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Mortality of reintroduced Eurasian lynx (Lynx lynx) in Croatia

On March 2nd 2008 we have acknowledged the 35th anniversary of Eurasian lynx reintroduction to Dinaric Mountains. Six animals from Slovakia, released in 1973 in Slovenia, founded one of the most successfully reintroduced European lynx populations. Lack of prey and human prosecution led to extermination of the autochthonous lynx in Croatia around the year 1903. Reintroduced animals exhibited pronounced population growth and range expansion during initial 15 years, followed by a period of stabilization. During the last 15 years the Dinaric lynx population is decreasing. Eurasian lynx live at low densities occupying large areas ; have low reproductive and population growth rates. As such, their populations are unusually sensitive to increase in mortality and decreases in reproduction. Mortality of individuals is one of the basic parameters of population dynamics. General knowledge about the distribution and trend of mortality is important, because excessive mortality can have negative impacts. The aim of this study was to provide quantitative information on causes of lynx mortality in Croatia and to evaluate their effects on long-term population stability. During the 30-year period (1978-2007) a total mortality of 227 animals has been recorded. Yearly mortality ranged 1 – 17 animals, with 7.56 animals per year in average. First animal killed after the reintroduction was in 1978, and without protection until 1982, a total of 29 animals have been killed. Then lynx became protected and limited yearly hunting quota was issued. Last permit was issued in 1998 and after that mortality data were very sparse (total of 27 records), with 1 – 5 dead animals recorded per year, most of them being unproven, anonymous poaching reports. Out of all 227 mortality cases, only 2 (0.88%) were not due to human related causes (1 animal drowned in the sea and one kitten died of pneumonia), and in 10 cases (4.4%) cause of death was not identified. Recorded mortality was primarily due to human related causes: shooting (76.21%), traffic accidents (8.37%) and other (snares, poison, killing with rock, axe, wooden or metal poles, land mine) (9.69%). Until 2000 a total of 17 poaching cases were recorded (8.06%), while in the 2000-2007 period poaching caused 81.25% of the total mortality. Age was not determined for 15 animals (6.6%), 148 were older than one year (65.20%) and 64 younger than one year (28.20%). We suspect that overall lynx mortality in Croatia during this period was probably higher, but we were not able to record all cases. Especially poaching and infectious diseases are likely to be under-represented. It can be concluded that the high percentage of human induced mortality and especially the adult mortality could have played a mayor role in the current population decline which can threaten its survival and therefore should be closely monitored.

lynx; mortality; Croatia

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