Patterns of post-hibernation wing damage healing in little brown bats (Myotis lucifugus) impacted by white-nose syndrome

Bats recovering from white-nose syndrome post-hibernation exhibit two main types of wing damage: black dots and white spots. We developed and validated a scoring system to quantify this damage in a repeatable manner and assign bats 1 of 6 wing scores. Black dot cover peaked in May and wing scores improved over the summer. The patterns of recovery from injury or infection are not well studied in free-ranging animals. Bats that survive the fungal disease white-nose syndrome (WNS) often emerge from hibernation suffering from skin infections and wing damage. The extent of wing damage reflects physiological and immunological responses to WNS and may impact the ability of bats to fly, forage, and reproduce. Here, we built on previous studies of wing damage in both captive and free-ranging bats to better understand the patterns and extent of wing damage healing in little brown bats (Myotis lucifugus) post-hibernation. We quantified two main types of wing damage, black necrotic dots and white spots, and used the extent of damage to assign bats 1 of 6 wing damage scores. We found that the patterns of black dots and white spots on wing membranes of free-ranging bats aligned with the patterns observed in captive bats soon after emergence from hibernation. Black dot extent was highest at the beginning of the active season in May, while white spot extent peaked 3-4 weeks later. Our study also extends our knowledge of wing damage healing throughout the active season. Wing scores of bats recaptured within the summer decreased or stayed the same and >95% had negligible signs of wing damage by August. We found that black dots were more indicative of disease status than other types of wing damage and could be consistently quantified in the field and from photographs by multiple observers. These results suggest that black dots and our wing damage scoring system can be used to better understand the patterns of post-hibernation healing in little brown bats impacted by WNS.