Dicromantispa interrupta

Dicromantispa interrupta

Monday, February 9, 2015

Great Blue Heron Method for Eating Catfish

The camera trap last night produced nothing, a surprise considering that it has videoed wildlife every night since being set out. Perhaps the critters are tired of dried instant rice, or maybe they aren’t interested in tomato peelings and spoiled blueberries. New bait is in order – more banana chips at the very least will be set out tonight.

But the day’s Orange Lake wildlife viewing has started out much better. While on telephone hold, I noticed a Great Blue Heron standing on the bank maybe 50 yards from me, so I put binoculars on it to see why it was not in the marsh. The bird had a 6- or 7-inch brown bullhead (Amieurus nebulosus) in its mouth. While I watched, the heron dropped the fish, turned it over belly up, and used its beak to stab into the head through the fish’s softer chin. Each stab involved the top and bottom bills slightly agape, so that it actually made two wounds with each thrust. This happened repeatedly, with the fish slowly showing less and less life over time.

Ordinarily, we see a heron snag a fish and swallow it right away, but the catfish’s three long spines prevent quick ingestion and the poison gland at the base of each spine is also a deterrent. After 15 or 20 minutes of this, the fish was lifeless and the heron began pecking at the bases of the spines to break them. It returned to the water several times during the procedure to wash off dirt and grass adhering to the fish’s sticky skin. After killing the fish and removing its spines, the heron returned to the lake to wash it one last time and then swallowed it.

Contrast this heron’s method of removing catfish spines to that of a Double-Crested Cormorant I reported on February 22, 2008 at tinyurl.com/lljuy2o.

I figured the heron would loaf for a while to wait for the fish to pass through the gizzard, but no, it went right back out to forage for more prey, catching another little victim or two:

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