Data from: Study "Reindeer movement in East Iceland"
2022-04-07, Ágústsdóttir, Kristín, Þórisson, Skarphéðinn G.
Reindeer live wild in the East of Iceland. Their numbers and spread have increased since 1940. Throughout most of that period, the Snæfells herd has been the most important herd. In 2003 construction to prepare the largest hydro power plant in Iceland was started in the middle of an important summer and calving area. From 2002, the East Iceland Nature Research Center has monitored the impact of the construction of the Kárahnjúkar power plant on the Snæfells herd. During the construction period, the physical condition of the animals was generally good due to mild winters. Direct effects of the project on the animals included the inundation of natural pastures and the destruction of others due to the development of new infrastructures. The main indirect effect was likely the increase in road kills as more reindeer were hit by cars due to traffic in previously pristine areas. However, the distribution of animals changed on both sides of Háls (the area where Hálslón reservoir was created in 2006), even before its construction started. In 2002, the main summer pastures of Snæfellsherd moved from Vesturöræfi just east of Háls to Fljótsdalsheiði further east. The number of animals in Fljótsdalsheiði increased until 2009, but in 2011 and 2013 there were fewer animal in the Snæfells herd than had been seen for five decades. This was mainly due to increased hunting and a change in the distribution, as the animals seemed to have moved from the classical Snæfellsherd areas to adjacent areas. In Kringilsárrani (west of Háls) the males disappeared from 2006, just before the main construction started in Háls. The number of animals there also fluctuated during the construction period. In Vesturöræfi, we observed an increase in vegetation productivity, alongside a diminution in sheep density and an increase in the abundance of pink-footed geese during the construction period. Changes in the abundance and distribution of the Snæfells herd after 2000 are likely linked to changes in weather conditions, the cumulative long-term effects of the power plant construction and disturbance, and the increased flow of tourists into the previously pristine area. Research with 8 GPS collared female reindeer in Snæfellsherd from 2009-2011 revealed a significant difference in travel behaviour and home range size according to the seasons of the year. The average size of the total home range for the different herds was 949 km^2 with the largest home range at 1,424 km^2. The largest home range for an individual cow was 1,558 km^2. Home ranges were generally smaller during the breeding season and larger during the hunting season. There was a strong positive relationship between the seasonal running speed of reindeer and the home range sizes. Moreover, animals ran significantly faster when the ambient temperature was high. There were no obvious correlations with other climatic variables. The different sub-herds of the Snæfells herd grazed in different areas. The herd belonging to hunting area 1 most commonly grazed in sparsely vegetated areas and dwarf willow scrub, while the herd belonging to hunting area 2 most commonly used dry sedge heath and sedge fens. Reindeer with GPS collars seemed to avoid cabins, but other human infrastructures appeared to have little effect on their movement. During the hunting season, they travelled faster when in proximity to roads, trails, and cabins. It was not possible to identify obvious deterrent effects of the construction of Kárahnjúkar power plant on reindeer movements in Snæfellsöræfi, as no animals were tagged with GPS prior to the construction of the power plant.