Blue Heron Deterrents

The reason your fish keep disappearing from your water feature


Today I’d like to talk to you about the Blue Heron.

The blue heron is an impressive predator. Maybe you’ve been boating on a lake and you’ve seen him on the lakeshore sitting stoically waiting for fish to come by, or maybe you’ve been canoeing in a river and seen them on the riverbank. Or maybe you’ve seen them fly by and wondered ‘what the heck is that thing?’.

More about the blue heron

With a seven-foot wingspan, the blue heron is very impressive to see. Being such a big bird, you’d be surprised that they’re only five or six pounds though due to the fact their bones are hollow like most birds.

While a beautiful part of nature, blue heron can be an unwelcome guest at Koi ponds. Let’s face it, we spend a lot of money on Koi, we get them to feed out of our hands, as they get bigger they get names. So we get close with the koi and they become our pets. So how do we deter this oppressive predator from taking our pets from our ponds?

Well first you need to know a little bit about them. So they’re protected by the Migratory Bird Treaty Act, which means you can’t take care of them like your grandfather would have years ago. They hunt day and night, they have photoreceptors in their eyes that allow them to see great at night. 90% of their time is spent stalking and just motionless just hoping fish will come by close enough. They have a lighting fast strike. On small fish they’ll grab with their beak and pick up the fish and flop it right down their throat.

Larger fish, unfortunately they’ll use that sharp beak and poke through the fish and then again swallow it hole. Because they swallow the fish whole you’re unlikely to see signs that a blue heron has been to your pond. Unlike other predators like a mink who will definitely leave signs of scales behind and you can tell when something has definitely been there. Blue heron will migrate south, but in our climate here in Pittsburgh, many times they’ll over-winter right here. So koi ponds are not safe from blue heron in the winter.


So what are humane options for deterring the blue heron from taking your pets from your pond?

1. Pond design

Most important thing is pond design. If you can have a deeper pond with steep walls, that can deter the blue heron from getting to your fish. But most municipalities require a fence for any pond that’s deeper than two feet.


2. Boater caves

Another way that we can design the pond is to build boater caves into the bottom of the pond, so that it creates a little area for the fish to go underneath the boater to hide away from the blue heron. And that can be effective.


3. PVC Drainpipes

Also a large pvc drainpipes  we can excavate into the ponds and disguise with rock so it looks like a fish cave so fish can hide underneath that structure.


4. Floating Seasonal Plants

Also, floating seasonal plants are also a good way to do that. We’ve talked about hyacinth and different types of aquatics that can be a good cover for fish. While not totally effective, it can help hide fish from the blue heron.


5. Decoys

There’s decoys like heron or you may have seen alligators. I have a decoy at my yard, and I move it every once in a while to try to fool the bird. But understand blue herons are a pretty uncanny bird and can many times figure these things out.


6. Monofilament

Monofilament line is another good way. So fishing line, take little landscape staples and put them around your pond, and then zigzag fishing line through the staples to cut off any entry areas for the blue heron. Note that you have to be pretty consistent in the way that you do that so there’s no big gaps that the bird can get through, because again they’re pretty good at what they do.


7. Netting

Netting is another way, but let’s face it, who wants’ to see a net over top of their pond. But if you have expensive fish that you care for and the blue heron is on a flight path where he visits you a lot, putting a net over top of your pond for the short term can be helpful, but again it’s unsightly.


8. Motion-activated water spitter

Another deterrent is a motion-activated water spitter that will shoot out a little bit of water when motion is detected. Important thing is to place it in your pond or area where you don’t get hit by it when you walk out to your pond every time.

So the blue heron, worthy adversary or a beautiful, cunning predator. You decide.