Comparing spatial capture–recapture modeling and nest count methods to estimate orangutan densities in the Wehea Forest, East Kalimantan, Indonesia
Date
2015-11Author
Spehar, Stephanie N.
Loken, Brent
Rayadin, Yaya
Royle, J. Andrew
Metadata
Show full item recordAbstract
Accurate information on the density and abundance of animal populations is essential for understanding species'
ecology and for conservation planning, but is difficult to obtain. The endangered orangutan (Pongo spp.) is an
example; due to its elusive behavior and low densities, researchers have relied on methods that convert nest
counts to orangutan densities and require substantial effort for reliable results. Camera trapping and spatial
capture–recapture (SCR) models could provide an alternative but have not been used for primates.Wecompared
density estimates calculated using the two methods for orangutans in the Wehea Forest, East Kalimantan,
Indonesia. Camera trapping/SCR modeling produced a density estimate of 0.16 ± 0.09–0.29 indiv/km2, and
nest counts produced a density estimate of 1.05 ± 0.18–6.01 indiv/km2. The large confidence interval of the
nest count estimate is probably due to high variance in nest encounter rates, indicating the need for larger sample
size and the substantial effort required to produce reliable results using this method. The SCR estimate produced
a very low density estimate and had a narrower but still fairly wide confidence interval. This was likely due to
unmodeled heterogeneity and small sample size, specifically a lownumber of individual captures and recaptures.
We propose methodological fixes that could address these issues and improve precision. A comparison of the
overall costs and benefits of the two methods suggests that camera trapping/SCR modeling can potentially be
a useful tool for assessing the densities of orangutans and other elusive primates, and warrant further investigation
to determine broad applicability and methodological adjustments needed.
URI
https://doi.org/10.1016/j.biocon.2015.06.013http://repository.unmul.ac.id/handle/123456789/3694
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- J - Forestry [356]