Fear changes traits and increases survival: a meta‐analysis evaluating the efficacy of antipredator training in captive‐rearing programs

Abstract

Captive rearing is commonly used to support efforts to restore extirpated or diminished wild populations. Many rearing programs include antipredator training in an effort to reduce post‐release mortality due to predation, but the value such training adds to restoration efforts is not fully understood. Analyses of antipredator training impacts often focus on changes in prey following training and not the actual effects when prey are exposed to predators. Studies also commonly assess prey traits instead of fitness. However, changes in prey following training may not translate to desired increase in fitness upon release for a self‐sustaining population. To consider these relationships, we identified studies that analyzed changes in organisms following both training and lethal exposure to predators. Notably, we identified only 12 studies that analyzed outcomes in both training and lethal exposure settings and found the majority of measurements focused on traits. Although meta‐analysis indicated that antipredator training changed prey traits and increased prey survival, relationships between changes in traits and fitness could not be assessed given the rarity of studies that included both outcomes. While these results support the general use of antipredator training, they also suggest that trait changes cannot be reliably used as proxies for fitness impacts. Future work should seek to more clearly measure impacts on fitness and determine when changes in traits can truly be used as a surrogate for training efficacy. These issues reflect recent concerns regarding research on non‐consumptive effects and highlight potential avenues for future collaborative research on fear.