>> Background information

Development

Forest generalist birds occur in a wide range of wooded habitats. A common characteristics to all species in the group is that they thrive in commercial forest, which are normally treated with regeneration fellings at the age of 60-120 years. Altogether 20 species were included in the indicator. Their populations have increased on average by 10% during the monitoring period, which started in 1979. Forest generalists have been particularly abundant in recent years. The group accounts for more than half of all breeding bird pairs in the country.

Most of the 18 coniferous forest species prefer spruce forests as breeding habitats. In this regard the group could also be called spruce forest birds. The group includes some old-growth forest species, but most of the species thrive also in younger stands. On average, the populations of coniferous forest species increased by almost 20% during 1979-2008. Abundant pine and spruce seed yield years 1990-1992 and 2001 can be seen as temporary peaks in the indicator. The species in the group have become more abundant as the growing stock of Finnish forests has increased.

Of all the species included in the two indicators local residents and short-distance migrants have fared clearly better than long-distance migrants. The populations of the former increased by 40% while long-distance migrants decreased by one fifth during 1979-2008.

Forest long-distance migrants include, for example, two steeply decreased species, Eurasian Wryneck and Tree Pipit. The underlying causes of their declines are poorly known. Many of the forest bird that overwinter in Fennoscandia have benefitted from feeding and mild winters. Great Spotted Woodpecker, Common Blackbird, Eurasian Bullfinch and Eurasian Jay are such species.

Forest generalists

Several forest generalist species accept small wooded patches or even a groups individuals trees as their breeding habitat. Some of the species in this group benefit from the structural changes such as fragmentation and the increase of bushy edge biotopes that are brought about by commercial forestry practices. These species include Willow Warbler and Tree pipit, the most and fifth most common bird species in the country.

In addition to Great Spotted Woodpecker and Common Blackbird, species that migrate only short distances if at all, the list of increased forest generalists includes Winter Wren, Trush Nightingale and Pied Flycather. Winter Wren has adopted to new biotopes such as the edges of clear felled areas besides it original habitat in old-growth forests. Trush Nightingale has most probably befenitted from a warmer climate whereas the reasons behind the increase Pied Flycather are unknown. Forests generalists includes the most steeply fluctuating species in Finland, Common Redpoll. The population of Common Redpoll reflects the amount of seeds of deciduous trees available during winter.

A number of forestry related reasons are likely to be found behind the positive development of forest generalist birds. Finnish forests are clearly younger now than in the 1950s. Clear fellings and the draining of mires, for example, have created a great number of young forests that are often dominated by deciduous trees. These habitats are most suitable for species like Willow Warbler and Redwing.

Coniferous forest species

In addition to species of spruce forests, only two species associated with pine-dominated forests have been included in this group. These are Mistle Trush and Common Redstart. Crested Tit may, for its part, be considered as a coniferous forest generalist. The four most common coniferous forest birds are European Robin (1.7 million pairs), Eurasian Siskin (1.6 million), Coldcrest (1.2 million) and Common Redstart (0.8 million).

The group includes 15 species that over-winter in Europe and only two that migrate to sub-Saharan Africa: Common Redstart and Common Chiffchaff. The population of Redstart has increased in northern Finland. Chiffchaff seems to have partly recovered from its dramatic decline by the early 2000s.

Three species belonging to the group benefit from feeding during winter. The populations of Bullfinch and Eurasian Jay have increased whereas Willow Tit has declined despite the availability of supplementary food during winter. The abundance of Siskin and Crossbills fluctuate steeply according to Norway Spruce seed harvest. The seed yield of both pine and spruce as well as winter weather conditions have a great impact also on other coniferous forest species. Coldcrest, Tits, Eurasian Treecreeper and Bullfinch are such species.