American Journal of Life Sciences
2014; 2(1): 5-23
Published online January 30, 2014 (http://www.scien
cepublishinggroup.com/j/ajls)
doi: 10.11648/j.ajls.20140201.12
The horse and burro as positively contributing retu
rned
natives in North America
Craig C. Downer
Andean Tapir Fund, P.O. Box 456, Minden, NV 89423-0
456 USA
Email address:
ccdowner@aol.com
To cite this article:
Craig C. Downer. The Horse and Burro as Positively
Contributing Returned Natives in North America.
American Journal of Life
Sciences
. Vol. 2, No. 1, 2014, pp. 5-23. doi: 10.11648/j.aj
ls.20140201.12
Abstract:
Since the Wild Free-Roaming Horses and Burros Act o
f 1971, debate has raged over whether horses and
burros are restored North American natives. Fossil,
genetic and archeological evidence supports these
species as native.
Also, objective evaluations of their respective eco
logical niches and the mutual symbioses of post-gas
tric digesting, semi-
nomadic equids support wild horses and burros as re
storers of certain extensive North American ecosyst
ems. A Reserve
Design strategy is proposed to establish naturally
self-stabilizing equine populations that are allowe
d to harmoniously adapt
over generations within their bounded and complete
habitats. These populations should meet rigid stand
ards for viability
based on IUCN SSC assessments (2,500 individuals).
Basic requirements are described for successful Res
erve Design
including viable habitat as well as specific region
s of North America where this could be implemented.
Keywords:
Equidae, Wild Horses and Wild Burros, Horse and Bur
ro Evolution, Horse and Burro Ecology,
North American Native Fauna and Ecosystems, Reserve
Design,
Wild Free-Roaming Horses and Burros Act of 1971
1. Introduction
All branches of the horse family (Equidae) share an
ancient evolutionary origin and long-standing durat
ion in
North America, having evolved here for ca. 60-milli
on
years ago. Few other mammalian families can lay as
much
claim to native status and belonging on this contin
ent. Two
other extant families in the Order Perissodactyla a
re the
tapir and the rhinoceros families, and both are sim
ilarly
rooted in North America. From George Gaylord Simpso
n
[1]
to Bruce MacFadden
[2]
, various scientists have described
the horse family’s fascinating story; and their wor
ks reveal
the ascent of many distinctive yet interwoven equin
e genera
and species over the eons. The horse family has bra
nched
out to all continents except Australia (prior to th
e arrival of
whites) and Antarctica. These animals have contribu
ted
positively to our planetary communities, and they c
ontinue
to do so in many ways and on many levels today.
The rapid reoccupation of vacant niches in North
America by the horses (
Equus caballus)
and burros (
Equus
asinus
) may be viewed as corroborating their return to
ancestral grounds. In the words of the Plains India
ns: ‘The
grass remembers the horses.’
In this article, I present evidence for the origin
and long-
standing evolution of both horse and burro evolutio
nary
branches in North America, and further support the
entire
horse family as primarily native here. I go on to s
how that
both horses and burros are returned native species
and
merit protection. In complementary fashion, I also
describe
the unique ecological roles filled by horses and bu
rros,
explaining how they both preserve and restore nativ
e
ecosystems in the American West. Finally, I propose
reserve design
as a means by which wild horses and burros
can restore themselves as vital components of viabl
e
ecosystems and be truly protected as mandated by th
e Wild
Free-Roaming Horses and Burros Act of 1971. I also
suggest regions where this could be possible.
2. Methods
I gathered information for this article through a t
horough
literature review of the history, evolution, ecolog
y, and
conservation of wild horses and burros in North Ame
rica.
This review has been a life-long one and accompanie
d by
visits to and observations of many of the wild hors
e and
burro herds and occupied habitats throughout the we
stern
United States. This has resulted in a graduate pape
r on the
behavior and ecology of the Pine Nut Range wild hor
se herd
6 Craig C. Downer: The Horse and Burro as Positivel
y Contributing Returned Natives in North America
of western Nevada and other reports and publication
s. The
sources for this article are listed in the referenc
es section.
I have attended several professional conferences
concerning wild horses and burros and other wildlif
e at
which I have presented papers, e.g. International
Interdisciplinary Environmental Conference 2013,
International Equine Conference 2011 and 2012, Wild
Horse Summit 2008, and Wild Horse Forum 1980. Mater
ial
from these papers has been incorporated into this a
rticle.
Professional consultation with professors, biologis
ts, and
government officials has also guided the preparatio
n of the
article. Many of the points presented here were als
o
presented in my book
The Wild Horse Conspiracy
.
