Ontogeny of Flight Aptations (IMAGE) PLOS Caption Flight-capable adult birds have many morphological features that are presumably adaptations or exaptations for meeting aerial challenges. Large wings with stiff, asymmetrical primary feathers (A) are thought to stabilize feathers against oncoming airflow [48], prevent excessive deformation [23], and reduce feather permeability [49]. Credit <i>PLOS ONE</i> Heers AM et al. e0153446 Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.