How do migratory species add ecosystem service value to wilderness? Calculating the spatial subsidies provided by protected areas

Species that migrate through protected and wilderness areas and utilize their resources, deliver ecosystem services to people in faraway locations. The mismatch between the areas that most support a species and those areas where the species provides most benefits to society can lead to underestimation of the true value of protected areas such as wilderness. We present a method to communicate the “off-site” value of wilderness and protected areas in providing habitat to migratory species that, in turn, provide benefits to people in distant locations. Using northern pintail ducks (Anas acuta) as an example, the article provides a method to estimate the amount of subsidy – the value of the ecosystem services provided by a migratory species in one area versus the cost to support the species and its habitat elsewhere.