Relationships between reproductive behaviours and mating in Vipera aspis: study in a natural population

Because breeding frequency is one of the main life-history traits, it is of fundamental importance to identify reproductive and non-reproductive indiv iduals in wild populations. However, most animal species exhibit secretive habits, and information must be extracted from fragmented behavioural seque nces. A natural population of Asp Vipers (Vipera aspis) was studied to exam ine reproductive behaviours in the field. Mating were rarely recorded, but preliminaries during courtship were more easy to observe. Courtship behavio ur is closely associated with mating and reproductive status, and thus enab led us to identify mated females as well as most of the reproductive (e.g. vitellogenic) females. In males, such preliminaries, which are the main sou rce of information on reproductive activity, showed strong individual varia tions between sexually-active and sexually-inactive adults. Long term monit oring suggested that several males can skip breeding opportunities in any p articular year. These results may help to study reproductive strategies in secretive animals such as snakes.