Reindeer fidelity to high quality winter pastures outcompete power line barrier effects

Abstract

We investigated barrier effects of a 66 kV power line established in 1966 before and after the line was upgraded to 132 kV in 2004 over a period of 44 years (1974-2017) in the North Ottadalen wild reindeer area (3245 km2) of which 1038 km2 are in use as winter pastures. The power line transects a peninsula (135 km2) with high quality winter pastures in the southeast periphery. The reindeer population originated from a nucleus herd of 402 animals of domestic origin released in the area in 1964-1965 and 100 resident wild animals. Yearly winter survey started in 1974 and reindeer were first surveyed south of the 66 kV power line in 1982. Comparing the number of animals recorded in the peninsula vs. the number of individuals expected relative to available grazing area during the three periods (1974-2004, 1982-2004 and 2005-2017), the number of animals recorded in the peninsula was 3.6–4.9 times higher than expected. Since the upgrade of the power line, a substantial part of the reindeer population grazed in the peninsula every year. We therefore conclude that there was no long-term barrier effect from the original power line and no barrier effects at all from the upgrade. However, during the first 5 surveys of this study, there were no animals in the peninsula. Therefore, even if there are several possible reasons for this, we cannot exclude the possibility of short-term barrier effects resulting from the construction of the original power line. Our results support recent studies that report no effects from existing power lines and contrast some previous findings that have reported strong long-term barrier and avoidance effects of such infrastructure for Rangifer migration and grazing behaviour.

Biodiversity on the line: life cycle impact assessment of power lines on birds and mammals in Norway

“…Power lines may not pose a barrier for ungulates [105,106], but linear clearings can negatively affect ungulate populations due to habitat change and increased predation [107,108]. Although larger mammals are often more affected by habitat loss and fragmentation [50,97,109,110], several studies show that carnivores are attracted to linear clearings and select them for their travel patterns [102,104,111].…”

“…Finally, our models only address the operational phase, but the construction phase may induce short-term disturbance for species such as reindeer (Rangifer tarandus) [106,119].…”

Maps and stories in the creation of richer accounts of change in pastoral landscapes in Nordland, northern Norway

“…Research has documented direct, indirect and cumulative effects of land-use changes that encroach on herding routes. Encroachments have direct effects by removing the pasture itself for infrastructures such as mines, windmills, power plants, roads and railway; indirect effects where reindeer react to such infrastructure or human presence by avoiding movement or activity such as calving or feeding (Skarin et al 2015(Skarin et al , 2018Reimers et al 2020); and cumulative effects where multiple direct and indirect effects amplify the impact of each individual presence (Riseth and Johansen 2019). Direct effects with encroachments in nature landscapes often lead to physical loss of land and disturbance of both reindeer and other ungulates.…”

“…Direct effects with encroachments in nature landscapes often lead to physical loss of land and disturbance of both reindeer and other ungulates. Studies show that direct disturbance affects reindeer, that reindeer avoid areas where wind turbines are in sight and that new wind farms also may change reindeer selection of calving sites (Skarin et al 2015(Skarin et al , 2018Reimers et al 2020).…”