Natural and Unnatural History II

I’m traveling in the Galapagos currently.  Hopefully I’m having fun and seeing great birds and other species!  In the meantime here’s a little of what I will hopefully be seeing!

The Galapagos’s Natural and Unnatural History: Climate

Climate is a remarkable thing and it’s effect on the islands is profound.  The Galapagos are a series of islands that straddle the equator.  As such it means that seasons aren’t based on light availability.  There are 12 hours of daylight and 12 hours of night with the sun dawning around six and setting at six in the evening.

Like the tropics we think of when we consider Costa Rica and the Amazon, the seasons are wet and dry.  The climate of the Galapagos is influenced by oceanic currents. The warm/wet season typically runs from January through June (garuas), but is highly variable in its start date.   During the cool/dry season (garua) seas are choppier due to prevailing winds, and while the lowlands experience virtually no precipitation and the highlands are continually receiving rains.  Temperatures typically range from 24 to 28 C (75-82F).

In the heart of the Pacific, the Galapagos are dramatically affected by climatic events of El Nino and La Nina.  Much of what I’ve read regarding climate and the Galapagos was published in the early 90s so the lack of recent data will leave holes in my knowledge and I’ll have to extrapolate a little.

El Nino, is a climatic event that affects the coastal waters off Peru every 3-5 years.  These events can last a few months to nearly two years. El Nino events typically start in December or January when the oceanic currents bringing cold water to the surface along the western coast of South America cease.  Instead water waters blanket the coast.  This has immediate local affects and long-term global influence.  The fishing industry is halted as the warmer waters hold fewer nutrients, so the food webs and fish stocks plummet.  The suspension of the current has ramifications across the planet.   Wet areas such as the Amazon basin receive significant less rainfall, other regions receive increased levels of precipitation

In the Galapagos, an El Nino year promise high levels of precipitation while a La Nina year means virtually no precipitation and cooler temperatures. While La Nina is in essence the opposite of El Nino (water temperatures along Peru’s shores decline), the start time of the phenomena is the same.  La Nina occurs every 3-7 years, frequently, but not always following an El Nino event.

Why the all the discourse on Spanish babies? As I mentioned earlier, Climate is the determining factor of success in the Galapagos.  As mentioned in Natural and Unnatural History I, the wet season is not based on the calendar, but on the initiation of the rains: if there are no rains, then there is no wet season.

Imagine life continuing if the heart stopped beating.  In the Galapagos: that’s precisely what the wet season is: one more throb of the heart.  In the span between beats, each organ holds for the next pulse of oxygen.  In the Galapagos, each species, and each individual waits for the next wave of rains to replenish life.  Life in the Galapagos has evolved to wait until rain starts.  When the rains don’t come, species teeter, like losing balance a top of cliff in suspended time. Hope rails, and individuals doggedly persevere.

During the drought of 1977 the total precipitation fell from an average annual 200 mm (can’t locate accurate precipitation levels for 1977). It was not enough for finches under observation by Peter and Rosemary Grant to breed.  Conducting their research, scientists discovered “dead fortis lying on the lava with feathers so dishelved they looked as if they had been combed the wrong way.”

“We just sat there, month after month.  We were depressed.  We were losing the breeding season, so we wouldn’t get a generation.  Plus, all these birds were disappearing.  We kept up doing the normal checks and censuses.  But our feeling was not the thrill of seeing evolution in action as one might conclude from reading subsequent papers, but the moderate despair of doing a research project and seeing your birds dying.” – Peter Boag, The International Finch Investigation Unit, recollections on 1977

The cactus finch population declined 60% while the fortis population declined 85% during that climatic event.   There’s no foretelling El Nino and La Nina, all you can do is wait and watch and hope.  Each year is the same: breeding begins, life resumes when the rains fall. When the rains finally fell, after one alarming delay, one researcher, “dance[d] in it for two solid hours praising the heavens,  a dervish of tangled hair and beard and ripped clothes, hollering into the rain.”

Contrast that with the strongest El Nino on record (at the time my sources were published): 1982-1983.  “The year before there had been no breeding at all (1981-1982).  Now  they bred like hell.  On Daphne (Island) , females produced up to forty eggs and fledged twenty-five young. The most prolific pair on Genovesa Island lad twenty-nine eggs in seven clutches, and twenty fledglings hopped out of the nest, a record for the island.”

At the time, the El Nino of 1982-1983 was considered the strongest El Nino on record. However, the El Nino of 1997-1998 really brought the phenomena to the forefront of media and is considered stronger than 1982-1983.  There were three additional El Nino periods in the interval.  From my recollections, (I was in high school at the time), 1997-1998 is the first El Nino I was aware of and I seem to recall excessive media coverage
remarking on the extraordinariness of this particular event and bringing to global awareness to climate fluctuations.

So, needless to say, climate is intimately tied to the Galapagos.

Quotes from “Beak of the Finch: A story of evolution in our time”. Jonathan Weiner.  1995.

Sources:

  • “Beak of the Finch: A story of evolution in our time”. Jonathan Weiner.  print. 1995.
  • “Galapagos: a natural history.” Michael. H. Jackson. print. 1993.
Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s