Constraints and demands interact to affect prey dietary reaction to predation

Prey alter their foraging when threatened by predators. Two mutually inclusive hypotheses explain this response. The first entails that defense behaviors to minimize exposure to predators prevent prey from achieving their preferred diet, while the second postulates that prey deliberately change their diet to fulfill new stress-induced nutritional demands. We combined field observations and laboratory experiments to determine which hypothesis dictates snail dietary responses to risk of beetle predation. Snails exposed to predation-risk reduced activity, increased climbing, increased respiration, ate distinctively to achieve a certain nutrient target, and preferred eating on the cage floor at the costs of nutritional imbalance and elevated risk. When only carbohydrates-rich food was on the floor, stressed snails reduced activity and foraged less, but when only protein-rich food was on the floor snails increased activity and consumed more carbohydrates than their no-risk conspecifics. This..., Snails' density- counting live snails in 1 square meter, in each microhabitat
Snails' activity and vertical location- observations
Snails' physiological stress- CO2 respiration rates
Snails' macronutrient consumption- weighing artificial food consumption  , , # Data from: Constraints and demands interact to affect prey dietary reaction to predation

[https://doi.org/10.5061/dryad.q2bvq83rr](https://doi.org/10.5061/dryad.q2bvq83rr)

Tha manuscript includes three experimental parts:

1. **Measuring snail density and behavior in the field**
To quantify the snail’s habitat use and activity, we randomly located 34 one square meter plots within the Loess Park Nature Reserve. In each plot, we recorded the number of snails in each patch type ( i.e., biological soil crust, perennial shrubs, or plant litter)  and noted whether snails were active or not. We also noted whether the snails were above or below a threshold height of 2 cm, since beetles pose much lesser risk above this height. In all plots, the relative area of each patch type was evaluated. The overall coverage could exceed 100% since shrubs canopy overlapped with other patch types. Based on these estimations we calculated the snail density in each patch type. During the observations we...