TY - RPRT
TI - Avian post-construction studies and EIA for planned ex-tension of the Hitra wind-power plant
AU - Bevanger, K
AU - Dahl, E
AU - Gjershaug, J
AU - Halley, D
AU - Hanssen, F
AU - Nygård, T
AU - Pearson, M
AU - Pedersen, H
AU - Reitan, O
AB - Ornitologisk etterundersøkelse og konsekvensutredning i tilknytning til planer for utvidelse av Hitra vind-kraftverk (Avian post-construction studies and EIA for planned ex-tension of the Hitra wind-power plant) is only available in Norwegian. However, the report's conclusions are available in English below.Searches for dead birds:Searches for dead birds, assisted by a dog, have been carried out during the period with no snow cover in 2009; once a week from April to November (last time in week 47), ex-cept June 15 – August 1 and in October-November when the searches were carried out every second week; in total 24 weeks. A total of three white-tailed eagle and seven willow ptarmigan carcases were recorded. In addition, a total of five white-tailed eagles have been found apparently killed by collisions with the existing wind-power turbines since summer 2006; one in 2006, one in 2007 (or 2006), three in 2008 and none in 2009, by power plant staff or the general public although no systematic searches were made. This gives an average of approximately 0.06 dead white-tailed eagles per turbine per year, slightly less than on Smøla (approximately 0.1 dead white-tailed eagles per turbine per year). The dead willow ptarmigans recorded give an average of 0.17 per turbine per year, almost the same as the Smøla average for three years (0.15). The results indicate that the annual number of dead birds recorded varies, and that an annual average probably is slightly less than two dead white-tailed eagles and four willow ptarmigans as long as 24 turbines are operating in the wind-power plant.The number of dead birds recorded is minimum figures. The total collision rate has not been estimated, however, the terrain where the power plant is located is difficult to search, and thus the habitat bias will be significant. Taking into account removal rate (scavenging bias) and search efficiency of the dog (search bias) it is assumed that the real number of casualties is somewhat higher. Dead birds are particularly found near turbines located at the edge of the power plant.There is insufficient evidence to conclude whether the recorded mortality for the white-tailed eagle is or is not acceptable with regard to short- or long-term population develop-ment. As regards the willow ptarmigan population, the data, while not conclusive, in com-bination with population censuses suggests that the power-plant extension will not be un-acceptable for population development. Both for the white-tailed eagle and the willow ptarmigan an increased mortality must be expected when the power plant turbine number is increased.White-tailed eagle, golden eagle and goshawk:For the white-tailed eagle an increased collision risk and casualty numbers caused by an increase in turbine numbers is expected. Two breeding territories will be located within 1.5km of the turbines following the power-plant extension, and a lowered breeding suc-cess may result. Two juvenile white-tailed eagles and one juvenile golden eagle that were tagged with satellite transmitters during the summer of 2009 had not used Eldsfjellet by February 1, but it is premature to draw conclusions on juvenile eagles’ use of the area given the limited number of birds and the short time series.The existing data are insufficient to conclude whether the encroachments connected to an extension of the power plant are unacceptable or not with regard to short- and long-term white-tailed eagle population development. For golden eagle and goshawk the conflict level is not expected to increase as a result of an extension of the existing wind-power plant, except through a general increased risk for all species due to the increased number of turbines.Eagle owl: It is important to clarify whether there are established breeding pairs within the planning area, particularly in connection to the planned road access from the south. By building this road a general disturbance increase will take place. Whether the routing of the road will conflict with nest sites of red-listed species like the eagle owl and grey-headed wood-pecker is unknown as the routing not was known when the fieldwork took place during spring/summer 2009. There is, however, more reason to believe that the road might threaten an eagle owl territory than the contrary.The existing data are insufficient to conclude whether the encroachments connected to the road building from the south into the power-plant area are acceptable/unacceptable with regard to short- and long-term population development and survival for the eagle owl. Apart from this, construction of the Hitra 2 wind power plant is not considered to be unac-ceptable for the eagle owl, however, it cannot be ruled out that eagle owls will be killed by colliding with the power lines and/or turbines that will be constructed.Breeding small birds and waders:Recorded data on breeding small birds (mainly passerines) indicate a rather negligible impact of an extension of the power plant on the Eldsfjell plateau. Within areas situated below the plateau, like Ramnåsheia, potential negative impacts from an extension are somewhat higher, because of the more diverse and abundant bird fauna. Grey-headed woodpecker (red listed) is a resident species of these areas. The other species known to be present, however, are quite common.The existing data are insufficient to conclude whether the encroachments connected to an extension of the power plant are unacceptable or not with regard to short- and long-term grey-headed woodpecker population development. For the other species observed in the area, the probability of unacceptable negative effects of a wind-power plant extension is low.Willow ptarmigan and tetraonids:Censuses conducted in 2009 indicate no population differences between Eldsfjellet and Skårfjellet; neither do data collected earlier (2007-2008). Although there is no pre-construction data from these areas, the overall habitat quality of the areas seems quite similar. This suggests the wind power plant has not had a significant impact on the willow ptarmigan population at Eldsfjellet. It is likely that an extension of the plant will not have a significant additional impact. Only minor habitat areas suitable for tetraonids (black grouse and capercaillie) are found on and near Eldsfjellet. Tetraonids were neither observed dur-ing the August nor October censuses. In the