Posted by: Rob Viens | October 19, 2013

Mosquitoes and Scissor-Beaks

For the next few days, Darwin floated down the river – leaving his cabin for the occasional fresh fish:

“A constant gale & rain from the SE, remained at our moorings. — the greater part of the time I passed in bed, as the cabin was too low to sit up in. — there was also good sport in fishing, the river abounds in large & extraordinary looking fish, which are excellent food. (Oct 13/14)

Surprising, much like my own experiences on the Stikine River in Alaska (described in the last post), Darwin was plagued by black flies and mosquitoes:

“The evenings are quite tropical; the thermometer 79° —an abundance of fire flies, & the mosquitoes very troublesome. — I exposed my hand for five minutes, it was black with them: I do not think there could have been less than 50, all busy with sucking. — At night, I slept on deck, the greater coolness allowing the head & face to be covered up with comfort.” (Oct 15)

The head of a female mosquito under a scanning electron microscope (SEM) – notice all the sensory organs used for quickly finding prey (from Zwiebel Labs via the magazine Exploration) – Read all about the olfactory system of the mosquito – I have to say it is pretty cool.

mosquito head

For years I have used the exact same description as Darwin to relate the experience of mosquitoes on the Stikine.  We would wear total body cover – including gloves and a head net – to protect ourselves from the clouds of blood-sucking insects.   Like Darwin, I would always tell the story of exposing a hand in the evening, and within a minute, finding  50 mosquitoes jockeying for position on my palm.  The good news – one smack took them all out.  The bad news – 50 more took their place almost instantly.  The most depressing moment of my three years of field work in the region came when I took my off my head net while paddling up the river.  In an instant it slipped into the water and sank into the darkness – and I envisioned those 50+ mosquitoes clustering on my face for the remained of the trip. It was tempting to just let the river wash be out to see (at least there wouldn’t be any mosquitoes).   Fortunately, a heavy dose of DEET kept them away for the remaining time (though I often wonder what the long-term consequences of that solution was J).

Luckily for both of us, these mosquitoes were not bearers of malaria, like those found in warmer climates.  The Beagle voyage had already been plagued by that disease in Brazil – and 3 people died (see “Bad Air” on the Beagle).

As much as I hate mosquitoes, I can’t help but be impressed with their snorkel-like adaptation which allow the larva to live in stagnant, oxygen-poor water.  Since their predators don’t have a similar adaptation, the young “skeeters” can grow to a ripe old age (of about 1 to several weeks old), and form clouds of blood-sucking scientist eaters.

Mosquito larva breathing air (from Wikipedia Commons)

mosquito larva

During the day, Darwin did some paddling up the side channels on the river (another parallel memory I have from the Stikine).  Here his attention was drawn to a very unusual bird:

“We got under weigh; passed Punta Gorda, where there is colony of tame Indians from the province of Missiones. — We sailed rapidly down the current; before sunset from a silly fear of bad weather brought to in a narrow arm or “Riacho”. — I took the boat & rowed some distance up the creek; it was very narrow, winding & deep; on each side there was a wall 30 or 40 feet high formed by the trees entwined with creepers, this gave to the canal a singularly gloomy appearance. — I here saw a very extraordinary bird, the scissor-beak. — the lower mandible is as flat & elastic as an ivory paper-cutter, it is an inch & a half longer than the upper. — With its mouth wide open, & the lower mandible immersed some depth in the water, it flies rapidly up & down the stream. Thus ploughing the surface, it occassionally seizes a small fish.” (Oct 15)

Darwin’s “scissor beak” – a black skimmer (from Wikipedia Commons)

scissor beak

Darwin was fascinated by the “scissor beak” and spent a lot of time describing it in Voyage of the Beagle, too.  For details on that description (and more on the scissor beak from his observations of the bird in Maldonado) and a video of these fascinating birds, see Fishing with Rynchops).

More on Darwin’s “float trip” in the coming days…and then it is back to Buenos Aires… (RJV)

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