Because of the module style construction, you can even operate a tape recorder or motorized scaring device with the sensor, by incorporating a 12 volt AC relay.

To operate the sensor, place the function switch on "test". Other settings will cause the detector not to operate during daylight. This will provide a 4 second operation each time movement is detected. Turn the sensitivity up as high as you can without spurious signals, and avoid aiming at waterfalls.


One caution: Not all security lights (even the same model number) act exactly the same when first turned on. Many will activate immediately when turned on and then shut down in ready mode to start up again when energized by motion detection. Others may not do anything when turned on, but still be active for motion detection. I say this in order to help you avoid getting wet!

You may notice an increase in performance if you remove the snap on deflector on the top of the sprinkler.

If you decide to build the HERONIZER please let me know how it works out for you. I am building four of them at about the same cost as one commercially produced motion detector/sprinkler device.

Note: In operation, if the power goes off and immediately back on, your heronizer will spray water constantly until turned off. Wait 4 seconds before turning back on and the cycle will self adjust.