herons and koi

Discussion in 'Garden Pest Management and Identification' started by Denise, Apr 22, 2008.

  1. Denise

    Denise Active Member

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    I have been reading with interest the thread concerning raccoons and how they can destroy a pond and what can be done. So far, we don't have raccoons in our pond although they are rampant where we live. (maybe my two dachies have marked their scent around the pond and the raccoons don't like it, I don't know) We have another problem and that is herons. We lost many of our koi last summer to heron(s). They are very bold and simply walk into the pond. We have tried a fake heron (which has to be moved daily), we have 'live' dogs who roam around, and for the past winter we have netted the pond making it look like Fort Knox. I want to un-net the pond soon so I can do an algae clean up and place iris' and other plants back into it. But I am scared that once the herons notice (and they do notice when the net is off) tha the net is off, the remainder of the fish will be eaten. Has anyone tried the "scare-crow" water detractor? What about an electrical fence system whereby three rows of electrical fencing hangs out over the pond? (not very aesthetically pleasing I think) I understand that they must "walk" into the pond.
     
  2. lorax

    lorax Rising Contributor

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    My grandparents tried everything and ultimately gave up on trying to keep herons out of their pond, and instead started stocking with really cheap fish fry (they just bought a bunch of trout fry) to encourage the herons to take up residence instead. This had the added benefit for them of deterring raccoons; I'm not sure how exactly that worked, but it did. Your dachsunds are probably doing the trick for you.

    And I've seen herons that know the depth of their home ponds make wet landings, so I'm not sure that fencing it off would work for you anyhow....
     
  3. Creeping Jenny

    Creeping Jenny Active Member

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    I recently saw on a home show someone who had the same problem. Apparently now they make "decoy" koi fish (wonder if they are called de-koi ... ohhhh groaner, sorry) anyways, they stay just below the surface of your pond. The heron will peck at them first, realize they are fake and leave. I have no clue if it really works but they say it does.
     
  4. Denise

    Denise Active Member

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    Thanks Jenny. That is indeed great news. And like you, I groan at the name a little bit --but a perfect name really and a very 'catchy' idea!!! I'll look on the internet to see if they are advertised somewhere. dt
     
  5. Creeping Jenny

    Creeping Jenny Active Member

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    no problem. I wish I could tell you more. Maybe searching the HGTV website... let me know how it works out!
     
  6. lorax

    lorax Rising Contributor

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    What a good idea - kind of like painting rocks red and strewing them in your strawberry patch to keep the crows off.
     
  7. Creeping Jenny

    Creeping Jenny Active Member

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    I thought it was pretty clever.
     
  8. Michael F

    Michael F Esteemed Contributor Forums Moderator 10 Years

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    If they are familiar with the areas of safe water depth in a pond, they will readily land direct in the water without having to walk in. They only walk in where they don't know how deep the water is.
     
  9. Ron B

    Ron B Esteemed Contributor 10 Years

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    Raccoons here eat out of dog dishes and sometimes walk around in broad daylight so I'm not sure the scent of dogs is going to be a strong deterrent. I've had them walk past me and up the driveway while I was standing there with the hose. Another time, after leaving a friend's small urban house a couple came down the steps behind me and went up the block, down the middle of the sidewalk, like two humans (this was at dusk, rather than during the day). During another visit to this same friend's house yesterday evening I encountered a racoon poop in the middle of his equivalent of a back lawn (it's not grass). The neighbor's full-sized barking dog was letting me know what it thought during this time.

    The nearest serious koi outlet (offerings include $5,000 imported specimens) has netting all the way across their outdoor tanks. Otherwise herons come and poke the eyes of the carp out and take holes out of their backs.

    It's always just a meal to a predator, no matter what the prey is and how much it suffers. If you put conspicuously colored fish in a little pool you have laid out a banquet.

    In pursuit of more natural foods herons here can be seen quite a ways out in open water, where there are shallows they can stand in.
     
