California Condors, Megafauna, and Trophic Cascades

A long time ago I worked as an archaeologist near Santa Barbara.  I spent most of my days in the field excavating Chumash sites, recording evidence of looting, drawing maps, and hunting for unknown sites.  It was a fun job, I learned a lot, and it was my first exposure to California Condors.

The Chumash left behind a repository of exquisite petroglyphs, painted and carved into the soft sandstone that makes up much of the Transverse Range, an east-west oriented set of coastal Southern California mountains.  One of my jobs was to preserve this rock-art.  In the dust that makes up the floor of the caves and shelters the art is painted lives a bacteria that eats the organic pigments in the paint used by the Chumash.  Visitors would unwittingly kick up the dust, spreading the bacteria and speeding up the degradation of the rock art.  At several sites we paved the floor with stones to trap the dust.  One of these sites was Condor Cave in the San Rafael Wilderness; I’m sure you can guess how it came by that name.

Condor art at Condor Cave – from http://www.parks.ca.gov

It wasn’t until several years later I when was backpacking in the Ventana Wilderness with a friend that I saw my first wild California Condor.  We stopped and sat, mesmerized, watching five large birds swoop and soar around us.  Of course my camera was acting up at the time and the only photos I got were pathetic to say the best.  The experience stuck with me, all the more so because I had been studying anthropology and repercussions of the North American megafauna extinctions.  

About a week ago I was driving from San Francisco to Los Angeles along HWY 1.  It was one of those spectacular California days where the coast is shrouded by pockets of thick fog broken by regions of bright sunlight and the Pacific Ocean lives up to its name lying tranquil in its bed.

Sun, fog, and kelp-beds along the coast between Morro Bay and Big Sur

Sun, fog, and kelp-beds along the coast between Morro Bay and Big Sur

This stretch of road is made up entirely of corners and as I rounded one I saw a pocket of people pulled over in a turn-out looking up at something on the hill-side.   I caught a glimpse of a large bird on the slope, pulled over at the next turn-out, grabbed my camera, and jogged back to find a very calm California Condor sunning itself in the late afternoon light.

California Condor soaking up the last of the sunlight

California Condor (Gymnogyps californianus) soaking up the last of the sunlight

The California Condors are in rough shape.   DDT, hunting by mis-informed ranchers who believe that condors killed calves, egg collecting, habitat loss, and lead-poisoning are all implicated in modern times for the low numbers of  the California Condor (Gymnogyps californianus).   Additionally, these long-lived birds have small clutch sizes (few eggs per breeding cycle) and reproduce extremely slowly; so slowly that a 1996 study by the Fish and Wildlife department found that it would take 1800 years at the current population growth rate of 1.0003 to achieve a stable wild population of 150 individuals.  This low population growth rate is part of why there is a captive breeding program.

California Condor (Gymnogyps californianus) in the Los Padres National Forest

California Condor (Gymnogyps californianus) in the Los Padres National Forest

In historic times the California Condor ranged from British Columbia to Baja, but during the 19th century its range was rapidly diminished to include only California.  Through captive breeding and release strategies the range has been re-expanded and now includes Arizona, northern Mexico, and a little of Utah, in addition to California.  These birds have what is known as a “relict distribution”, that is, they occupy only a fragment of their former range.

California Condor range map - from: IUCN Redlist http://www.iucnredlist.org/

California Condor range map – from: IUCN Redlist http://www.iucnredlist.org/

 

While it is certainly true that lead poisoning, DDT, and all the rest have been massively detrimental to present day condors this overlooks a very important aspect of the condor niche.  These are large birds, the largest flying birds in North America, with up to a 9.5 foot (2.9 me) wingspan and weighing up to 23 pounds (10.4 kg).  These birds are meat eaters and they need a lot of meat.  The historic population was highest along the coast, where aquatic megafauna would, and still does wash up on the beach.  Beached whales, elephant seals, sea lions, dolphins, seals, and large fish may be disturbing to see, but they provide a wealth of food for bears, foxes, coyotes, weasels, wolves, eagles, gulls, ravens, and condors.  It is true that there are still large gatherings of sea mammals along the coast, but it is also true that there are far fewer of them than there used to be and this has imparted an additional stress to the condors, among other species.

