Comparison of visual bird migration counts with radar estimates. (31st March 2017)

• Record Type: Journal Article
• Authors: Schmidt, Matthias; Aschwanden, Janine; Liechti, Felix; Wichmann, Gábor; Nemeth, Erwin
• Is Part Of: Ibis. Volume 159:Number 3(2017:Jul.)
• Page Start: 491
• Page End: 497
• Publication Date: 2017-03-31
• Subjects: Alps -- Austria -- environmental impact assessment -- observation effort -- wind farms; Birds -- Periodicals; 598
• DOI: 10.1111/ibi.12473
• Languages: English
• ISSNs: 0019-1019

Abstract

Abstract : In the context of an extensive study on bird migration in the Austrian Alps, we compared data from a fixed‐beam radar with data collected by visual observation to estimate the intensity of migrating birds up to a height of 150 m above the ground. Migration traffic rates calculated from visual bird counts and radar measurements were strongly correlated. Using resampling techniques, we calculated a minimum observation effort for counting birds during a 5‐week period of peak migration. We chose ±20% of the real mean as the criterion for a reliable estimation. Our results showed that at least 19 observation days are necessary to assess the mean number of migrants passing within this low altitudinal range.