Naturespeak A naturalist's view of the world

March 6, 2009

Herons on Ice

Filed under: Uncategorized — wykes @ 12:16 pm

A show called “Herons on Ice” would never compete with the likes of something like  “Sesame Street on Ice.”  Herons, when on the ice, do a whole lot of nothing.  Any show featuring them would have the excitement level of watching a silent group of human ice fishermen. Unfortunately, these gangly birds are also prone to stage fright and will flee whenever an audience is detected. No, this production can only be designed for the parameters of your small computer screen. Watch this short clip here and you’ll witness one of these rare “Herons on Ice” performances. The sequence was filmed without their consent, but I’m sure the Herottorneys will understand (and I’ll pledge to be careful from heron in).

It was a very windy (and very cold) day when I happened upon the gang of avian fishermen working an icy section of a Lake Erie Bay. This is the excuse I’ll put forward for the very shaky camerawork – some of the gusts nearly knocked me off my feet. The out-of focus stuff, well, that was the camera’s fault and besides the sun wasn’t out and…. never mind. Anyway, deteriorating ice conditions created a shelf over the shallow bay pockmarked with several large access holes. The herons, accompanied by dozens of very active and noisy Ring-billed and Herring gulls, had claimed solitary positions over each of the holes and were engaged in ice-fishing.

Apparently, the ice holes were attracting schools of emerald and spot-tail shiners. All the herons had to do was wait them out and pick them off one by one as they approached the hole. Herons are endowed with the kind of incredible patience that is required of any ice fisherman. This technique fits them well. A normal feeding sequence begins with a prolonged motionless stare, a sudden cocking of the neck (see below) as the target is sighted, a darting grab, and then a satisfied swallow. The herons expand their throat when swallowing and this gives them a fleeting bull neck look (see here).

It wasn’t uncommon for a bird to come up with a clump of water plants along with their chosen prey. When this happened (as it did at the end of the video clip) the herons were able to demonstrate their amazing bill dexterity by simultaneously flipping the offending piece out while directing the tiny fish in.  I watched them do this several times and never saw them drop a single fish. I know the gulls were watching them too, but they did so in vain.

The gulls were mostly haggling and fishing among themselves and leaving their long necked cousins alone. The fact that a Great-Blue Heron stands four feet tall, wights 6-8 lbs., and is equipped with a spring loaded dagger probably accounts for the gull’s un-gullike show of respect.  One feature that really stands out when a large bird like the Great Blue is completely exposed out on the ice is the subtle palette of grays, purples, blacks, and chestnut exhibited in the plumage. The long filiform feathers coming off the top of the head acted as jaunty weather vanes.

About the only thing left to discuss about this situation regards how many minnows a single heron eat. In the 15 minutes I watched these birds, I’d say that each individual took in about 4 or 5 fish. As opportunists, they will eat until the cows come home because they know that those cows don’t always come home in the wintertime. Statistically, the average intake for a healthy Great Blue is about 300 grams of fish flesh per day. This figure was calculated based on warm weather consumption, however, so it is likely that the bird’s cold weather needs are far higher.

I did a little figuring, and assuming that the shiners were spot-tails or emeralds, they would weigh an average of only 15 grams a piece. This means that a self-respecting heron would need to haul in about 25 or 30 of them to make a day of it. Watching these herons perform, I have little doubt their show was well on its way to being a success.

1 Comment »

  1. I can’t wait for the great blue and green herons to return to the pond behind our house..They are amazing fisherman..along with the belted kingfishers that visit also…

    Comment by ramblingwoods — March 19, 2009 @ 11:42 pm

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