Chandra has always had a small mane, especially compared to his brother Sabu who used to live at the park. Although i do agree, it looks extremely thin there but i can assure you its not falling out
Is Chandra a particularly big male? When I saw them in the indoor quarters I was struck at his enormous size- very tall too. I've seen plenty of Asian Lions (including him at Bristol previously) but he just seems huge now- maybe its just the close viewing at CWP?