Interesting articles hard to classification
What was the Last Bear to go Extinct? And what does that have to
do with Present-day Conservation?
Dave Garshelis
Co-chair Bear Specialist Group
Minnesota Department of Natural Resources
Grand Rapids, MN 55744, USA
Email: dave.garshelis@state.mn.us
Much has been written about the massive extinction of large mammals during the late Pleistocene. In North and South
America, 72% and 83% (respectively) of large mammal genera became extinct during this period (Barnosky et al. 2004),
which ended 11,700 years ago. A number of bear species perished, including at least 8 species of Tremarctine bears in North
and South America (Soibelzon et al. 2005), 3 putative species of Ursine cave bears in Europe and Asia (Knapp et al. 2009),
plus some other Ursine bears in Asia whose taxonomy and fossil history are still unsettled. The contrast between bear
extinction — and previous diversity — in the Americas, versus Europe and Asia, is dramatic. The mass American extinction
is generally attributed to the arrival of humans combined with effects of climate change, although the relative contribution
of these two co-occurring events is still vigorously debated (Haynes 2009). Is there any lesson here for present-day bear
conservation?
Today’s threats to bears have more to do with alterations of habitat, conflicts over anthropogenic foods, and commercial
exploitation of bears and bear parts. Our human-dominated world of today is certainly quite different than the sparse
human populations of the Pleistocene, which may have killed bears mainly in self-defense.
Larger, more threatening bear
species, with lower reproductive rates, were probably most vulnerable to extinction from overkill by humans. Moreover,
those species of bears that relied heavily on caves directly competed with our cave-dwelling ancestors.
One other, often neglected factor that might have pushed some bears over the brink was competition among the bears
themselves.The last species of bear to go extinct seems to have been the Florida cave bear (Tremarctos floridanus; sometimes called
the North American spectacled bear)1. This is a tentative statement, based on remains of this species dated to about 8,000
years ago, found in a flooded cave (subterranean river exposed at the top) in Florida (Kurtén and Anderson 1980). The
cave, called “Devil’s Den” is now a tourist attraction for scuba divers. The cave was once a sink hole that trapped a number
of species, including what appears to be the last known Florida cave bear. The importance of this find is that it indicates
persistence of this species for nearly 4,000 years beyond the Pleistocene. It is also only about 1,000 years older than the old-
est known T. ornatus, the extant Andean (spectacled) bear of South America, which has no ancestor among South American
bears (Stucchi et al. 2009). These two species are the only members of this genus.
The Florida cave bear derives its name from being found in a number of caves, especially in Florida. However, the species
once ranged as far north and west as Idaho and California, and as far south as Belize in Central America. The species was
quite a bit larger than today’s Andean bear: adult male floridanus may have weighed as much as 300 kg. They were believed
to be mainly herbivorous (Figueirido and Soibelzon 2010); like Andean bears, they may have preyed on some ungulates, but
were likely not a direct threat to people.
The range of T. floridanus collapsed through time, and by the late Pleistocene they remained mainly in the warmer climes
of the southeastern U.S. In Florida, as well as some other states in this region, T. floridanus appeared to be more common
than American black bears. One theory holds that changing climate caused these two species to compete more than they
had previously, eventually leading to the extinction of the larger one (Sanders 2002).
Interspecific competition appeared to constrain the niches of other formerly sympatric bears. During the Pleistocene in
Europe, two species of cave bears coexisted with brown bears; the brown bear and cave bear diets were somewhat different
(brown bears being more carnivorous), but brown bears became more like cave bears after the latter became extinct (Boche-
rens et al. 2011, Münzel et al. 2011). Less well known (because it was rarer), the Asiatic black bear also coexisted with brown
bears and cave bears during the Pleistocene over a broad area spanning from Western Europe to the Russian Urals and Cau-
casus (Baryshnikov 2010). It is unknown why this highly-adaptable species was extirpated from nearly half its former range.
In today’s world, there are remarkably few places where multiple bear species overlap. In North America, brown bears
coexist with American black bears and slightly overlap the range of polar bears. In Asia, Asiatic black bears overlap brown
bears in the Russian Far East, and small portions of western China and northern India; they also overlap giant pandas in
central China, sun bears in Southeast Asia, and sloth bears in northern and eastern India. Little is known about competi-
tion among bears and its potential ramifications for conservation. Mattson et al. (2005) posited potential negative effects
of American black bears on grizzly bear recovery in western U.S. via exploitation competition: because of their smaller size,
black bears can exist at 10x the density of grizzly bears on the same range, can live in habitats with a lower abundance of
fleshy fruits, and may reduce fruit availability to the extent that grizzly bear reproduction and occupancy is affected. Where
meat is a minor portion of the diet, black bears are notably fatter than sympatric grizzlies (McLellan 2011).Competition among bears will never be as great a threat to any species as anthropogenic effects, but it should not be
neglected. The low degree of overlap among modern bears suggests that competition has been an active force in their
evolution. Coexistence of two species of bears is a delicate balance: changing the conditions of this balance ever so slightly
— through hunting, human-caused alterations of habitat, or climate change — could tip the scales in favor of one over the
other.
Our current state of knowledge is insufficient to predict the interspecific dynamics that could impact bear conservation.
For example, some recent work in Southeast Asia suggests that the relationship between Asiatic black bears and sun bears
may be related both to habitat conditions and human exploitation (Scotson 2010, Steinmetz 2011, Steinmetz et al. 2011).
Further work by Scotson (see article below) represents an effort to better understand this dynamic between species of bears
and how it is affected by continuing human-imposed threats.
We will have learned from our mistakes if T. floridanus remains the last bear species to go extinct.
1 If someone is aware of a more recent ursid species extinction, please let me know.
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