• Authors:
  • Emily Denief
  • Julie W. Turner
  • Christina Prokopenko
  • Alec L. Robitaille
  • Eric Vander Wal

This repository contains the code accompanying the paper “At a snail’s pace: the influence of habitat disturbance on terrestrial snail movement using experimentally manipulated mesocosms”.

This project depends on some incredible R packages. We use targets for declaring the workflow and renv for a reproducible environment. General processing using data.table and plotting with ggplot2 and patchwork. iSSA methods with amt, raster and sf, modeling with glmmTMB and lme4.

The Anthropocene marks great changes to environments and the animals that inhabit them. Changes, such as disturbance, can affect the manner in which animals interact with their environments, such as moving and selecting habitats. To test how animals might respond to changing disturbance regimes, we employ an experimental approach to movement ecology. We used integrated step selection analysis (iSSA) to test the behavioural responses of individually-marked grove snails (Cepaea nemoralis) exposed to a gradient of physical disturbance in their habitat. We used a before-after control-impact (BACI) experimental design within semi-controlled mesocosms to manipulate edge and disturbance variables by altering the area of the mesocosm covered by bricks. We showed that grove snails perceive edges of enclosures and edges of bricks as risks, and responded to such risks by altering their movement. Grove snails displayed a bimodal response to risk by taking shelter in place or moving faster to be farther from the disturbance. Furthermore, individuals tended to modulate their behavioural response to the degree of risk. Our study highlights the usefulness of experimental mesocosms in movement ecology and in determining the effects of habitat alteration and human-imposed risk on movement behaviour.