The breeding population of Red-flanked Bluetail in Finland has risen spectacularly in recent years, with the latest Finnish nesting-bird report estimating there to be 13,000 breeding pairs for the 2019-2024 period.

This tally is a significant increase on the estimated 1,500 pairs in the period of 2013-2018. In 2021, a minimum of 1,230 singing males were recorded across the east and north-east of the country alone.

Finland represents the western edge of this species’ range. The charismatic species breeds in the moist, old-growth taiga forest, often on sloping ground rich in moss and standing deadwood.



Finland’s breeding population of Red-flanked Bluetail has boomed in recent years (Marc Fasol).

 

Booming bluetails

Although the first nesting records in Finland date from 1971 near Kuusamo, the species remained rare for many decades with only a handful of territorial males observed each breeding season.

Populations have fluctuated strongly year to year: for example, estimates of singing territorial males in eastern and north-eastern Finland have ranged from more than 400 in 2010 and 580 in 2012, to dips below 300 in other years.

Despite this variability, the upward trend is clear, even if the species remains classified as Vulnerable in Finland due to its concentration in specific areas such as Kuusamo, Kuhmo and elsewhere in the east and north-east.

 

Expansion linked to climate

The changes are thought to be linked in part to an expansion westward of suitable habitat, possibly driven by a warming climate. Exceptional spring warmth in past years has been noted as a factor coinciding with earlier expansion waves. 

However, it is not yet certain whether all habitat changes will favour the species in the long term. 

In addition, other taiga species show mixed trends, as per Ornithomedia. White-backed Woodpecker has increased from roughly 230 pairs to 500, while species such as Siberian Tit have suffered marked declines.

In the October 2025 issue of Birdwatch, David Campbell explores the rise of Red-flanked Bluetail in Britain and Europe.