|The asp viper. Photo credit: Felix Reimann|
Rugieroa and colleagues (2013) have recently published an analysis of the changes in phenology which have occurred in the last 20 years in a marked population of the asp viper. And, they relate these changes to the intervening climatic changes. They examined three metrics of the viper's annual phenology: (1) annual onset of above-ground activity; (2) annual onset of feeding period; (3) annual onset of the hibernation. The annual variations of these three phenological metrics were correlated to five climatic variables: (1) mean annual air temperature, (2) mean February air temperature, (3) mean July air temperature, (4) yearly number of rainy days, and (5) yearly number of days with rainstorm.
The 20-year study revealed that the asp vipers have shifted at least three traits of their annual phenology in a way consistent with predictions of the theoretical responses for a reptile species to a warming climate. The asp viper increased both onset of annual activity and onset of the feeding, whereas they delayed their entering into hibernation. They also demonstrated that these shifts were signiﬁcantly correlated to yearly annual air temperature, and that the percent of ﬁeld days between 20th February and 20th March without observed vipers decreased over the years. However, they found no signiﬁcant pattern when analyzing the correlation between rainfall and phenological traits. Thus, their results suggest that changing temperature and not rainfall is driving viper phenology.
Rugieroa L, Milanab G, Petrozzic F, Capulad M, Luiselli L. 2013. Climate-change-related shifts in annual phenology of a temperate snake during the last 20 years. Acta Oecologica 51:43-48