Chamois: a retrospective analysis of data collected in the Massif des Bauges regarding the Chamois (Rupicapra rupicapra) was undertaken in order to understand the influence of climatic conditions on the demography of this species.
Methodology: since 1985, the dates of calving of marked female chamois have been determined by visual observation in the field in the Réserve Naturelle de Chasse et de Faune Sauvage of the Massif des Bauges. The principle was to observe marked females until calving in the spring as frequently as possible. This makes it possible to determine the date of calving of the marked females.
Results: mean calving dates vary greatly from year to year. Between 1993 and 2011 the mean calving date was May 30 (Julian date 149) and 2011 began particularly early (see figure below).
Calving dates can be influenced by climatic conditions at the time of calving but also those of the previous months. Thus, the food resources of the previous year affects the health of females and thus calving in the following year. Then the severity of the winter, including such factors as the duration of snow cover, have a direct impact on the timing of births in the following year. Finally, an early spring also influences the birth dates. Calving dates fall earlier in spring when mean temperatures were warmer and the productivity of plants higher (measured via NDVI, see Figure 2).
Figure 2: Date of birth (Day of year) according to: a) temperature in May, b) NDVI in May. Years used in the analyses: 1993, 1994, 1996, 1998, 1999, 2000, 2002, 2003, 2004. Size of the red point indicates the precision of the estimation of date of birth. Julian date 149 = 30th of May
Advantage: chamois seems to be sensitive to climate change because the dates of calving females vary from year to year and may be related to climatic conditions.
Disadvantage: monitoring chamois is difficult to generalize across the Alps because it entails capturing substantial numbers of individuals for marking. These captures require extensive resources and time to produce good results. In addition, observations of females giving birth varies greatly from year to year due to the difficulty of observing individuals during this critical period and substantial efforts in terms of time and resources to identify the exact calving dates.