Age structure of Tsushima leopard cats killed by traffic-related causes on the Tsushima Islands, Japan

The ages of 42 Tsushima leopard cats killed by traffic accidents between 1997 and 2008 were determined by counting cementum annuli and assessing body size and the condition of teeth replacements. Additionally, body condition was estimated by external veterinary examinations. We assessed the relationships between cat age and the occurrences of traffic accidents. The ages of cats ranged from 0- to 9-years-old, more than 70% of which were yearlings. However, 2- to 4 year-old cats were not found among the dead; thus, the age distribution of the accident victims was biased toward yearling and older individuals. Traffic-related mortality among male yearlings occurred frequently from autumn to winter (September-January) and did not overlap with the time of year when>1-year-old individuals frequently suffer from traffic accidents, except in September. Traffic-related mortality among yearling females occurred most frequently in November. Yearlings, which are generally born in spring and become independent of their mothers in autumn and winter, lack experience of artificial dangers such as cars. Furthermore, yearlings must make long trips to cross paved roads until they settle in their own home ranges. Thus, yearlings tend to frequently suffer from traffic-related accidents. The deaths of subadults without clinical problems and of resident cats in traffic accidents are likely to have negatively affected the population levels of this endangered species.