Download Application of ecological research to the conservation efforts of

Application of ecological research to the conservation efforts of
Helarctos malayanus, the Malayan sun bear
Jocelyn Stokes
Introduction
Helarctos malayanus, the sun bear, is the smallest (27–65 kg) of all bear species. They are
also the least known and least studied species of bear (Wong et al. 2004). The sun bear pelage is
dark black with a distinct chest-patch that is typically U-shaped and ranges from cream colored
to bright yellow (Fitzgerald and Krausman 2002). Sun bears are omnivorous with an
opportunistic diet (Fredriksson et al. 2008). They are recognized as the most arboreal of bears
with their specialized bowed forelimbs, their inwards-curving paws, and their long, adept claws.
Sun bears are also distinguished by their extremely long tongue and protruding lips which are an
assumed adaptation for acquiring honey and larvae from bees’ nests (Corlett 2011, Fitzgerald
and Krausman 2002).
Although sun bear populations historically have a wide dispersal throughout the tropical
rainforests of Southeast Asia, there is a pronounced deficit in fundamental data relating to this
species (Normua et al. 2004, Wong et al. 2004). Sun bears are still extant in Peninsular
Malaysia, Sumatra, Borneo, Palawan and the Philippine islands; however, the species is rare,
except in Borneo (Wong et al. 2005). For this reason, the majority of research studies have been
based in Borneo; therefore, this paper focuses on the sun bears of Borneo. Borneo tropical
rainforests are scientifically renown as one of the most biologically diverse ecosystems on
Earth, yet these forests have been drastically reduced in most recent decades due to logging and
agricultural conversion (Wong et al. 2004, Wong et al. 2005).
The lack of information known about sun bears is critically limiting to their conservation.
Although previously listed as “data deficient” by the International Union for Conservation of
Nature (IUCN), sun bears are now recognized on the IUCN red list as vulnerable due to extreme
habitat loss and poaching (Fredriksson et al. 2008). A multitude of sun bear populations have
gone extinct, and the total species population count is estimated to be less than 25% of their
historic numbers (100 years ago) due to habitat-loss alone (Wong et al. 2005). This paper will
review the most recent studies on sun bear ecology, in regards to their feeding and habitat
needs, while considering the application of these findings in light of current conservation
concerns.
Methods
In researching Helarctos malayanus and sequestering peer-reviewed literature on the
topic of sun bears and their ecology, I utilized two web-based databases: Web of Science, from
the provider Thomson Reuters, and Wildlife & Ecology Studies Worldwide, from the provider
EBSCOhost. In my search within these databases I used the keywords “sun bear,” and
“Helarctos malayanus”. I also accessed the Mammalian Species Accounts from the American
Society of Mammalogy on-line source and retrieved the biological account of H. malayanus,
which is under the Order Carnivora, Family Ursidae, and Subfamily Ursinae, listed as account
number 696. I reviewed seven individual field surveys that studied the eating habits and habitat
usage of sun bears within their natural forest habitat.
Results & Discussion
Sun bears are known to feed primarily on invertebrates and wild fruits, serving the
ecosystem as important seed dispersers (Ngoprasert et al. 2011, Wong et al. 2005). Several
morphological adaptations suggest sun bears evolved to exploit these two main food sources,
such as their arboreal features of small body size, long claws, inward-facing feet and naked
soles; as well as, their insect feeding features of mobile lips, a bare snout, large paws and the
longest tongue amongst ursids (Fredriksson et al. 2006). The studies reviewed here surveyed
bears within primary forest, as well as logged forests, and share some relatively similar findings
about the feeding habits of sun bears.
Sun bear feeding habits have been found to vary seasonally in correlation with the
fruiting season of their native forests. For instance, in the Sugai Wain Protection Forest, of East
Kalimantan, sun bears were recorded to feed on >50 different plant species depending on where
food was abundant (Wong et al. 2002). The proportion of each food consumed during the year is
intrinsically linked to the “mass fruiting” cycles of their forest habitat. These ‘cycles’ refer to the
phenomenon occurring in the lowland tropical rainforests of Borneo where a diverse array of
fruit trees display a synchronized mass reproduction episode (Wong et al. 2004). During the
mass fruiting events, sun bears were found to be almost entirely frugivorous with fruits found in
approximately 98% of collected scat (Fredriksson et al. 2006). During the intervals between
mass fruiting cycles, studies suggest that sun bears are prone to periods of emaciation and
starvation (Wong et al. 2005). During these periods, studies show that sun bears rely heavily on
invertebrates, such as termites, beetles and larvae. In a two-year study done in Sabah, Borneo,
60% of all the feeding sites found were near decaying wood (housing termites, beetles and other
insects) and 63% of 56 scat samples contained beetles, which indicates the importance of
invertebrates, especially beetles, as a primary food source (Wong et al. 2002).