  10. Olafhenny

    Olafhenny Active Member 10 Years

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    Hi Denise,

    If you only have herons to content with, you are a very lucky lady. I live in a gated community with a pond, which is slightly larger than an Olympic size swimming pool. We are battling kingfisher (capable of consuming 8 – 12 fish/day), heron, diving ducks as well as an osprey, which has been visiting repeatedly each day recently. Our pond is of course too large to cover with netting, so all we can do is to discourage the predators. Therefore our defences consist mainly of water lilies and a fountain in the middle of the pond. We only have about 6 to 10 koi in breeding age (prime being 4 to 9 years). I practically know 6 of them by name, but I suspect, that there are more of them, which do not come to our patio, which reaches over the water. They appear to prefer certain spots, which they do not like to stray from.
    In October 2006 I saw an estimated 200 yearlings (Generation 2005), which would be too big for kingfisher next spring and I was elated. Then late October the diving ducks moved in on their southward migration and stayed until mid November. I have seen only one koi of the 2005 generation since.

    This spring I estimated about 300 from the 2006 generation, clearly to big now for the kingfisher and hopefully also big enough to make them hard to swallow for the heron. That most of the pond is about 5 to 6’ deep also helps. Therefore I can foresee a substantial breeding population ahead in two years and beyond.

    Now, to your problem: You can get fairly fine but strong netting in your friendly garden shop (I got mine at Home Hardware), which should barely be visible from more than 10 feet away, thus extenuating the fort like appearance. Just do not let the netting hang into the water. If necessary suspend it in the middle with a block of Styrofoam. It is all just temporary, until you get some water lilies going. The best growers are the white ones (nymphaea odorata alba). I have one planted into a tomato cage, raising it from the bottom, because the pond is too deep, which attained a diameter of 14 feet in just two years. Next in line, at least in our pond is the red/pink variegated ‘nymphaea attraction’. The yellow ‘nymphea marliacea chromatella’ grows more slowly but adds nice colour.

    This is getting much too big a post, but if you wish, I can write you more per PM, but it would help to know the size and depth of your pond.

    Best and good luck,
    Olaf
     
  11. Michael F

    Michael F Esteemed Contributor Forums Moderator 10 Years

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    Herons can take much larger fish than ducks (most diving ducks actually don't eat fish at all, only mergansers do so). Cormorants and Ospreys can take even larger fish than herons, though, and otters even larger still.
     
  12. Olafhenny

    Olafhenny Active Member 10 Years

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    Thanks Michael. I was under the distinct impression, that all diving ducks learn how to dive for the sole purpose to eat our cherished koi. ;)

    Kidding aside, I did suspect that the other ducks, I was told, that they were gadwalls, did half of the damage, so much so, that, when I recently learned that gadwalls were veggi eaters, I thought, that I would have to wait for late October, to re-identify the suspected burglars. After your post I did some more researching, and have come to the conclusion that the visiting (hooded) mergansers are indeed solely culpable for all the stock loss, which occurred after the osprey and the kingfisher had moved south.

    That is not particularly good news, because we had two female mergansers visiting of and on for about 4 weeks now. The first time they dropped in during spring.

    Thanks again, Michael, I learned something very useful,
    Olaf
     
  13. Michael F

    Michael F Esteemed Contributor Forums Moderator 10 Years

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    No problem!

    Hooded Mergansers usually only take quite small fish, typically around 2-5cm long; Common Mergansers will take slightly larger fish, but still nothing like as large as herons or cormorants do.

    I suspect to find the culprits, you may also need to see what is visiting at night. Herons at least are often at least semi-nocturnal.
     
  14. Denise

    Denise Active Member

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    Thanks for the various suggestions about herons and koi in my pond. I bought some floating koi which we have set up in the pond, but what worries me is that the live koi are very much attracted to the fake koi. I feel the koi swimming around the fake ones, inviting them to play are 'sitting ducks' when the herons stealthily wade into the pond. Easy pickins' I'd say. see photo
     
  15. togata57

    togata57 Rising Contributor

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  16. Michael F

    Michael F Esteemed Contributor Forums Moderator 10 Years

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    If something is happy to dive into a pond to take fish, it won't be put off by a shower of water!
     
  17. togata57

    togata57 Rising Contributor

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    Please note that I did write 'might be good for discouraging' and 'For a while'.
    Nowhere did I state that I believe this to be a permanent or comprehensive solution to predation.
     
  18. Michael F

    Michael F Esteemed Contributor Forums Moderator 10 Years

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    Yep, but I doubt it would work even as a temporary solution.
     

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