Mapping behavioral landscapes for animal movement: a finite mixture modeling approach

1. What they did

Urban growth is a major threat to carnivores such as bobcats, and conservation planners need to know how animals move around urban areas. The authors developed a new statistical method, a finite mixture model, that sorts an animal’s movement steps into different behavioural responses to a landscape feature, and links the chance of each response to the surroundings.

They applied it to GPS data from three bobcats in Orange County, California, recorded at night every 15 minutes, testing how the bobcats’ direction of travel related to the amount and direction of urban land within 200 m. They compared 11 models for each bobcat, then mapped the most likely behaviour across the landscape to create a “behavioural landscape”.

2. What they found

• All three bobcats avoided urban areas more strongly as urban cover around them increased, either by moving away from it or by moving parallel to the urban edge.
• The resident male moved roughly at random where there was little development, then shifted to moving parallel to the edge or towards development, and finally away from urban areas as urban cover rose.
• The resident female moved parallel to the urban edge even at low levels of urban cover, then away from urban areas at higher levels, suggesting she avoided urbanization more than the male.
• The wide-ranging male, whose area of use was about ten times larger and whose movements looked like dispersal, avoided urban areas only by moving parallel to the edge, starting abruptly when urban cover reached 8%. He was never recorded where urban cover exceeded 14%.
• The resident bobcats switched to moving away from development when urban cover within 200 m reached about 20% to 30%.
• Mapping these responses showed areas a bobcat would likely avoid, areas where moving along the urban edge could actually channel a bobcat through a corridor, and areas with no response to development.

3. What they concluded

Finite mixture models can classify movement into behavioural states when the behaviour cannot be observed directly, and the resulting behavioural landscapes can show which corridors are likely to be passable for an animal. The approach can include other landscape features and could guide conservation planning for connectivity. Because the bobcats were tracked only late at night, their responses may be the weakest; time of day, internal state and other features deserve study.

7. Implications for conservation (from the paper)

• Behavioural landscape maps can help identify corridors that are likely or unlikely to be used, prioritize conservation work, and predict connectivity under future land use.