Définition du « jizz »

What does the word « jizz » mean ? Contrary to the view of many people that « jizz » is a jargon term used exclusively by birders, or one which really belongs in another world such as that of the military, « jizz » is found in basic references such as the « Handbook of the Birds of the World and in ornithological dictionaries. For example, « A Dictionary of Birds » by Campbell and Lack (1985) defines the « jizz » as « a combination of characteristics which identify a living creature in the field, but which may not be distinguished individually ». The glossary in Simpson and Day’s (1993) « Field Guide to the Birds of Australia » defines the « jizz » as « a word used by twitchers to describe everything about a bird in one, all-embracing term, the essence or character  of a bird in the field ».
In this article, thanks to Roberto Garavaglia, redactor of the Italian website Ebnitalia.it and to the Australian birder David McDonald, we present you this term and its possible origin.