Birds tend to establish their territories and attract mates either through song or appearance. It is rare for a bird to be brightly coloured and have a good voice.
Look at the finch family, for example, here we have a group of birds in which the male has a beautiful plumage. Bullfinch, chaffinch and greenfinch are all classic examples of birds who attract their mates using colour rather than song.
The problem with their strategy is that they have to sit somewhere they can be seen in order to show off their fine plumage and this means they are in danger from sparrowhawks. At the other extreme we have warblers, birds which usually look very drab and often skulk in the middle of dense shrubs. Instead of using plumage to attract mates they use their song. Not all of their songs are necessarily attractive to our ears but they are all loud.
One of the plainest of all warblers, the garden warbler, can be seen in gardens during the summer. It is difficult for me to pick out any key identification features of a garden warbler's plumage, it is just brown. It is slightly darker on the back than on the belly and if you look very closely, and from the right angle, you might just spot a greyish-brown patch on the side of the neck.
You might think it isn't worth getting excited about a garden warbler, but I always do! The garden warbler has a beautiful voice, not unlike that of the blackcap. To distinguish between the two is a challenge, one which I think is worth the effort partly because the garden warbler is much less common than the blackcap. I always listen very carefully to every warbler in the hope of finding a garden warbler whose song is slightly more thrush-like with a harsher edge to it than the more fluty-sounding blackcap.
Blackcaps can live in any thickets whereas garden warblers like to have a few tall trees close by, hence they like mature, semi-wooded gardens. They can be seen throughout England, Wales and southern Scotland from May to September.