We all know that juvenile Blackcaps have nice auburn heads like their mothers, but in fact there seems to be quite a lot of variation. When you've spent the morning ringing ginger mingers like this one ...
... it can come as a bit of a surprise when you come across one like this ...
A recently fledged individual but it only has the extreme tips of its crown feathers fringed with brown, a more than usually decurved bill, and is generally more 'chunky'. This caused a certain amount of head-scratching at the time, but fortunately a wiser head was quickly on hand to restore order.