The willow warbler is the most common bird species in Finland. It is very modest looking, small and slender bird with greenish gray upper-parts and dirty light belly. Due to its modest appearance and its hidden lifestyle, the willow warbler is quite poorly known species and it is easily missed by the people enjoying the fresh air. The willow warbler feeds on insects and spiders.

The willow warbler is found in North and Central Europe and in Asia. The species winters in Africa and returns to Finland around May. As its habitat, the willow warbler qualifies all types of forests with even some deciduous trees and protective undergrowth. It can also live in the gardens and bushes in the yards. The willow warbler makes its oven-like nest on the ground using hays and mosses as building materials.