Sentence:  A West Coast Irishman was familiar with the wild creatures which dwelt on or visited his rocks and shores; at a glance he could name them, usually correctly, but if asked how he knew them would reply ‘By their "<WSD>jizz</WSD>".' 
Meaning of the word marked with <WSD> tags:  The unique characteristics of a bird species that enable it to be immediately identified by an experienced birdwatcher who has seen that bird before and is familiar with its appearance and behaviour.