Impact of myxomatosis on densities of Iberian hares (Lepus granatensis) in North-western Spain: implications for management and sustainable hunting

Abstract

Outbreaks of myxomatosis in Iberian hares (Lepus granatensis) were detected for the first time in Spain in 2018. The disease spread to a significant proportion of the species range, negatively affecting the hare populations. In this study, we analyzed the impact of myxomatosis at hunting grounds of Castilla y León (Northern Spain), comparing hare density during two consecutive hunting seasons; the first when outbreaks were detected for the first time (season 1, Oct 2019-Jan 20) and the second after the spread of the disease (season 2, Oct 2020-Jan 21). Data was gathered from 1,102 hunts from 178 hunting grounds through “coursing”, a hunting type in which hunters and greyhounds search for hares, allowing the estimation of hare density. Overall, hare density decreased significantly, from 12.7 hare/100 ha in season 1 to 4.7 hare/100 ha in season 2. The percentage of hares suspected to be affected by myxomatosis (sick and dead) per hunt was higher in season 1 (14.4%) compared to season 2 (10.7%). For both seasons, this proportion was higher when hunting season was started (20.7%, October), compared to the remaining months (4.7%, November–January). However, the proportion of hunting grounds affected increased from 44% in season 1 to 66.7% in season 2. Our research confirmed a 62.7% reduction in hare density in Castilla y León after the spread of myxomatosis and identified scenarios of possible depletion when densities were below 4–5 hare/100 ha. As myxomatosis becoming endemic in Iberian hares is likely, hunters and game managers should continue current monitoring and disease surveillance and make management decisions accordingly.