Heron’s Breakfast

This Great Blue Heron chose the inch-deep waters at low tide off the rocks on the northeast corner of the park as its hunting ground this morning. I guess this versatile hunter felt like seafood for breakfast, instead of gopher. It soon nabbed a fish about six or eight inches long. As the video shows, the bird went through elaborate preliminaries. By my count, the bird dipped the fish in water, or dropped it and picked it up again more than two dozen times over two and a half minutes before swallowing its meal. This is typical behavior for the Great Blue, as well as for the Snowy Egret, as filmed here previously, and probably for herons and egrets generally.

Why do the birds do that? The cat and mouse model comes to mind. Domestic cats, according to one authority on feline behavior, seem to play with a captured rodent or bird — repeatedly letting it go and recapturing it — for the utilitarian purpose of tiring the animal out to the point where it can no longer defend itself and injure the cat. Mice have sharp teeth and birds have pointy beaks that could hurt a cat. So, behavior that appears to be cruel play is a purposeful survival tactic on the predator’s part. This model does not translate well to the heron v. fish setting. There is no way that a fish of this size could injure the heron. I’ve looked for studies of this behavior in herons, and the best I’ve found so far is an article from Brazil about cormorants and Green Herons, which suggests that juvenile birds do this with live or dead fish as well as with random floating objects as a form of educational play through which they learn adult skills like hunting and nest building. Feeding was not the primary motive there. Very well, but neither this heron nor the egret I’ve previously filmed spending minutes dipping their captured fish appeared to be juveniles, and the behavior here was definitely a prelude to feeding, not random educational play. Could the bird be making sure that the fish was completely dead before swallowing it? Hard to tell exactly, but this fish seemed to be quite lifeless by about the third or fourth drop and recapture. Why the additional 20 or so repetitions? Was the bird making sure that the fish had expelled all waste material from its cloaca? The repeated dipping might have a washing/cleaning intent. If a reader has more definite information on this topic, please post a comment. Thank you.

Great Blue Heron (Ardea herodias)

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4 thoughts on “Heron’s Breakfast

  • June 28, 2020 at 12:15 pm
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    Regarding my comment on 26 June – 11:37pm, about “(The part of the drawing of the sculpin showing its dorsal fin is hidden. You need to copy the image and paste it into an image viewer.)”, that was fixed. So now the entire drawing of the sculpin’s dorsal / ventral fins is visible. Thanks Marty.

    Peter

  • June 26, 2020 at 11:37 pm
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    At first, I thought it might be the Pacific Staghorn Sculpin also.

    But a closer look at the dorsal and anal fins suggest not.

    I think it is https://en.wikipedia.org/wiki/Porichthys_notatus (Plainfin midshipman).

    See the screenshots from the video of Marty’s fish, plus some illustrations comparing the fins of the two spp. here:
    https://chavezpark.org/what-kind-of-fish-did-the-heron-have-for-breakfast/

    (The part of the drawing of the sculpin showing its dorsal fin is hidden. You need to copy the image and paste it into an image viewer.)

    Peter

  • June 26, 2020 at 6:43 pm
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    amazing that it can swallow that whole! a new take on sushi!

  • June 26, 2020 at 7:03 am
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    Great Video Martin.
    That particular fish is some type of sculpin. The have a defensive system. The gill plates `have very sharp protuberances. One of their defensive techniques is to flare open the gill plates and make it difficult for anything to swallow it. Having used them for bait, the first thing they do when you hold them is to open those plates wide and have the sharp bony structures available for you to stick youself. I suspect the heron is repeatedly releasing it in shallow water and stabbing it with its bill to kill it and make sure there is no movement and make it safe to eat. You could imagine what would happen if it expanded it’s gill mid passage in the heron’s neck. You notice there is no longer any spontaneous movement in the sculpin. Jim

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