engleski

Negative temporal trend of early horn growth in European mouflon Ovis aries musimon

The development of horns in Caprinae species can be influenced by several variables. These may include food-limiting factors such as population density and climate, as well as negative evolutionary responses caused by human interventions such as trophy hunting. We investigated the long-term drivers of horn development in a population of European mouflon Ovis aries musimon introduced to a Mediterranean habitat in Croatia. After its introduction in the early 1980s, the population increased rapidly and reached apparent asymptotic size in the mid-2000s. Since the mid-1990s, the population has been subject to commercial trophy hunting on rams, and the temporal trend in early horn growth in 431 legally hunted mouflon rams was analysed over 14 years (1993–2007). Cohort-based linear models and analysis of deviance (ANODEV) revealed a significant negative trend in early horn growth, with a decline of c. 10% over the study period. Cohort population density was a major driver of such a decline, explaining about 61% of the temporal trend, as revealed by the ANODEV R2, while environmental covariates explained only about 7% of the temporal trend in horn size. Although we found a negative relationship between age at death and early horn growth, thus suggesting the occurrence of hunters’ selectivity towards large trophies, the actual effect of trophy hunting on the decline in horn growth is difficult to assess. Our results highlight the importance of food-limiting factors – density dependence above all – in explaining the decreasing trend. Yet, hunters’ selectivity should not be discarded. Data showed that 56 % of rams were harvested before reaching 5 years of age, thus suggesting potential negative consequences of trophy hunting. Evolutionary effects of trophy hunting should become more evident when population density is stable. Our data set was largely influenced by the rapid increase of mouflon density following the reintroduction, thereby limiting the possibility to detect the effects of trophy hunting. To clarify the consequences of commercial trophy hunting on mouflon it will be worth investigating the horn growth pattern over a longer timeframe, as well as the age-dependent siring success in males. These results would be of great importance for improving wildlife management practices.

density dependence, horn size, trophy hunting, ungulates, wildlife management

nije evidentirano