By Jeff Goessling
A walk across a longleaf pine-sand ridge is unlike any you
will ever take. The serendipitous geological history of the southeastern US
coastal plain, the only place where this ecosystem exists, makes this ecosystem
seem as if it could have only been created out of biogeographic fantasy. This
ecosystem is among the most uniquely diverse ecosystems on earth. To understand
the present state of this landscape, one must give a nod to both the ancient, geologic
past and the more recent, anthropogenic history of this ecosystem. I will begin
with the latter and end with the former.
When I think of the history of one of the iconic species of
longleaf pine-sand ridges, the gopher tortoise, I am drawn to a past generation
of biologists. And I can’t help but be drawn to the so excellent descriptions
of Archie Carr (more
on Archie Carr) and his pioneering adventures across the remote beaches of
Central America in search of satisfying an insatiable appetite for an
understanding of migratory sea turtles. While Dr. Carr was certainly a die-hard
conservationist, in reading his accounts of his first adventures, it becomes
clear that he was initially interested in determining how many sea turtles
could be harvested for human consumption without driving populations extinct (termed
the “sustainable yield”). However, as Dr. Carr learned more about the natural pressures
affecting sea turtle populations, he came to realize that in fact there was
virtually no sustainable harvest for sea turtles. Any loss of reproductive
females above what they naturally experience would eventually lead to
population declines.
But what was it about a large turtle that made it so
appealing as a human food source (taste not withstanding)? I believe there are
numerous qualities that make us perceive these long-lived beasts as ideal food
sources. Given the right conditions (such as an arribada),
sea turtles once appeared as an endlessly-abundant, easily-accessed, and
substantially-proportioned protein source for a people in need of just such a
food source. Humor me a seemingly parallel situation: from a northwestern river
teaming with large salmon, to a southeastern slough boiling with catfish, we
easily perceive local abundance of wildlife, by itself, as an indication of
sustainability. However, the devil is in the details. What made sea turtles
different for Carr was not the local abundance, nor the cultural perception of
sustainability, but the nature of the very sea turtles that were being
harvested. Specifically, in harvesting sea turtles on a beach, the most
important demographic group was being removed from the populations: mature
reproductive females. Through further research, it has been well established
that any significant increase in adult female mortality tends to drive
populations of these species to decline.
Now imagine yourself on a sand ridge in south Alabama; the
year is 1920 (if you have never been to this region, I will attempt to paint
you a picture). Your paternal granddaddy was native to the area, the son of a
cotton sharecropper. Your maternal grandpa transplanted his family to the area
from Kentucky back when times were good and the seemingly never-ending stands
of virgin longleaf pine were keeping every man and mule in the county busy
building America. The cities are now roaring, and the country folk are
surviving. As you stand on this sand ridge, you look across the open, sunny
landscape. You may hear the far off mobbing of red-headed woodpeckers, or a fox
squirrel overhead cutting pine cones. Consider the diversity of forms around
you. The occasional eastern diamondback, or even indigo snake; the flatwoods
salamander, or the gopher frog that you see every year or so during winter and
spring rains; the abundant warblers that pass through in the spring and fall,
or the cluster of red-cockaded woodpeckers in that old longleaf by the house; there
is a cornucopia of species here, more numerous than seemingly possible. And
while you would not encounter every organism on every day, the source of
stability, the one you know that will always be there is the gopher tortoise.
You know that no matter the weather, the day, or the time of year, if you come
to this sand ridge and look out, you will see the beacon of bright and glowing
sand scattered in front of the deep and wide burrows. And it’s not just one or
two, but many; dozens if not more scattered at a regular, yet random distance. On
this ridge, it would be difficult to walk fifty yards without tripping into the
next burrow. And more than just holes in the ground, you know most of these
burrows have a lumbering resident. You can tell this because of the foot prints
and the shell slide marks in the loose sand. Like the Bachman’s sparrow
cramming a grasshopper down the throat of her young in the nest, you have mouths
to feed at home. You gaze at this landscape, densely stacked with a large,
easily accessed meat source.
While economic booms are happening in the city,
these booms will be relatively short-lived. In a few short years, President
Hoover will be promising a “chicken in every pot” as the effects of the Great
Depression grab hold of the nation. You, however, won’t need Hoover’s chicken,
as you look across this sand ridge stacked with tortoise burrows…
And so it was that tortoises became not only a common food
source, but a staple for many communities across the southeastern US. As I have
been working across south Alabama sampling gopher tortoises, most conversations
regarding tortoises with locals begin with descriptions of bygone times when
everyone in the county was surviving by consuming tortoises. I have heard how
you listen in the hole, how you look in the hole, how you pry a grapevine with
a wire bracket down the hole, how you shoot the diamondback in the hole, and
you can even plow the hole, and it just comes back. From the most effective
method of getting the gopher out of the hole, to how it was butchered, and the
taste of the seven types of meat in a gopher, I am pretty sure I have been told
every gopher tortoise story in the state, with every bit of local flare added. But
what were the negative consequences of consuming this seemingly never-ending
resource? That resource began to disappear.