Northern Elephant Seals (Mirounga angustirostris) on the California Coast

Northern Elephant Seals (Mirounga angustirostris) on the California Coast

For birds further inland other sources of meat were, and are important.  Terrestrial megafauna is what fed and feeds inland condors.  We have nowhere near the diversity nor the biomass of large free-living terrestrial animals than we did even a few hundred years ago, let alone what we had when humans first arrived in North America.  Shortly after the arrival of humans most of the large animals, the megafauna (generally being defined as an animal with a body-mass greater than 100 pounds (45 kg) began going extinct.  The giant beavers disappeared, the mastodons vanished, the giant sloths, camel relatives, giant tortoises, horses, and various species of deer were wiped from the continent, and along with those animals also went other animals that relied upon them; dire wolves, saber-toothed cats, short-faced bears, American lions, American cheetah, tetratorns (think condors on steroids), dung beetles, and condors.

Tule Elk (Cervus canadensis ssp. nannodes) being restored to California grasslands

Tule Elk (Cervus canadensis ssp. nannodes) being restored to California grasslands

There is vociferous disagreement as to why the megafauna went extinct, but many, if not most, scholars believe that humans hunted these animals to extinction.  Humans arrived during an ice age and the rapid change in climate (rapid in an evolutionary sense) may have placed the animal populations in a position where enthusiastic hunting had a greater impact than would be otherwise expected; but whatever the exact details the short story is that humans arrived and within a few thousand years a majority of the megafauna went extinct.  This triggered what is known as a “trophic cascade”.

You can think of an ecosystem as being analogous to a game of Jenga.  All together the blocks form a solid tower, but as you remove blocks (species) the tower (ecosystem) becomes more and more unstable.  Eventually one too many blocks is removed and the whole structure comes tumbling down.  In essence, this is what a catastrophic trophic cascade looks like.  So many animals were removed from the ecosystem that now, eleven thousand years later, we are still seeing some of the effects.  Just as blocks you never touched in the Jenga game come tumbling down, species of plants, insects, and animals that were never hunted went extinct or had their life patterns radically altered.  Some plants lost their ability to disperse their seeds, forests and grasslands were no-longer grazed as heavily and the composition of species changed drastically, watersheds and rivers changed their patterns, soils changed as they were walked upon by different animals with different behaviors, concentrations of bacteria and fungus changed, altering soil and groundwater chemistry.  Trophic cascades are a big deal.  They are ongoing, but operate in the background, running smoothly and unnoticed until something breaks the chain of events and the whole tower of blocks comes tumbling down.

The current narrow range of Condors is due, in part to the cascading effects of the megafuna extinctions and more recent changes brought by colonizing Europeans.  We know from the fossil record that prior to the megafauna extinctions several species of condors lived in North America over a range that includes the historic range of the California Condor and stretched across the southern states and up the east coast to New York.

Prehistoric US fossil sites for North American condors, courtesy of the San Diego Zoo library

Seeing the California Condors in the wild is like catching a brief glimpse into the distant past, a time when North America had wildlife diversity to rival that of Africa.  The fate of the condors is far from certain.  They are from a time and place that no-longer exists and it remains to be seen if they can adapt to the world as we have made it, even with our assistance.  I hope the condors do succeed, the world is a richer place and better place for their presence.

Preening in the late afternoon sun

Preening in the late afternoon sun

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2 comments on “California Condors, Megafauna, and Trophic Cascades

  1. EDG says:

    A fantastic and informative post!

  2. chris339 says:

    Great post! Love the Jenga analogy.

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