- The birds signal if there is something in the environment that is not right, says bird researcher Martin Green from Lund University.
Forest-dwelling birds such as the lesser woodpecker, lap tit and pine tit are becoming fewer and fewer, according to the environmental monitoring program Swedish Bird Taxation.
At the same time, the prevalence of finch, blue tit and black cap is increasing.
These are birds that are not so careful and can change food depending on availability.
- For specialized forest birds, we see a worse development.
We believe this is partly due to the fact that we have recently reshaped the forest, says bird researcher Martin Green.
Denser forests with monocultures have changed the habitats of many species, and this affects the birds that are dependent on natural forest.
- The way we cultivate forests today means that we do not get any variation.
We have large areas with the same tree species of the same age.
It provides poor conditions for a richer biodiversity, says Martin Green.
Watch the entire World of Science "The Battle for the Forest - Sweden's Last Forests" on Monday 20 September at 20.00 on SVT2 or on SVT play from Sunday 19/9.