Another tool-using bird

February 3, 2011 • 7:38 am

It’s the green heron (Butorides virescens), a denizen of North and Central American wetlands and an accomplished fisherman. They are sit-and-wait predators, perching motionless on the bank or on a tree, ready to grab a fish by striking out with their amazingly long necks. (You can see this in the video below.)  The neck strike could be considered convergent with a snake strike!  Here’s a green heron in a normal position (photos from 10,000 Birds):

And the same bird at full stretch:

Here’s one fishing upside down from a branch:

Such lovely birds.  But the most amazing thing is that they use tools.  Some of them fish with bait, putting a piece of food or an object in the water and then snatching the fish that are attracted to it. Here’s a video of that behavior (ignore the cloying and patronizing narration—”Oh, what a clever bird!”).  Notice how the bird keeps repositioning his bait, like a fisherman casting his line over and over again:

That strike is fast!  You can see a different video and a different bird here; in this case the bird goes into the water for the catch, and gets a bigger fish.

Is the fishing behavior innate or learned?  The Animal Cognition site from Tufts University says this:

The practice of bait-fishing is rare among green herons.  The fact that few herons use bait-fishing indicates that it is not an innate behavior. [JAC note: I don’t agree; rarity doesn’t militate against innate-ness.] Moreover, the infrequency of bait-fishing suggests that the behavior is not culturally transmitted.  The roots of using objects to attract fish are unclear.  One theory suggests that herons are imitating human behavior when they use bait for fishing.  However, the fact that attempts to teach herons to use bait for fishing have failed suggest otherwise.

Another possibility is that herons learn to use bait for fishing through experience, i.e. the heron accidentally drops an object in the water and sees the object’s attraction to fish.  Some researchers believe that making the connection between dropping something on the water and seeing the crowd of fish that results and intentionally dropping bait into the water is very difficult.  According to these researchers, only the exceptionally intelligent herons acquire the skill of bait fishing.  The intelligence requirement accounts for the small percentage of green herons who engage in bait-fishing.  Other researchers argue that the reason for the infrequency of the behavior is that few herons actually have the opportunity to observe the results of dropping an object into the water.

37 thoughts on “Another tool-using bird

  1. Thank you for this, Jerry! The Green Heron’s absolutely the greatest avian photo subject in North America, always entertaining, and often amusing. I’ve been known to ignore rare birds when Green Herons are in the offing. The bait-fishing behavior must be pretty rare, though, because through the years I’ve probably spent hundreds of hours watching these guys, and never observed one engaged in it.

  2. Wow, I’ve never seen a green heron bait fish before. Of course, my experience with them is mountainous areas with rivers and streams, not ponds or estuaries. So bait fishing probably wouldn’t work so well…

    Sitll, it’s really neat to see it…

  3. At least one pair of these nests and successfully fledges a brood on the pond directly behind my house every year. They are cool. The have an other-worldly croak!

  4. About your internal note – the Tufts quote said the rarity indicates that the behavior is not innate. That could be consistent with your objection, couldn’t it? Because it’s a cautious claim – short of “demonstrates” or “shows” much less “establishes”?

    I’m not nit-picking, I’m just interested in these things.

    1. The proper term to use in this case would be “suggests”, not “indicates”. At least, that’s what my understanding of how the terms are used in scientific literature suggests.

      1. …and even then, it should be qualified with a reference to any study of the frequency of innate behaviors in birds.

        IOW, I agree with Jerry, it was an unqualified statement, not based on any literature I’m aware of.

    2. It’s one of those annoying words that’s used to denote both certainty and circumspection, depending not on context but on who’s using it.

      In general, I assume an assertion with the bare word, and suggestion when used with “may” (e.g. “the numbers in this ledger indicate you’ve been stealing” versus “the numbers in this ledger may indicate that someone has been stealing”).

  5. It might be the equivalent of a rat learning to push a lever. Push lever = food is not that hard to learn, and it can be done without any complex internal theory about bread attracts fish, etc. The fact that the bird seems to be striking the bread like it strikes the fish is perhaps evidence for this — maybe it all started at the duck pond, where the bird first learned that bread thrown by children wasn’t yummy, but then learned to associate it with fish, and then learned to throw its own bread in.

    Then again, we just saw crows etc. I think there may be some real brain evidence that corvids are smarter than other birds, but even average bird brains are far from useless, given the complexities of nest building, nest finding, migration, etc.

    1. Like those poor pigeons taught to do all sorts of crazed superstitious dances because they got random rewards. “Oh, food – what was I just doing? Head on one side – try that again – and again – and again – “

    2. The heron seems to realise that the bread needs to be as far out into the water as possible to attract a fish, it keeps pushing it further out. It also changes the position of the bread when it’s not having any luck in the first location. That seems fairly complex behaviour to me.

