The wings of P. hesperus are hairless except for the lower third of the interfemoral membrane; the toes also have a light sprinkling of fine hairs.

Bats of this species inhabiting barren desert areas devoid of trees and rocky outcroppings must find an appropriately sheltered roost in which to spend the daylight hours or risk death.

One hypothesis is that P. hesperus spends the day in kangaroo rat burrows, but no evidence currently exists to support this.

[7] In some areas, the bats may roost in the piles of rocks used to anchor the soil along the bases of highway and railroad embankments.

Their low-aspect wings give these bats increased maneuverability, an important characteristic when hunting flying insects.

[9] P. hesperus will enter periods of hibernation when the weather grows cold or food supplies diminish.

However, both male and female members of this species will sometimes emerge during the winter months to hunt, though not in the numbers commonly observed during warmer times of the year.

[7][8] In keeping with their mostly solitary nature, females raise their young alone or in small maternity colonies of no more than a dozen bats.