Mortality in the Eurasian lynx population in Croatia over the course of 40 years

Abstract

The combination of intensive persecution, habitat loss and prey deficiency led to the extinction of Eurasian lynx (Lynx lynx) in the Dinaric Mountains at the beginning of the 20th century. In 1973, the population was re-established by reintroducing animals from the Slovakian Carpathian Mountains into Slovenia, from where the animals spread into Croatia and Bosnia and Herzegovina. Since the end of the 20th century the reintroduced population has been decreasing, leading us to investigate the principal causes of mortality. Understanding the causes of the declining lynx population in Croatia and elsewhere is important not only in its own right but also because few studies have examined how large carnivore populations have fared under different management regimes. After reintroduction, the first dead lynx was recorded in Croatia in 1978, and from that year until 2013 a total of 232 deaths were recorded. Annual mortality during this period averaged 6.4 deaths per year, ranging from 0 to 17. The number of dead lynxes found every year in the period before the legal protection (1978–1998) was significantly higher than the number of dead animals found in the period after the legal protection (1998–2013). The vast majority of deaths were human-related (92.7%), with only 2.1% not human-related; while the cause of the remaining 5.2% of deaths was undetermined. Shooting was the most dominant cause of death (73.7%), with significantly more males being killed by shooting than females, and significantly more animals shot before the legal protection. Between 1978 and 1998, the year when the lynx became legally protected in Croatia, 10 deaths due to poaching were recorded, accounting for 5% of all deaths in that period and an average of 0.48 poaching cases per year. During 1999–2013, 18 poaching deaths occurred, accounting for 60% of all deaths in that period and an average of 1.2 poaching cases per year. Our findings suggest that the synergy of human-induced mortality, concomitant reduction in genetic variation and possibly prey deficiency may be the principal factors behind the decline in the reintroduced lynx population in Croatia since the end of the 20th century.