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| Beyond broad-scale investigations of species diversity and abundance, there is little
information on how land conversion in the tropics is affecting the behavior and
demographics of surviving species. To fill these knowledge gaps, we explored the
effects of land-use change on the ecologically important and threatened bearded
pig (Sus barbatus) over seven years in Borneo. Random placement of camera traps
across a land-use gradient of primary forest, logged forest, and oil palm plantations
(32,542 trap nights) resulted in 2,303 independent capture events. Land-use was
associated with changes in the age structure and activity patterns of photographed
individuals, alongside large changes in abundance shown previously. The proportion
of adults recorded declined from 92% in primary forests to 76% in logged forests,
and 67% in plantations, likely indicating increased fecundity in secondary forests.
Activity level (capture rate) did not vary, but activity patterns changed markedly, from
diurnal in primary forests, crepuscular in logged forests, to nocturnal in plantations.
These changes corresponded with avoidance of diurnal human activity and may also
protect bearded pigs from increased thermal stress in warmer degraded forests. The
percentage of adult captures that were groups rather than individuals increased fivefold
from primary forests (4%) to logged forests (20%), possibly due to increased
mating or in response to perceived threats from indirect human disturbance. We recommend
further investigation of the demographic and behavioral effects of land-use
change on keystone species as altered population structure, activity patterns, and
social behavior may have knock-on effects for entire ecosystems. | |
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