Transmission line areas provide a favourable nesting environment for wood larks and red-backed shrikes

Research by Pertti Koskimies completed: "Transmission line areas provide a favourable nesting environment for many bird species which prefer low bushes and half-open terrain." This is stated by Pertti Koskimies, ornithologist and Licentiate in Philosophy, in his research report of birds nesting in transmission line areas in Southern Finland.Pertti Koskimies studied bird species nesting in transmission line areas in Southern Finland in 2002 to 2003. The total area covered by the research was 370 hectares. The areas selected for the research represented samples with varying widths and environmental features in typical transmission line areas in Southern Finland. The counting areas were located in Siuntio, Porvoo, Pernaja, Miehikkälä, Hamina, Luumäki and Kokemäki. The purpose of the research commissioned by Fingrid Oyj, which is responsible for the main electricity transmission grid in Finland, was to ascertain:
- what bird species nest in transmission line areas in Southern Finland and how many such birds there are
- what is the significance of transmission line areas as a habitat of endangered bird species, ones with significant protection value, and rare bird species
- how does the clearing of the transmission line area affect the diversity of bird species and number of birds
- how should clearing be developed so that the populations of protected nesting birds in particular are not endangered by clearing. A total of 53 bird species nested in the researched areas. Most of these species are common birds in forests and bushes. Transmission line areas turned out to be an important habitat for the red-backed shrike, wood lark, whitethroat, lesser whitethroat, garden warbler, robin and yellowhammer. The research indicated that the nesting frequency of these species in transmission line areas is considerably higher than in other Finnish habitats on average. The most valuable species in transmission lines in terms of protection value are the red-backed shrike and wood lark, which are included in species requiring special protection, listed in appendix I of the bird directive of the European Union. "A significant portion of the total populations of these species nest in transmission line areas," says Pertti Koskimies. The trees and bushes in transmission line areas are cleared at intervals of about 5 to 7 years. The clearing interval has been shortened in some locations because of results obtained from earlier studies (such as a study by the Finnish Environment Institute on the significance of transmission line areas on meadow plants and butterflies, published in 2003), because transmission line areas are vital compensatory habitats for species which have suffered on account of the disappearance of natural meadows. According to the findings of the current study, many bird species disappear from transmission line areas during the year following clearing because there are no small trees or bushes, but these species return in these areas quickly in line with the emergence of new saplings. According to Pertti Koskimies, newly-cleared open terrain is occasionally used as a feeding place by species which do not prefer thick bushes that are created towards the end of the clearing cycle. In this way, transmission line areas offer a suitable habitat for dozens of bird species during the entire clearing cycle. Ari Levula, Maintenance Manager for Fingrid's transmission lines, says that the results of the current research confirm the notion of the purposefulness of quicker clearing cycles from the viewpoint of nature conservation. "In accordance with our clearing instructions, we already save trees such as junipers, which are important nesting and viewing places for the red-backed shrike. We have established specially-managed butterfly meadows in transmission line areas in Southern Finland, and we are using these sites to also test whether the piling of clearing waste offers tempting and safe nesting places for the red-backed shrike." According to Ari Levula, bird species nesting in transmission line areas are taken into account in the use of clearing methods and scheduling of clearing. Areas with much juniper, which are known to be significant nesting areas, are cleared manually, and mechanical clearing is avoided during the early summer. Further information:
Pertti Koskimies, tel. + 358 (0)40 721 6764
Ari Levula, tel. + 358 (0)30 395 5505, + 358 (0)400 648 522