Relationship between point count and line transect

[Mei-Ling Bai]

Dear distance group members,

I am curious about the relationship between the parameters in the distance sampling of line transect and point count.

Say, if one has good data from a line transect survey, and  has derived the detection function of the focal species. Suppose that someone else conducted point count survey of the same species in a similar region, but the sample size is not enough to derive a detection function. Is the information from the line transect survey (e.g. detection function, ESW, and distribution of animal-to-observer distance) of any reference value to the point count survey, after some mathematical transformation?

Thanks  a lot and best wishes,

Mei-Ling

[Eric Rexstad]

Mei-Ling

It is hard for me to imagine a way of employing detection function parameters from a line transect survey in a point transect survey.  Recognise there are two processes giving rise to detections:  1) the distribution of animals with respect to the transects and 2) the filtering of those animals by the detection process.  Process 1) differs between lines and points; animals are assumed distributed uniformly at all distances with line transects, but with points, geometry argues there are few animals available to be detected at distances close to the observer and large numbers of animals available to be detected at large distances from the observer.  I would be reluctant to apply a detection function from a line transect survey to a point transect survey.

Perhaps other boffins have alternative thoughts.

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Eric Rexstad
Centre for Ecological and Environmental Modelling
University of St Andrews
St Andrews is a charity registered in Scotland SC013532