Enhancing carcass removal trials at three wind energy facilities in Portugal

During the last years there has been a significant worldwide increase in the number of wind farms. This kind of energy can have negative impacts, such as the direct mortality or lethal injury of birds and bats caused by collision with wind turbines. In order to evaluate bird (or bat) mortality regarding wind power generation facilities, strict monitoring protocols are required which must take into account the possibility of carcass removal by scavenging animals or decomposition before the monitoring session. For this purpose, carcass removal trials with 180 carcasses representing three size classes (small, medium and large) were conducted in two seasons (Spring and Autumn) at three wind farms located in the central region of Portugal. No significant differences were found between removal rates of different wind farms or size classes contrarily to seasons, which presented an average carcass removal time of 3.9 and 4.6 days, respectively for Spring and Autumn. The results of the present study showed the importance of trials to estimate the carcass removal rates, which influences the survey effort management and consequently the monitoring protocols. The experimental design for future trials in the same region should account for season effect and be conducted using daily checks of the carcasses for, at least, 15 days.