Abstract
Very few data series are available on the long-term development of the bird fauna in northern Sweden. This kind of data is of great interest as there are recent signs that bird populations in northern Sweden are developing less favourable than in southern Sweden. We present trends in annual capture rates of 40 frequently ringed species at Stora Fjäderägg Bird Observatory, NE Sweden, autumns 1985–2014. Significant positive and negative trends were found in ten and eight species, respectively. Great tit, Chaffinch and Long-tailed Tit showed the strongest increases, whereas Northern Wheatear, Willow Tit and Bluethroat decreased the most. There was a significant negative trend in capture index for short-distance migrants and a positive trend for irruptive species/partial migrants. For many species, particularly those that were decreasing, the trends at Stora Fjäderägg are similar to population trends seen in Swedish and Finnish breeding bird surveys. For these species the trends at Stora Fjäderägg could be indicative of long-term population changes.
Highlights
Very few data series are available on the long-term devel opment of the bird fauna in northern Sweden
We present trends in annual capture rates of 40 frequently ringed species at Stora Fjäderägg Bird Observatory, NE Sweden, autumns 1985–2014
These trends are compared with population trends for breeding bird surveys from Sweden and Finland for the same time period
Summary
Very few data series are available on the long-term devel opment of the bird fauna in northern Sweden. Those that were decreasing, the trends at Stora Fjäderägg are similar to population trends seen in Swedish and Finnish breed ing bird surveys. Svensk Få geltaxering (SFT) kommer med tiden att svara upp mot detta behov, men standardrutterna – den mest tillförlitliga datakällan – har inte varit i funktionell drift längre än dryga tio år i norra Sverige (Green & Lindström 2015a). Analys av återfynd av fåglar ringmärkta på Stora Fjäderäggs fågelstation i nordöstra Sverige antyder att våra nordliga och sydliga fågelstationer berörs av olika flyttfågelflöden Vi har ingen entydig bild av vari från fåglarna som fångas på Stora Fjäderägg kom mer; kontroller av fåglar ringmärkta tidigare sam ma höst indikerar dock ett betydande inflöde från ost och sydost Under åren fällan var i drift var ett par nätplatser avvecklade och utnyttjandet av fällan gav inte några uppenbara effekter på fångsten (Figur 1)
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