A pilot study is essential to feed data into the programme development stages to ensure that future programme resources are used efficiently to target priority data gaps, that the scale and robustness of final survey are appropriate, and that survey design is matched to fundraising. To achieve an effective sampling design with sufficient transect repetitions the encounter rate and variance is required. In addition transects should be placed across known density contours, appropriate stratification units determined and if responsive movement occurs double platform sampling may be required. These data, unavailable at present, can be provided by a pilot study.
