Portugal's bat population is declining in areas with high concentrations of turbines, according to Francisco Amorim, a Portuguese environmentalist who says he has evidence to back his claim. Amorim has been monitoring the areas of Arada and S. Macáro in the regions of Aveiro and Viseu, which respectively host 42 MW and 415 MW of wind farms. Bats are protected by law in Portugal. Increased bat mortality has been detected in many of the monitored wind projects, reports Amorim, with peaks at the end of summer and the start of autumn. Although the causes are unknown, Amorim has a theory: "The sounds produced by the turbines may be attracting or disorienting the bats. These mammals also have some difficulty in detecting moving blades." Among potential solutions, Amorim proposes "the promotion of feeding habitats and artificial shelters." Although an environmental impact evaluation is required for wind plant, its recommendations are only obligatory when turbines are installed in protected areas or more than ten units are involved.