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May
07
    
Posted (crates) in biology, Ecology, Evolution, nature on May-7-2012

    Central America is the site of contending crustal plates–notably the Cocos Plate in the Pacific Ocean which is being subducted beneath the Caribbean Plate right off the western coast of central america at a rate of 72-81 mm/yr.  It’s this area where the Central America Volcanic Arc exists which forms the volcanoes of Guatemala, El Salvador, Nicaragua, and Costa Rica.  To the north there is the North America Plate which is moving to the west at about 20 mm per year resultng in further seismic turmoil.  Then to the east the North American plates dives beneath the Caribbean plate as does the South American plate to the south.

     Once the link between North and South America was established there was a great influx of North American fauna into South America and vice versa to  a lesser extent.  The great marsupial fauna of South America died off mostly as did other less successful groups.  Some of the South American biota moved into North America.  Central America remains today one of the most biologically diverse areas in the world.

    Costa Rica and the rest of the isthmus has acted as a filter bridge in this great migratory process that really picked up steam only three million years ago when the connection was complete between North and South America.  The diverse topography of Costa Rica has resulted in refugia where species could still live after dying out in other areas.  This combined with the species from the north and from the south has resulted in a tremendous amount of biotic diversity in this small area.

    It is estimated that in this small country there are 500,000 to 1,000,000 species of plants and animals with most remaining unknown.  Insects by themselves make up about half of this diversity, whereas 850 species of birds can be found–about ten percent of all known species of birds.  North America has about half that number.  Others estimate about 160 species of amphibians, 220 species of reptiles and about 10% of all known butterflies.

   And all this in the second smallest Central American Nation (El Salvador is the smallest).  Only 119 km across at the narrowest point in the south and 280 km wide at its broadest point, it is quite easy to drive across the country in about five hours.  Solely in the tropical latitudes it still exhibits a broad range of distinct climate zones (12). 

The eastern Caribbean side is the wetest whereas the western pacific slopes are the driest.  Most areas have a rainy season, or “green season,”  (May-November) and a dry season (December-April) with the rainfall almost everywhere following a predictable schedule.  Usually the highland ridges are wet with the windward sides being the wettest.



 
May
06
    
Posted (crates) in Amphibians, biology, Caudata (Order) Salamanders, Evolution, nature on May-6-2012

It was 3 am and my bleary eyes found it  hard to see through the beating of my windshield wipers, but the tiny object in my headlights appeared to be something other than a small twig.  As I got out of the car and picked it up, I realized it was a salamander quite different than the typical Rough Skin Newt (Taricha granulosa) that I usually found in this area.Ensatina eschscholtzii

Although I handled it with great care, when I placed it into a container to hold it until the next day, I found that in its exertions to escape, it had lost its tail which was squirming distractedly about.  It also appeared quite motionless, and I wondered whether it was dead or whether it was simply feigning death.  After handling it, I noticed a dried secretion on my hand which I was careful to wash off since such secretions can often be irritating to mucous membranes.

    The next morning I found it to be quite chipper despite its moribund state the night before, and I confirmed that it was the lungless salamander, Ensatina eschscholtzii, which occurs from British Columbia to Baja California, Mexico.  This was the second specimen that I found crossing the same street in two months (April and May, 2012)–both times in a light rain around 3 am.

    These little salamanders have no larval stage and lay their eggs mostly in April and May under logs, and bark, and inside animal burrows, etc. and are usually attended by the female.  The clutch size ranges most commonly from 9-16 with a range of about 3-25 eggs.  The time it takes for the eggs to hatch varies amongst the subspecies, ranging from 113-142 days with a maximum of 177 days (Monterrey salamander).  The time involved was usually inversely proportional to egg size.

    The young reach maturity in three to four years with males reaching sexual maturity at about 48-55 mm snout/vent length while females reach maurity when they are over 60 mm snout/vent length.  One researcher (Stebbins) estimated that the oldest animals he studied was greater 8.5 years old while another researcher estimated ages up to 15 years.

Although quite variable in its coloration, it typically has nasolabial grooves, about 12-13 coastal grooves along its side, a constricted tail which can often snap off to distract predators, and light coloration at the base of its legs.



 
May
04
    
Posted (crates) in Personal Stuff on May-4-2012

My 1975 Ford Van that I bought new so long ago.

Recently I said farewell to a dear old friend, my 1975 Ford Van that I bought new back in August, 1975.  I bought it in Eugene, Oregon after getting a teaching job in Baltimore, MD, because I needed something larger than my ’64 VW bug to carry my possessions in.  I drove it to Texas via the Grand Canyon and then to Maryland across the deep south and spent a while in the outskirts of Baltimore, before returning to Texas and then back to Oregon.  After a while in Oregon I drove it back to Texas where I spent a few years before driving it to the Puget Sound area where I drove it almost every day for the next 25 years.  I never spent a night in a hotel during all the traveling, but spent many nights in the bed that I had built in the back of the van.

Over the years I was amazed at the reliability of this old Ford truck despite my lack of upkeep.  If I remembered I would change the oil once a year, but otherwise did little maintenance.  Despite this abuse I drove it as my only source of transportation until 2004 and 350,000 miles later when I bought another car (a Ford Escape which drives like a dream).  I experienced very few problems with the truck and developed a warm affection for it over the years.

AAfter getting the new car I would alternate driving it with the van every few days. After almost a year of this, I found myself driving the new car more and more and the truck less and less.  I would makesure that I would go out and start the truck up occasionally just to keep the battery charged.  Finally I went too long once, and found that the old truck wouldn’t start.  This was back in 2005.  I then let the truck sit beside the house ever since.  Over the years, the old friend gradually began to return to the elements from which it came.  The driver’s side had rusted out, and a little Bewick’s Wren built a nest in the gaping hole.  Thick growths of moss covered the truck and a licorice fern germinated and began to grow from a crack.

The top vent leaked and over the years mold and spider webs covered the interior, although the metal along the inner walls still looked bright and new.  The bed collapsed and the interior paneling sagged and gave way.  The door locks would barely work and the ignition froze up.  It was a prime illustration of the old saying “Use it or Lose It.”

I knew that I would never drive it again, but I kept putting off the inevitable, hating the thought of having it hauled off and out of my life forever.  Finally, my son told me that he knew somebody who would haul it away and pay $280 f.or it.  Here are some of the last views that I had of my old buddy.  I am also enclosing below a photo of my new friend who I hope will be as faithful as the last.  No, it isn’t a Ford!  I am crossing my fingers.