Garage door opener type sensor to trip a relay

@cmdrdick Since you already have a working system that turns on a radio, unplug the radio and plug in something else, maybe an agriculture electric fence. Could you plug the fence control box into the receptacle the radio was plugged into and see if that works?

@zander Considered, but I'll leave the electric fence as a last option. I'm trying hard to find a solution that won't trash the view of this pond / yard. Electric tape around numerous posts looks yucky. I have tried contacting the folks that make such systems, but they have been unable to tell me if they even work with tall birds.

@cmdrdick 

Two possible solutions I found on the internet.

Pond Net, black color easy to see through.
Motion activated sprinklers.

@cmdrdick No electric tape or posts, just run the wire on the top of the fence, when they land they get a zap. It will be almost invisible and the 'intensity' is adjustable on the better units.

@robotbuilder The problem with the net is they may get entangled in it. If scare tape was added in sufficient quantities it may work.

Another idea might be some trained bird of prey that would kill the invaders.

@cmdrdick I just noticed what those goldfish are worth, WOW.

@zander Great idea, I will definitely try that. They may learn to avoid landing there, like ignoring the radio, but it is worth the try.

@cmdrdick My second choice would be the sprinklers, but they have to be carefully aimed and tuned. The netting may get you some dead birds.

@zander Actually, they are Koi. A Japanese version of what we call Carp. They have been bred for color and after some 4000 years, the japs have turned them into a billion dollar industry. They have contests in Japan every year and the best of show is typically sold off for hundreds of thousands of dollars. You don't eat that fish. Google: How much does a koi fish cost in Japan?

They are colorful and great pets that live as long as we do. They will take food from your hand and follow you as you walk around the pond. That is my quiet place when the world becomes stressful. Watching a bird kill one of them adds to my stress level and may eventually cause me to use drastic measures. I'd just hate to kill something that looks as majestic as a Great Blue Heron.

@cmdrdick I know what they are; where I lived, we had a great lake connected to the bay and the marsh. The marsh and bay were full of them from people dumping them. The biggest native carp I ever saw was about 4 ft, hit by a propeller and killed.

A carp barrier was erected between the marsh and the bay some 20 years ago so the carp population has decreased about 75%. HOWEVER people have been irresponsible in releasing common goldfish (a carp relative) and they are small enough when sexually mature to slip through the barrier. The really bad news is they are even more destructive. Maybe you can send those birds there to help in the cleanup.

I tried using an animal trap wrapped with tape and hooked to a chain underwater. It caught one, then I didn't know what to do with it. I wrapped newspaper to make a soft club and went out and smacked the crap out of it while it tried to get even by harpooning me with it's beak. Damn, they are bigger than they look from a distance.

I then tossed a blanket over it and sprayed red paint on it's beak and let it fly away. It never returned. But, living in Florida means there will always be more of them. I've become Elmer Fudd to the feathered Bugs Bunny.

Maybe I'll make a pond inside the pool enclosure. Nobody ever uses the pool anymore and I'm tired of buying Chlorine. Then I can just put cheap goldfish or Tilapia in the outside pond and let the birds have at em.

@zander 

@cmdrdick

They did say the net would have to be pulled tight.

I would imagine a stainless steel mesh cover would also work unless too expensive to cover the 50'x50' area. I thought of doing that on a small pond we had that children kept falling into although I guess they would discover they could walk over the pond instead.

Carp were released in the Murray River Australia and have pushed the native species into rapid decline. As a child I could go out on the river and within an hour bring home a bag full of different species of Perch,  now nothing but Carp. Australia has been completely transformed by the many feral species introduced over the decades since Europeans invaded and took possession of the land.

Personally I would try the motion activated sprinklers on the pond. It could be a feature as well.

A pond inside the pool enclosure sounds like a great solution.

@robotbuilder @cmdrdick and also safer. I was just reading that the marsh I had mentioned had an event where low water levels and wind literally emptied the marsh and all the fish a few years back so now the carp are gone.

The sprinkler idea doesn't seem to have any effect. I have a tall sprinkler head at each of the four corners. I've seen them out there hunting in heavy rain. They live in those conditions so a light spray from my sprinklers isn't doing the job. I tried one of the motion activated sprinklers intended for these birds. It had no effect at all.

I'm seriously going to do the shock wire on the fence top rail at my first opportunity. If that doesn't work, then maybe the pellet rifle. Guns are legal here, but if a stinging pellet will work I won't go any further.

The problem with that is they see me coming and are in the air before I can get close enough to fire. They typically come at daybreak. A camo tent close to the pond might work if I want to get out there in the dark and wait every time one of them finds my pond.

Hey, this is taking up too much of Bills storage space and it no longer applies to electronics, so I'll end this discussion. Thanks guys for all of the suggestions.

CmdrDick