The threat to survival posed by predation shapes many aspects of prey species life history, including habitat selection. Prey may select visual concealment, escape cover, and/or olfactory concealment to reduce predation risk. Olfactory concealment, the degree to which an animal conceals itself from olfactory detection, can be provided through airflow patterns such as updrafts or high turbulence. These airflows can diffuse and/or disperse prey odorant plumes, making them more difficult for predators to detect and follow. Our objectives were to identify vegetative features that affect variation in olfactory concealment. To accomplish this, we used a 3D sonic anemometer to measure turbulence and updrafts at ground level within grassland, shrubland, and woodland vegetation types. We then related these airflow metrics to vegetative features hypothesized to affect turbulence and updrafts (e.g., vegetation height and visual concealment).
Results/Conclusions
For each vegetation type, top models explaining variation in turbulence contained vegetation height and visual concealment; both variables had positive relationships with turbulence. We found no relationships between updraft and vegetative features. Our results indicate that prey species should select areas with tall vegetation and high visual concealment to increase turbulence and thereby reduce the risk of predation by olfactory predators. To date, very few studies have examined turbulence as a component of habitat selection, and indeed, only one study has documented selection based on olfactory concealment (a study illustrating that grouse select high-updraft locations for loafing sites). However, numerous habitat selection studies have evaluated visual concealment and vegetation height, with some linking selection of higher visual concealment with increased reproductive success. Because olfactory-based predators often comprise a large component of predator communities, we argue that in many cases, apparent selection for visual characteristics of cover may indicate selection for olfactory concealment. To fully understand how animals select habitat—especially for animals primarily predated by olfactory predators—ecologists should consider olfactory concealment in addition to more traditional visual concealment metrics.