Linking monitoring and intervention for improved management of tigers in the Sundarbans of Bangladesh

Baseline data on distribution and abundance of tigers in the Sundarbans is required to identify problem areas and evaluate management strategies. This paper outlines a khal (creek) bank survey of track set frequency throughout the Bangladesh Sundarbans to aid formulation of a management-driven monitoring program. Three teams of two observers surveyed a total of 1201 km of waterways throughout the Sundarbans, recording 1338 tiger track sets. These sets became unrecognizable as tiger sign after a mean 10 days (range 614). Proportion of detectable sign recorded was 0.91. Mean (+/- standard error) sample unit track frequency was 1.12 +/- 0.86 track sets/km of khal. The mean coefficient of variance in sample unit track rate, estimated by multiple counts of six sample units, was 0.21 (range 0.06-0.34). Track frequency generally increased from northeast to southwest. Four sample units (6%) had signs of reproduction, with a mean litter size of 1.75 +/- 0.5. Monte Carlo simulation suggests a monitoring program of one complete survey every two years will have power of 0.8 (alpha = 0.2), to detect track frequency declines of >= 19% and increases of >= 17%. We recommend this monitoring scheme be implemented on the Indian side of the Sundarbans to provide a standard assessment of the tiger population and to form the basis for setting management objectives and evaluating transboundary conservation initiatives. (C) 2008 Elsevier Ltd. All rights reserved.