How do flying squirrels and colugos glide without flying like bats?

Flying squirrels and colugos do not engage in powered flight like bats; instead, they perform gravitational gliding. While bats possess wings adapted for true flight, these gliding mammals rely on a specialized fold of skin called a [patagium].12

This membrane extends along the sides of the body, typically connecting the forelimbs to the hind limbs. When these animals leap from trees, they assume a spread-eagle posture, causing the patagia to unfold and increase their surface area. This transformation turns their bodies into a gliding platform that creates wind resistance, allowing them to sail downward toward a target.312

Unlike the complex anatomical modifications required for powered flight—such as the transformation of forelimbs into wings and the enlargement of thoracic muscles—gliding is a passive form of locomotion. By manipulating their membranes and tails, these animals can control their descent and direction, but they lack the ability to generate the sustained lift and propulsion characteristic of true flight.234