New Tamaraw Census Using Double Observer Method Confirms Population Below 300 at Mounts Iglit-Baco Natural Park - BULLetin Issue 9

Accurate estimation of endangered species populations is critical for wildlife managers and conservationists. Equally important is assessing the reliability of the method used and the uncertainty associated with the results. For these reasons, the double observer estimator method, combined with point count (direct field observations), was introduced at Mounts Iglit-Baco Natural Park—the site of the largest known population of the critically endangered tamaraw (Bubalus mindorensis) on the island of Mindoro, Philippines.

The D’ABOVILLE Foundation (DAF) has supported local authorities in implementing this census approach to refine estimates of the true number of tamaraw within the core monitoring zone of the protected area. Since 2022, this operation has been conducted in parallel with the annual tamaraw population count, which lacks the capacity to provide confidence intervals. A dedicated statistical model was developed through scientific collaboration with the French Center for Scientific Research (CNRS) and the University of Lyon to analyze results in a standardized manner.

Findings from this fourth iteration corroborate previous years:

• The traditional count consistently overestimates tamaraw numbers.

• The population is closer to 260 animals, with an uncertainty margin of ±60.

This article elaborates on these results and discusses how they should be interpreted.

We extend our gratitude to the Asian Wild Cattle Specialist Group (IUCN-SSC) for publishing our work in this new edition of the BULLetin.

(P.11-14 in BULLetin issue 9)

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