' s ▁Or n ith ology ▁was ▁intended ▁to ▁describe ▁all ▁the ▁then - known ▁birds ▁world wide . ▁Its ▁innov ative ▁features ▁were ▁an ▁effective ▁classification ▁system ▁based ▁on ▁an atom ical ▁features , ▁such ▁the ▁bird ' s ▁be ak , ▁feet ▁and ▁overall ▁size , ▁and ▁a ▁dich ot om ous ▁key , ▁which ▁helped ▁readers ▁to ▁identify ▁birds ▁by ▁gu iding ▁them ▁to ▁the ▁page ▁describing ▁that ▁group . ▁The ▁authors ▁also ▁placed ▁an ▁a ster isk ▁against ▁species ▁of ▁which ▁they ▁had ▁no ▁first - hand ▁knowledge , ▁and ▁were ▁therefore ▁unable ▁to ▁verify . ▁Will ugh by ▁had ▁been ▁keen ▁to ▁add ▁details ▁of ▁" character istic ▁marks " ▁to ▁help ▁with ▁identification . ▁The ▁authors ▁also ▁largely ▁avoided ▁the ▁practice ▁of ▁previous ▁writers , ▁such ▁as ▁Con rad ▁G ess ner , ▁by ▁not ▁including ▁extr aneous ▁material ▁rel ating ▁to ▁the ▁species , ▁such ▁as ▁pro ver bs , ▁references ▁in ▁history ▁and ▁literature , ▁or ▁use ▁as ▁an ▁em blem . ▁The ▁book ▁was ▁published ▁in ▁Latin ▁as ▁Or n ith ologia e ▁Lib ri ▁T res ▁( Three ▁Books ▁of ▁Or n ith ology ) ▁in ▁ 1 6 7 6 . ▁ ▁The ▁first ▁of ▁the ▁three ▁sections ▁included ▁an ▁introduction ▁to ▁bird ▁bi ology , ▁an ▁explanation ▁of ▁the ▁new ▁classification ▁system ▁and ▁the ▁dich ot om ous ▁key . ▁The ▁second ▁and ▁third ▁sections ▁described ▁land ▁birds ▁and ▁se ab ird s ▁respectively . ▁Emma ▁Will ugh by ▁paid ▁for