    3. It’s probably not striking the bread as it would a fish, because soggy bread takes a more delicate touch.

      In another video, a heron seems to be grabbing the bread away from small fish, holding out for a big one at the end:

  6. I have to admit, I’ve never seen this behavior either, though I’ve actually used bread to lure fish towards shore, so that the herons and egrets would stay within decent photo range!

    One thing that has me curious. I’ve seen the white ibis behavior, from the beginning of the video, numerous times. They dunk their bread too, but near as I could tell, it’s to make it more palatable and easier to swallow. The ones visiting the pond where I used to live would run several meters to dunk their bread. I have to wonder if the green herons learn the behavior in areas where they’re close to ibis and can see the result? Or simply in areas where people feed the ibis and ducks and such?

    As for gulping down large catches, I captured a photo sequence of a great blue heron a few years back that impressed the hell out of me. It can be seen here if you’re interested.

    1. Nice photos! I think that the behavior may have arisen either by watching other birds, or by accident, when a bird is softening bread by dunking it in water, and then seeing that fish are attracted. There’s a YouTube video of a crow catching a fish this way, but it appears at first that he’s simply dipping the bread in the water to soften it up, but then sees and catches a large fish trying to nom the morsel.

    2. Wow, wonderful heron sequence Just Al!

      I suspect everyone knows how important it is for the bird to line up the fish just right before swallowing, lest dorsal and/or pectoral spines catch in its throat.

  7. Also, you gotta ask how long have they had bread lying around? Would there have been a natural alternative they could have had use of, like worms? (Are they adapted to find worms? In any event, the worms would sink. From these videos it looks like a successful bait would need to float.) And in times of hardship, humans won’t be so likely to leave bread bits around for them. So there’s been an evolutionarily short period for them to develop this technique.

    In any event, this suggests that Jerry’s late pal Ken Miyata has been reincarnated as a green heron!

      1. Thank you for posting that article. I’ve long enjoyed Tropical Nature and it was nice to fill in some blanks about one of its coauthors. Too bad the pictures are no longer available.

      2. Yes–thank you. That was a beautiful article. Brought tears to my eyes. I remember reading that he’d passed away young in an accident, but didn’t know what had actually happened.

  8. “making the connection between dropping something on the water and seeing the crowd of fish that results and intentionally dropping bait into the water is very difficult.” Really? When an animal does something and it results in food showing up, you can bet they will try it again! That seems very basic and obvious to me. In this same sense though, I know cats which can use “tools.” One cat learned that an excellent way to awaken sleeping humans is to push their waterglass toward the edge of the bedstand. I’m sure other readers can provide similar examples.

  9. That was incredible.

    Damn this is a good website. Thanks for the hard work and dedication to your readers, Professor Coyne. I’m absolutely certain you have more than a few other demands on your time.

  10. We get them in South Africa.

    One of the things that got me into birding was my father feeding some birds (Basically a bunch of masked weavers) and a green-backed heron coming up to get a piece of bread.

    It would then dump the bread in the water to attract minnows.

    1. Hello Bruce,
      I hope that you clicked on the box “Notify me of follow-up comments via email” because I should like know when (month, year) you have made this observation in South Africa and where exactly if possible ?
      I’m a french ornithologist and I’m trying to build a map of observations for this species during last years.
      Thank you for your response. Regards

  11. I have observed green herons hunting frogs beside my small pond. When they spot a frog, and are preparing to pounce, they will sway their heads from side to side, imagine the cobra swaying to the flute, then strike. Never noticed any fishing with bait behavior, but there isnt any bread about either…

  12. Sorry for this late post but, as a long-time fisherman (recreational angler not commercial fisherman), I have deep reservations about calling this bird behavior “bait fishing.” I think the key word is “structure.” One thing I know about fish is that they are attracted to structure (from tiny “bait fish” to larger predatory or “game” fish). This structure can be anything on the surface or underneath: floating kelp paddy, debris or underwater such as rocks, reefs, sea mounts, etc. Fish are attracted to such structure. Many times I have dropped a lure or bait straight down from an anchored or drifting boat and found fish willing to bite.

    That bird standing still on the shoreline also acts as visual structure to fish. The bird dropping a piece of debris in the water adds to the structure and the liklihood that fish will swim toward the structure and fall prey to the bird. Picking up the piece of debris and repositioning it only keeps the fish within striking distance. In no way is this equivalent to casting and retrieving a lure or bait as a fisherman might do. At least, that’s my take on the matter.

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