Progressive impact of piecemeal infrastructure development on wild reindeer

We made monthly surveys of >2000 reindeer (Rangifer tarandus tarandus) from 1977 to 1987 before and after the construction of the Blue Lake hydroelectric reservoir in order to study the progressive impact of infrastructure development on wildlife. Following this development, reindeer densities within a 4-km radius declined gradually during winter to 8% of pre-development densities without significant changes in undeveloped control sites. During summer, reindeer gradually reduced use of areas within 4 km distance from roads and power lines to 36% of predevelopment density, with subsequent 217% increase in use of the few remaining sites located >4 km from infrastructure. Reindeer reproduction declined progressively as habitat was lost. Assessments of individual development projects seriously underestimate the long-term effects of the entire expanding infrastructure network. Piecemeal development has resulted in an estimated 70% loss of undisturbed reindeer habitat across the last century in Norway. During this time the reindeer population has become fragmented into 26 isolated sub-populations. Our results show that any further infrastructure development will put the remaining European population of wild mountain reindeer at great risk, as further habitat fragmentation will make the remaining undisturbed patches too small for holding viable populations. A general model of impacts of infrastructure on wildlife is presented. We discuss the importance of controlling piecemeal development in infrastructure for conservation of wildlife and argue that minimizing infrastructure development is likely one of the largest challenges in wildlife conservation ahead.