Marsh harriers recovered from near-extinction in the UK, with only one breeding pair in 1971, to over 400 pairs today, following DDT bans and reedbed restoration. Their welfare remains dependent on continued wetland management.
Marsh harrier welfare was historically catastrophic due to organochlorine pesticide-induced reproductive failure — a classic case of chemical contamination disrupting entire populations. The recovery demonstrates that welfare harms from widespread chemical use can be reversed when the cause is addressed. Current welfare considerations include reedbed management that maintains suitable nesting conditions and territorial establishment for recovering populations.