The wood warbler is a passerine that is not so well known, even though it has greatly increased in the Royal National City Park over recent decades. Green, white and yellow nuances in its coat distinguish it from its close relative the willow warbler – Sweden’s most common bird – which it otherwise resembles. One would expect this unobtrusive bird to be hard to spot. However, its territorial call is very distinct. It is an accelerating silvery trill, which the bird-books usually compare to a coin spinning on a table (preferably marble-topped). As the bird calls, it flies hither and thither within the forest with a slow gliding flight and is therefore easy to observe. It often sits on a branch singing with upturned beak and vibrating body. The wood warbler can be found all over the park in the natural mixed forests; a sure spot is the path around Isbladskärret and northeast of Lappskärret.