Skårfjellet/Mørkedalstua areas the habitats are more suitable and two black grouse were observed. The data are insufficient for evaluating tetraonid impacts from an extension of the wind-power plant in the area. How-ever, it seems likely that an extension only will have a minor impact.Based on the willow ptarmigan censuses carried out it is likely that the planned wind-power plant extension will not be unacceptable with regard to population development. This conclusion is, however, not very firm. Based on tetraonid observations, the wind-power plant extension does not seems to be unacceptable for those species, however, it cannot be ruled out that some specimens will be killed by colliding with the power lines.Power line:The final routing plans for the power line seems to generate moderate conflicts with re-spect to bird collisions; however a prerequisite is that the line follows depressions in the terrain lowering the wires to a height below the treetops in forested areas. This is impor-tant with regard to collision hazard, as the tree canopy frequently determines the lower limit for bird flight height. One of the final plan drafts indicates a routing of the power line high up in the terrain, making it particularly exposed in the area from the southernmost turbines and transformer towards the central part of the power plant. Here the collision risk for grouse species as well as raptors and other species will be high. The alternative rout-ing lower into the valley should be preferred.Terrain modelling:Areas where the terrain topography, together with solar radiation and prevailing wind di-rections, generate upward air currents (ridge-wind) are identified. Steep slopes towards the south are easily warmed by the sun and create potential areas for ridge wind/thermals. These are frequently used by white-tailed eagles and other raptors to gain height. Locat-ing wind turbines, power lines or other man-made air obstacles in such areas, where fre-quent hang-wind/thermal generation takes place, may create an increased risk for bird collisions or injuries. Based on SpacEyes viewer, the user will be able to navigate within the terrain model and view the landscape and the turbine locations from a ”birds perspec-tive” (own DVD attached).The final draft plan for the turbine locations indicates planned locations in areas where ridge winds are generated and thus an increased collision hazard for white-tailed eagles.Mitigating measures:An important mitigating measure regarding white-tailed eagle and golden eagle for a Hitra 2 wind power-plant is to avoid wind-turbine locations on the ridge of south sloping cliffs, i.e. areas where thermals and hang winds are easily generated. Roads and turbines close to nesting areas for eagle owls and grey-headed woodpeckers should be avoided. The present data is, however, insufficient to conclude whether the planned road into the pow-er-plant area from the south will conflict with such nesting areas. The potential conflict due to red-listed bird species collision risk with a new power line to the south can be eliminat-ed by using a buried cable. However, if over-head wires are used it should follow depres-sions in the terrain and lowering the wires to a height below the treetops in forested areas. For more general discussions on possible mitigating measures, the annual reports from the research conducted on Smøla should be read.Prediction assessments of the EIA report from 1999:In connection with plans for a wind-power plant on Hitra, NINA made a consequence as-sessment (NINA Oppdragsmelding 625) with regard to Norwegian red-listed bird species in the area. The report was primarily based on the limited existing knowledge, supple-mented with some new field surveys. The following conclusion was reached: “The avail-able data are very scanty, making predictions and assessments difficult. Red-listed spe-cies generally are low in numbers, and therefore require thorough surveys. Lack of ex-perience with wind power plants in Norway makes predictions of possible effects difficult. The most probable impacts of a wind power plant are related to loss and fragmentation of habitat, and reduced habitat quality in a wide belt around the developed area. An addi-tional aspect is the collision risk with turbines and power-lines, and the disturbance effect from turbines, construction activities, maintenance work and traffic by people. There is a high need for follow-up studies, in order to elucidate mitigating measures”.Prediction assessments of the EIA report from 2003 (NINA Notat):In November 2002 NINA was contacted by Statkraft SF, based on the No 7 conditions re-garding ”mapping of birds” given by the NVE license given to Statkraft SF December 20 2000: "To increase the basis for possible recordings of impact on birds the license appli-cant should conduct a survey of the birdlife before the construction work is initiated. … Furthermore the license applicant should make a plan for a follow-up registration. The plan should be presented for – and approved – by NVE before the power plant is put into operation." The field work made during the 2003 breeding season was conducted before any encroachments were undertaken, and the conclusions were that: The results confirm, for several species, what earlier registrations on Hitra has confirmed regarding density and abundance of nest sites and breeding pairs. Several new records were also made, confirming that it is difficult to locate all nesting pairs and nest sites. - - A majority of the fo-rested area surrounding Eldsfjellet has a character of virgin forest. This is also reflected in the species composition; with e.g. a dense grey-headed woodpecker population as well as a frequent occurrence of redstart. A construction road into the wind-power plant area makes the areas easily accessible for human activity, including logging. A road will also facilitate other disturbances and impacts than those directly related to the wind-power plant and the power lines. Several of the located nesting sites of red-listed species will have problems to sustain as such in the years to come. If these are to be maintained, a protection regime of the adjacent areas to the nests is necessary, including strong regula-tion of the general traffic in the area”.The assessments made in the 1999 and 2003 NINA reports made in connection to the Hitra 1 Wind Power Plant in general are in line with the conclusions in the present report.
DA - 2010/03//
PY - 2010
SP - 68
PB - Norwegian Institute for Nature Research (NINA)
SN - NINA Report 503
LA - English
KW - Wind Energy
KW - Land-Based Wind
KW - Collision
KW - Birds
ER -