These studies also shared findings in the importance of figs in a sun bear’s diet during the
non-fruiting season. Fig trees fill the void of other wild fruits by displaying asynchrony with the
rest of the fruiting trees (Fredriksson et al. 2006). High in protein and calcium, figs are
considered a “keystone resource” to many tropical frugivorous species and appear to be the main
“fall-back’” fruit source for sun bears (Fredriksson et al. 2006, Wong et al. 2002). The
abundance of figs that sun bears consume indicates the importance of figs in their diet. One
example of high fig consumption was exhibited by the scat collection of a female bear who
defecated >7% of her entire body weight in fig seeds (Wong et al. 2002). Additionally, most of
the direct observations of sun bears that occurred during these studies happened while in the
direct proximity of a fig tree.
Habitat preference and necessity is related to the availability of food, which is why these
arboreal bears spend much of their time climbing the fruit trees of the lowland dipterocarp
forests of Borneo. Abundance of fig trees is significantly greater in primary forests, as is the
abundance of invertebrates, when compared to logged forests (Wong et al. 2002). Fig trees are
especially vulnerable to habitat disturbances due to their species-specific pollination strategy,
which requires a symbiotic relationship with fig-wasps. Fig-wasp populations are experiencing
local extinctions in logged forests; therefore, this mutualism is acutely sensitive to forest
fragmentation (Wong et al. 2002). If this pollination technique is disturbed it results in a failure
to produce fruit, which has shown a devastating effect on sun bear survival. Several cases of
starvation were fatal to individual sun bears under surveillance during a period of low-fruiting
(Wong et al. 2002). Sun bears are adapted to traveling in search of food, with movement directly
related to the prevalence of fig trees. The average home range of four Malayan sun bears during
one study was 14.8 km2, ranging from 6.2 to 20.6 km2 (Wong et al. 2004). Evidence suggests
that fruiting fig trees and a large home range are essential attributes for sun bear habitat (Wong et
al. 2004, Fredriksson et al. 2006). Intact forest habitat is therefore directly influential in the
survival of sun bear populations. The drastic levels of deforestation in Borneo have lead sun
bears to experience an increase in habitat loss, which typically results in either human-conflict
issues or starvation (Ngoprasert et al. 2011, Wong et al. 2005).
During a documented period of low-food-availability, multiple sun bears under
surveillance were exhibiting “very poor” physical condition due to starvation (Wong et al. 2005).
One of these bears was later known to exploit a garbage dump, which is standard behavior
amongst opportunistic bears experiencing a void of available natural foods (Wong et al. 2005).
With increased habitat loss, situations such as this occur more frequently. Under these
circumstances bear behavior is generally considered to be a nuisance to humans and perhaps
even a threat (Ngoprasert et al. 2011). Commonly, this results in human-conflict issues that are
problematic for bear survival (Wong et al. 2004, Ngoprasert et al. 2011,Wong et al. 2005).
There are many conservation concerns that arise with the mounting awareness of how
habitat loss affects the continued survival of sun bears. Deforestation and forest fragmentation is
directly affecting the ability of sun bears to live sustainably throughout the natural cycles of their
forest habitat. Habitat loss and human disturbance is negatively impacting sun bear ecology by
creating sustenance issues and a lack of territorial safety. Further studies of variables that may
assist sun bears in their survival are critical. I encourage investigative studies on the impact of
supplemental nutrition introduction. This could be introduced into areas of sun bear habitat that
are lacking the necessary amount of naturally-occurring food sources due to human-induced
circumstances. Although further alteration to the native ecosystem is neither ideal nor
recommended, data attaining to the prevention of sun bear starvation in the wild may become
pertinent to their population status if they continue to experience extreme habitat loss.
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