[3]
My
extensive research on wild equids and other perisso
dactyls
has resulted in scientific publications, including
encyclopedic articles (e.g. Grzimek’s, 2004), a spe
cies
resume and action plan
[4]
, and scientific journal articles, as
well as many popular reports and articles. These ha
ve
described the evolution, ecology, and conservation
history
and plans – past, present, and future – of perissod
actyla
species, including the endangered mountain tapir as
well as
the wild horses and burros of North America.
Characteristics common to the order include a mesax
onic
weight-bearing, odd-toed anatomy, possession of bot
h
upper and lower incisors permitting careful pruning
of
vegetation, and the possession of a post-gastric (i
n contrast
to a pre-gastric, multi-stomach ruminant) digestive
system.
These and other shared characteristics place member
s of
the horse, tapir, and rhinoceros families into simi
lar
ecological niches and roles. A knowledge of these
characteristics affords insight concerning contribu
tions to
the North American ecosystems by both horse and bur
ro
lineages evolving here since the early Cenozoic Era
ca. 60
MYA. This knowledge relates a wider variety of spec
ies,
genera and families that share near-lying branches
on the
“family tree” of life expanding over time. And this
knowledge has greatly aided me in composing this pa
per.
3. Findings and Discussion
3.1. Evidence of the Long-Term Presence and Evoluti
on
of Horses and Burros in North America
3.1.1. Yukon Horse substantiates North American Ori
gin
of Modern Horse
During the mid-1990s, horse remains were discovered
by
placer miners in the Yukon. They were well preserve
d in
the permafrost and seemed to have died recently, ye
t
proved to be approximately twenty-five thousand yea
rs old.
Their rufous color, flaxen mane and solid hooves ha
d the
aspect of a typical, small and wiry mustang of the
West.
Based on external morphology, the specimen was iden
tified
as a “Yukon horse,” whose Latin name is
Equus lambei.
Intrigued, paleontologists conducted a genetic anal
ysis of
this specimen, which showed it to be one and the sa
me as
the modern horse:
Equus caballus.
Further independent
analysis conclusively proved this. With this substa
ntiation
came a more widespread recognition of wild horses a
s
returned native species in North America, since
E. lambei
was seen to be identical to
E. caballus.
[5]
Carbon-14 datings of mitochondrial DNA (passed alon
g
the maternal line) have been meticulously analyzed
by Dr.
Ann Forsten
[6]
and have substantiated the origin of the
modern horse in North America at 1.7 MYA (million y
ears
ago). According to Forsten: “[t]he early branching-
off time
indicated by
mtDNA
supports an origin of the caballoids
[the horse branch of the horse family: Equidae] in
the New
World, and the fossil record suggests an even rathe
r late
dispersal to [the] Old World.”
[5]
The fact that the Yukon horse is genetically identi
cal with
the modern horse reveals the latter to be one of th
e most
deeply rooted and justifiable native species in Nor
th America.
This native status is additionally substantiated by
the species’
large geographic distribution upon this continent t
hat is
evident from the fossil record and the great variet
y of
ecosystems in which it can adapt and live. Furtherm
ore,
though the modern horse traces back ca. 2 million y
ears in its
present form, it should actually be regarded as par
t of the
continuous context of equid evolution that dates ba
ck at least
58 million years in North America.
[7]
3.1.2 More Recent Horses in North America
A considerable body of evidence has surfaced
concerning the more recent survival of the horse sp
ecies in
North America. Though the prevailing view maintains
that
the entire horse family died out around 10,000 year
s ago at
the end of Earth’s last major glaciation, evidence
for horse
presence from anywhere from a little over 7,000 yea
rs
before present (YBP) to less than 1,000 YBP is too
substantial to dismiss.
[8]
Among other lines of evidence,
this comes in the form of fossil bones that have be
en age-
dated to more recent times, horse geoglyphs (ground
drawings) dated to about 1,000 years ago,
[9]
and
petroglyphs, or stone depictions.
The
FaunMap
produced and published by the Illinois
State Museum of Springfield, revealed a number of h
orse
fossil datings within the post-Pleistocene-Pre-Colu
mbian
period that occurred well after the time at which a
ll
members of the horse family are commonly believed t
o
have disappeared from North America. Some of these
are
quite close to Columbus’ discovery of America in 14
92.
[10]
(See section 3.2.)
3.1.3. Petroglyphs and Geoglyphs
During the summer of 2002, I visited the austere Wh
ite
Mountains east of the towering, snow-capped Sierra
Nevada
near Bishop, California. The ancient White Mountain
s rise to
over 13,000 feet at Boundary Peak and contain one o
f the
most ancient life forms on Earth: the majestic, die
-hard
Bristlecone Pine, one of which has been dated to ne
ar 9,000
years of age.
[11]
Intrigued by this atmospheric region on the
edge of eastern California and western Nevada, I we
nt on to
explore the desert valley just to the west of these
mountains.
Here I came upon some fascinating petroglyphs datin
g from
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