He also wrote a bird diary out in the wilds, containing ecological observations, such as at what times certain birds shed their feathers and how their plumage changed color between winter and summer.
他也在野外寫過花鳥日記，內容是生態的觀察和研究，比如某種鳥類何時脫毛，冬、夏羽毛色澤如何區別等。