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Earlier parturition date with warmer summers for smooth snakes (Coronella austriaca) in
Norway
JOHANSEN, B.S.
Natural History Museum and Botanical Garden, University of Agder, Gimleveien 27, Gimle
Gård, 4630 Kristiansand, Norway
SØRENSEN, P.
Bodøgata 2, 0565 Oslo, Norway
NYBERG, S.O.
Dept. of Technology, University of Agder, Postboks 509, 4898 Grimstad, Norway
The reproductive ecology of smooth snake, Coronella austriaca, is poorly understood as mating
and parturition rarely have been documented. In Norway, the smooth snake lives on the northern
border of its distribution. At these latitudes, it is unknown whether the summers are long enough
for the females to mate, fulfil the pregnancy and give birth before hibernation. There are also
concerns about how global climate change may influence the reproduction in this rare species. It
is red listed but as Least Concern on Europe/Global level, and Near Threatened on National level.
This study shows that the Norwegian smooth snakes have an extended mating period, both during
spring and autumn. We also report how the parturition date varies with summer temperature. Our
results display that deviation from average temperature during July significantly influences the
parturition date. In Kristiansand, southern Norway, the birth date was also influenced by average
temperature deviations in June and August. The warm and dry summer climate along the
southern coast of Norway does forward the gestation period of gravid females and parturitions to
mainly August, the same time as in continental Europe. The climate change prognoses along the
southern coast of Norway are warmer summers and wetter winters with more heavy rain or
snowfall. This study demonstrates that warmer summers may have a positive impact on the
female smooth snake gestation period. Further research is needed to evaluate the effect of wet
winters on hibernating reptiles.
Key words: Smooth snake, Coronella austriaca, parturition date, climate change, mating period
