Searches for dead birds in Smøla wind-power plant area 2011 - annual report


Title: Searches for dead birds in Smøla wind-power plant area 2011 - annual report
Authors: Reitan, O.
Publication Date:
January 01, 2012
Document Number: NINA Report 790
Pages: 28

Document Access

Website: External Link
Attachment: Access File
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Reitan, O. (2012). Searches for dead birds in Smøla wind-power plant area 2011 - annual report. Report by Norwegian Institute for Nature Research (NINA). pp 28.

(The majority of the report is in Norwegian. However, there is an abstract in English.)


This report describes the searches for dead birds in the Smøla wind-power plant area (SWPPA) in 2011, and compares the results of the dead birds found with 2006-2010.


The search effort in 2006-2010 was systematic, as the same method and procedures were followed, with the same effort each week throughout each year. The results of dead birds found could thus be compared between years, seasons, months, and the different parts of the wind-power plant and single turbines. The data could be used to calculate averages found each year, and also now making it possible to estimate total numbers annually colliding with turbines for several species. These data are therefore a good basis for comparing result for later years.


To search for dead birds, localize and recording wind turbine victims are the first steps towards estimating real collision numbers in a wind-power plant area. In addition, there are several biases affecting the proportion of dead birds available for searches. Several methods may be used, among them different approaches using dogs. In the SWPPA a feather search dog was used, to search, find and indicate feathers and other remains from dead birds. In 2006-2010 two dogs were used in SWPPA, both with god search qualities. In 2011 the best of these dogs, the giant schnauzer Luna, was used on all turbine searches. The search motivation of Luna has been very good in nearly all searches in 2011. The search results from SWPPA therefore are as reliable as possible today.


In 2011 searches were carried out at all turbines five times, three in spring (5-7 April, 29 April – 1 May, 26-28 May) and two in autumn (12-15 September, 21-22 November). In April–May a total of 203 turbine searches were performed. In each of the previous years, the total numbers of turbine searches in the spring (March-15 June) varied between 359 and 473. In autumn 2011 a total of 136 turbine searches were performed, about 60% of each of the previous years in the months September-November. At the searches in 2011 all 68 turbines were searched in three days. The field work routines in 2011 were identical as in 2006-2010, both during each search day, at each turbine, and when a dead bird was found. Each dead bird discovered was collected as complete as possible, and autopsy was carried out later. All dead eagles were reported to Statkraft on the day of discovery.


In total 12 dead birds were found beneath wind turbines in the five searches in 2011, 10 in March-May, and two in September and November. In addition, three birds were found. Four dead white-tailed eagles were found, at four turbines. Two were found as collision victims in April, and two were victims in August-September. One eagle was 8 years old, one was 2 years, the other two undetermined (one adult and one young bird). Besides the eagles, six other species were recorded; three willow ptarmigans, three hooded crows, two northern wheatears, and one of each of grey lag goose, golden plover, and redpoll. All except one eagle had been lying there at a maximum of three weeks before the discovery.


Few dead birds were found in the SWPPA in 2011 compared with 2006-2011 , both for the year in total and for the spring period. The data in 2011 indicate a much higher rate of disappearing of dead birds in the SWPPA than assumed in the BirdWind report (Bevanger et al. 2011). The numbers of discovered dead birds therefore seem to be dependent on the total search effort in each year, and a high search effort especially in the vulnerable period in spring is necessary to increase the reliability of the results. Good routines are necessary in all discoveries of dead eagles and other vulnerable species.


Norwegian Title: Søk etter døde fugler i Smøla vindpark 2011 - årsrapport

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