AnimDens NetLogo Model

Latest version available at


NetLogo required to use the model. Available for free here.

This is a NetLogo implementation of the AnimDens model, originally programmed in R by Christine Ward-Paige, Joanna Mills Flemming and Heike K. Lotze. The original code can be downloaded here.


This is a model that simulates divers counting sharks while deploying belt-transect, stationary-point-count and roving underwater visual census techniques. The model demonstrates how non-instantaneous sampling techniques produce bias by overestimating the number of counted animals, when they move relative to the person counting them.

This is applied to divers and sharks, but is intended to reflect what happens with many other animal censuses (aerial surveys, bird transects, etc.).The model can be used to demonstrate that bias increases as the speed of the animals relative to the observer increases. Using the provided bias calculator, it is possible to use the output of the model to apply bias correction to field data.


If you use this model, please cite the original publication:

Ward-Paige, C.A., Flemming, J.M., Lotze, H.K., 2010. Overestimating Fish Counts by Non-Instantaneous Visual Censuses: Consequences for Population and Community Descriptions. PLoS ONE 5(7): e11722.


In order to cite the NetLogo implementation:

Pais, M.P., Ward-Paige, C.A. (2015). AnimDens NetLogo model.