Significant gopher tortoise declines have been well
documented across the species range (click here for
more). While many reasons for gopher tortoise declines seem an unfortunate
inevitability of urban sprawl, human predation was certainly a major factor in
population declines across the northern Gulf Coast. While the practice of
gopher pullin’ has generally come to a stop (either through legal actions, or
the simple fact that it is less vogue now to eat a large turtle), I would be
reluctant to say that every tortoise walking down the road is assured safe
passage from the gravy pan.
Call them what you want, Hoover chicken, gopher tortoise, or
just plain old gopher, I think it is nearly impossible to overstate the role
this species had in shaping the human landscape of this region over the past
centuries. It would certainly be even more difficult to overstate the
importance of this species in shaping the natural landscape of this region over
the past millennia. And thus, it is out of passion and interest in the
conservation of this species, and the community of organisms which depends on
it, that I have focused my attention.
Humor another step back in time to thousands of years ago.
Thousands of years before humans had colonized the new world. The southeastern
United States looked very different than it does today. With the natural cycle
of climatic warming and cooling, so too, the Gulf of Mexico itself had ebbed to
a smaller version of its current state. In this reduced state, the Gulf of
Mexico has left a ring of desertified, sandy habitat in its wake; desertified,
sandy habitats perfect for a sand-specializing animal to colonize. And not just
one animal but many. And not just animals, but plants too. In the unlikely
bonds of natural selection, a highly unique ecological community was formed
across this landscape. It is formed of species from the desert southwest moving
east to exploit a desert system, and it has members (especially flora) from the
central Great Plains that do well in open savannah habitats. But c’est la vie, sometimes Ma’ Nature just
can’t leave well enough alone. And in a natural cycle of glacial contraction
and expansion, the climate warms, glaciers recede and the Gulf of Mexico rises.
The ecological bonds of this desert system are threatened as the vast,
expansive southern deserts become highly restricted and bounded by an expanded
Gulf of Mexico.
But all was not lost. Where the stability among these
ecological relationships remained was on the ancient sand dunes and ridges of
the coastal south, where in spite of even more moisture, the soils remained
xeric and the habitat remained open. But, this habitat did not remain open
simply by chance; as the climate of this region became warmer, and more humid,
one would expect this region to have become thick and overgrown as a
sub-tropical forest. Enter the longleaf pine- an intrepid species that, despite
the climate, maintained the ancient openness of this habitat through
facilitating regular fires across the landscape. Not only does this tree
facilitate fire, but it thrives in a fire-adapted landscape. Thus, in a state
of positive feedback, the species that maintains the openness benefits from the
openness. And through this interaction, the ancient community of species remains
in this seemingly artificially open, desert ecosystem on the lush Gulf Coast.
And so the longleaf pine ecosystem continued functioning as a unit of interdependent
species.
So what of tortoises? During the ancient colonization of the
vast sandy and well-drained habitats, many species that moved east needed
refuges from the weather (the expansive sands of the southeast did not provide
the degree of habitat structure as did the rugged boulders of the western
deserts). Thus, during periods of extreme or inclement weather, including fires,
many of the vertebrate and invertebrate organisms began to depend on gopher
tortoises for the deep, stable burrows they provided on the landscape. Through
their shared evolutionary histories on this landscape, many of the ecological
bonds between Gopher Tortoises and their co-evolved companions become
inseparable. And many of these relationships remain in this ecosystem. From the
Tortoise Burrow Dance Fly (yes, that is the actual common name) to the Eastern Indigo
Snake, the community of species that directly depends on gopher tortoises is
astonishing.
Having considered the respect for this community that I, and
so many others, hold deeply, I am left to conclude this part of the post by
reflecting on the value of species in our landscape. Inherent value. Not from
the perspective of ecological services that species may perform for the benefit
of humanity, but simply for the value that their mere existence holds. In debates
of ethical perspectives rooted in classical or romantic arguments, I am left
without a solid answer. However, to take the approach of Richard Leakey in
describing the intrinsic value he perceives in elephants (in The Sixth Extinction), there is
something ethically obliging us to conserve gopher tortoises, and so doing,
many other species. For individual gopher tortoises likely outlive most humans;
for they epitomize stability in dynamic equilibrium; for they embody so much of
our recent and ancient past.
The future for this species, and of this blog post, will
rest in how we deliver this message to our society at large to affect positive
change.
Part II and III will appear on
Tuesday and Wednesday.
About the Author: Born in the Bluegrass state, I spent my childhood catching turtles, frogs, and snakes in any Kentucky creek I could find them. From a very young age, my parents were nourishing of my outdoor interests catching and encountering animals in the wild. I believe this is one of the greatest gifts a parent can give a child. I attended Thomas More College, a small liberal arts college in Northern Kentucky, where I was first exposed to biodiversity and conservation as a science. After Thomas More, I earned a Master’s degree at Sam Houston State University, where I studied ecological relationships between invasive boas and endemic rattlesnakes on Aruba. I earned PhD at Auburn University studying how the environment affects immunity in gopher tortoises. I am currently a post-doctoral fellow at Auburn University. I will start as an assistant professor of biology at Eckerd College in the spring of 2018.
My research interests are physiological ecology and conservation biology of reptiles and amphibians. Over the past couple of years, I have had the opportunity to expand a long term mark-recapture dataset of gopher tortoises in south Alabama. This has been more rewarding than I could have ever envisioned. I hope you enjoy reading about my time in the field and perspective on conservation.
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