What impact does a stressful environment have on an animal's behavior?

A stressful environment can significantly alter an animal's behavior, and one prominent outcome of such stress is an increase in anxiety and aggression. When an animal is subjected to stressors—whether they are environmental changes, threats, or social conflicts—it may trigger a heightened state of alertness and defensive behaviors. This behavioral shift is rooted in the animal's instinctual responses to threats, which can manifest as aggression when they feel cornered or vulnerable. Additionally, prolonged exposure to stress can lead to chronic anxiety, impacting an animal's overall well-being and ability to function normally in its environment.

In contrast, the other options suggest outcomes that are generally less common or counterproductive in the context of stress. Stress does not typically foster improvements in social skills or resilience; instead, it can lead to maladaptive behaviors that hinder social interactions. Thus, the effect of stress on animals is predominantly negative, often exacerbating anxiety and leading to aggressive responses as a survival mechanism. Understanding this relationship is crucial for anyone working with animals, as it highlights the importance of creating a stable and supportive environment to minimize stress and promote healthy behaviors.