Montagu's harrier  (Circus pygargus)

The species was heavily persecuted in Britain during the 19th and early 20th centuries, and between 1850 and1920 no more than 7 pairs were recorded in any one year. The population then increased to 30 nests in 1953. The species was widely distributed at this time, with main population clusters in East Anglia and the South West. A further decline down to just 7 breeding pairs occurred between 1953 and 1962; this is thought to have been due to the widespread use of organochloride pesticides such as DDT at this time, which thinned eggshells and accumulated in the tissues of adult birds. No pairs at all were recorded between 1974 and 1975. Since then the population has fluctuated between two and eight breeding females. Montagu's harriers breed later in the season than marsh harriers, and as they nest amongst cereal crops, current threats to nests and young include toxic sprays and harvesting machinery. Predation by foxes may also cause losses, as does disturbance by birdwatchers, who are attracted by this beautiful bird's rarity (3).

No recent nesting site has been located within a protected area or Site of Special Scientific Interest (SSSI), however much of the former nesting grounds are now afforded protection. Nests on arable land must be located so that damage by farming practices can be avoided. Research is being carried out on the breeding biology, population dynamics and food of the species (3).