Apart from the spring migration that takes place in early April around Tomb Sweeping Day, Chan Chia-lung was also the first to discover a second migration of crow butterfly species in early summer.
除了每年 4 月初清明節前後集體北返的「春季遷移」外，詹家龍也首次發現了初夏新生紫斑蝶的「二次遷移」現象。