Dietary adaptations along the northern limit of distribution: What does
the smooth snake (Coronella austriaca) eat in Norway? Metabarcoding of
stomach content and visual analysis of faeces.
Abstract
Abstract Understanding how species survive at their poleward limits of
distribution is of interest in species conservation, particularly in
light of global warming and predictions of shifting distributions of
both predators and prey species. How species adapt to high latitudes and
to future climate changes will be impacted both by direct interactions
with the environment, such as changing heat tolerances, but also
indirectly through biotic interactions with prey and predators. The
smooth snake (Coronella austriaca) in Norway provides an interesting
case study of biotic interactions at range limits. The number of
potential prey species of C. austriaca is lower in Norway than in
southern latitudes. To investigate trophic adaptations at its poleward
range limit we used metabar-coding sequencing to identify prey species
in stomach samples of a museum collection of 17 preserved C. austriaca
from Agder in Southern Norway. Eight prey species were detected, four
reptiles and four mammals. Field vole (Microtus agrestis) and common
shrew (Sorex araneus) were the most common prey species, while bank vole
(Myodes glareolus) and wood mice (Apodemus sylvaticus) were eaten only
by a few smooth snakes. A. fragilis was found in five samples and Z.
vivipara in only three samples. DNA was also recovered from grass snake
(Natrix natrix) in all but one sample, and DNA from European adder
(Vipera berus) in one sample, indicating the role of ophiophagy. Visual
analysis of 75 faeces from the Oslo region showed that A. fragilis was
the most common prey species, followed by shrews. The main conclusion is
that C. austriaca in Norway have a higher proportion of mammalian prey
in their diet compared to populations in more southern latitudes.