Which solitary bat is known for roosting in tree cavities and cliff crevices?

The correct choice is Keen's Bat, which is well-documented for its solitary roosting behavior in tree cavities and cliff crevices. This species prefers to utilize these natural structures as shelter, providing a safe environment away from predators and harsh weather conditions while they roost during the day. Keen's Bat's affinity for these specific roosting sites is a key characteristic that distinguishes it from other bat species.

Contrastingly, options like the Hoary Bat, Red Bat, and Evening Bat have different roosting preferences. The Hoary Bat often roosts in foliage and is more commonly found in trees rather than relying on cavities. The Red Bat prefers to roost in the leaves of trees, typically in built nests composed of vegetation rather than tree cavities or cliff crevices. The Evening Bat generally favors transitioning habitats and urban areas for roosting, focusing on buildings or other man-made structures rather than natural cavities. Understanding these distinctions is crucial in the study of bat behavior and habitat preferences in California's ecosystems.