I have enjoyed watching a pair of Willow Warblers this week. They are nesting close to a path and high up in a bank but very close to the ground.  The tiny nest is really well concealed and it has to be because predation is very common and a large percentage of nests fail.  For this reason the young grow rapidly and fledge the nest at around 11 to 12 days old. They work really hard to feed their clutch and are constantly collecting prey and will deliver to the nest around 10 times an hour.