Naturespeak A naturalist's view of the world

January 28, 2010

Frozen Motion (with a Red Fox thrown in)

Filed under: Uncategorized — wykes @ 6:19 pm

I realize that I frequently bring dead things to your attention quite a bit. Road-kills, hawk-kills, and owl-kills are potentially educational and I feel justified bringing them to your attention based upon the “it’s a shame to waste a dead thing” rule. Raccoons are not subject to this dictum, because they are worth wasting, but all other once-living things are game (or “gamey” as the case may be). At any rate, I try not to overdo it. It is a concerted effort on my part to pepper accounts of living and dead things equally through this blog. I do this also as part of an on-going effort to bring you in-focus pictures. You see, another little appreciated aspect of dead animals is that they tend not to move and are relatively easy to photograph.  They stay in focus.

A perfect case to illustrate the above point happened only yesterday. I almost hit a Red Fox as he dashed in front of me on LaSalle Road. The creature was going like a bat out of hell with his ears pinned behind his head. A large black dog was hot on his tail as the creature dashed across the yard to my right and flew over the width of the road in about .05 seconds. The dog broke off his chase at the roadside – having successfully cleared his master’s domain of vermin. The fox never looked back and melted into the scrub on the other side after a few more gallops.

I stopped to reach for my camera but the event was over so quickly that I failed to get a shot off. If I had, the whole scene would have been a blur anyway– a streaking red-brown blur taken through a dirty windshield. The black dog was beaming with excitement and would have gladly posed for a portrait (no doubt requesting it to be entitled “Blackie – Slayer of Foxes.”) But, I didn’t want a dog shot. If I had hit the fox with my car, on the other hand, things would have been very different. The ensuing photos would have clearly shown Renard’s beautiful orange fur, black feet, and cat-like eyes and I could have waxed poetic on these features.

I am doubly glad at having witnessed the event without hitting the fox, but this means that I have nothing more to say about this matter except: “the quick brown fox jumped over the lazy dog.” I am, instead, stuck with the subject of discussing dead and near-dead tadpoles. I’ve been holding back on this one but feel it’s time.

Earlier in the season a deadly series of weather events combined forces to exact a heavy toll on some over-wintering bullfrog tadpoles. A west wind emptied most of the water out of our local Lake Erie marshes just as the temperatures plummeted. The water froze quickly into a solid block and locked dozens of tadpoles and young fish into a death grip (see here). Many of the tadpoles appear to have been literally frozen in motion – their dead bodies caught in “life like” poses (see above and here). The dead fish, consisting of a large-mouth bass and a few sunfish, looked like glass-eyed frozen fish but they exhibited some nice coloring (see below). My photos in this case are in focus although they will not appear so because the subjects were encased in ice.

My first reaction was that the pollywog kill was complete. It appeared that these unfortunate fellows had paid the price in the monopoly game called life. Under the ice, however, you could still see the slow-moving forms of living tadpoles just beneath the surface. There were individuals still hanging on.

Over the course of the next few weeks, the ice thawed a bit. Meltwater and rising water created a new layer over the older ice cover. The remaining tadpoles were entering into this inter-ice zone from access holes through the older ice (see below). Their movements were highly restricted by the honeycombed environment of ice tunnels and labyrinths and many were getting trapped. Only those that kept moving maintained some kind of an open space around them.

Bullfrogs always take at least one, and sometimes two years or more to complete their metamorphosis. This means over-wintering both as a tadpole and an adult. Most of the adult frogs stay put. They burrow into the bottom mud and hibernate. Thanks to elevated levels of glucose-based anti-freeze in their bodies, both adult and tadpole are immune to low temperatures. This immunity doesn’t extend down to the freezing level. Unlike some northern frogs, they are apparently freeze intolerant. Bullfrog sickles, in other words, will not come to life upon thawing.

The tadpoles maintain an active winter existence as long as there is liquid water available. They may seek out deeper water in the summertime but invariably choose to inhabit shallow areas in the winter. This is probably due to the available sunlight and algae growth found in the shallows. Ice bound water also tends to become low in dissolved oxygen so it is doubly wise to seek open watery edges. Unfortunately, the tactic is a risky one as we can see by this year’s problems.

I’m fairly sure that most of the later ice-trapped tadpoles will survive. They will wiggle their way around until re-gaining access to the lower depths. Like the swift brown fox earlier, enough will survive into the spring in order to carry on their way of life. Those that fail in this endeavor will stay trapped in eternal youth – perfectly focused at one stage of their life.

1 Comment »

  1. I’m glad you posted this. We had a significant loss of bullfrog tadpoles in our pond this year. They appear to have trapped themselves in the ice, and came to the top with the recent thaw. We also lost at least one fish. This was significantly higher than we had expected. We do not know how many tadpoles we had, but we lost around 40. We did spot one still swimming about.

    I’ve seen the frozen fish down in the small boat harbor in the same state you pictured. It can be pretty horrific in places.

    all the best,

    Dave

    Comment by dave — March 17, 2010 @ 11:49 am

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