Bad hare day: Very low survival rate in brown hare leverets

Abstract

Increased postnatal leveret mortality has been identified as the proximate factor explaining the decline of European brown hare Lepus europaeus populations in Europe. However, direct measurements of survival rates are non-existent as the leveret's cryptic behaviour makes them very difficult to study. Previously, leveret survival rates calculated using hunting bag statistics or capture-mark-recapture methods have been estimated to lie between 5% and 56% for the period between the start (January) and the end (October) of the breeding season. Such indirect approaches are known to yield inaccurate results compared to direct survival measurements. Hence, we applied novel detection methods and radio-tagged 63 wild-born leverets (aged between 1 and 22 days at capture) in two different populations in the Swiss lowlands. We located the tagged individuals daily to monitor individual fates and to directly calculate survival probabilities. We found that leveret survival is negatively influenced by precipitation. However, when leverets use edge habitats, survival is positively influenced. Daily survival rate and survival probability for the first month of life were found to be 0.94 and 0.18 respectively. Such low survival is alarming and to prevent further declines in populations of brown hares, it will be essential to mitigate against these excessive losses. Therefore, we suggest measures aimed at increasing the area of suitable habitat for leverets, where they can grow up safely (e.g. shelter from predators and bad weather).