Dynamics of Complex Living Systems

Animal movement and encounter theory


A lot of the ecological theory developed during the last one hundred years, from models of species interactions to mathematical epidemiology, assumes that organisms interact with each other following the ‘law of mass action’. This encounter model, although mathematically simple, is incorrect for most real scenarios because it assumes that organisms roam freely in their entire environment and are thus equally likely to interact with any other organism they share the environment with.  Our research has provided a new family of encounter models that relax this well-mixed assumption and account for the patterns of movement behavior observed in animal tracking data. We have shown that these more realistic encounter rates could either be higher or lower relative to mass action and sensitive to the details of the movement behavior, which has profound implications at higher ecological scales as well as in determining the rate at which animals interact with different landscapes features such as road or power lines.

Selected references:

Dornelas, V., de Castro, P., Calabrese, J. M., Fagan, W. F., & Martinez-Garcia, R. (2023). How movement bias to attractive regions determines population spread and critical habitat size. arXiv preprint arXiv:2306.06450.
Nauta, J., Simoens, P., Khaluf, Y., & Martinez-Garcia, R. (2022). Foraging behaviour and patch size distribution jointly determine population dynamics in fragmented landscapes. Journal of the Royal Society Interface, 19(191), 20220103
Noonan, M. J., Martinez‐Garcia, R. et al., (2021). Estimating encounter location distributions from animal tracking data. Methods in Ecology and Evolution, 12(7), 1158-1173.
Martinez-Garcia, R., Fleming, C. H., Seppelt, R., Fagan, W. F., & Calabrese, J. M. (2020). How range residency and long-range perception change encounter rates. Journal of Theoretical Biology, 498, 110267.