In the severe winter of 1962/63 the Dartford warbler (Sylvia undata) was almost wiped out in Britain. The national population dropped to just 10 pairs.
But in good breeding seasons, and with suitable habitat, its numbers are capable of bouncing back, thanks to repeated nesting and high survival rates among its offspring.
On the Surrey lowland heaths Dartfords have been doing well, re-colonising Thursley Common last year for the first time since a devastating fire in 2006.
During the recent freezing winter weather I photographed this Dartford warbler foraging in the snow on Chobham Common: