Rare species such as marsh harriers, ravens, buzzards, storks and stone curlews
had also shown increases, probably due to conservation efforts.
The bodies of eight stone curlews
, a threatened species which migrates from wintering grounds in Africa and Spain in the spring, have been found in fields in Wiltshire, Norfolk and Suffolk in the past few days.
Diurnal and nocturnal ranging behaviour of Stone Curlews
Burhinus oedicnemus nesting in river habitat.
It also pointed out that some species of farmland birds, including cirl buntings, stone curlews
, goldfinch and whitethroat, have increased.
Results were compared with values from studies done in houbara bustards (Chlamydotis undulata), kori bustards (Ardeotis kori), stone curlews
(Burhinus oedicnemus), and taxonomically related species, including ring-necked pheasants (Phasianus colchicus), red-legged partridges (Alectoris rufa), Kashmir native fowl (Kashmirfavorella), and Bangladesh native, Fayoumi, and Assil fowl (Gallus domesticus).
The number of secretive bitterns remains critically low but has reached 19 breeding males - one short of the year 2000 target - and stone curlews
exceeded their target of 200 breeding pairs.
The RSPB knows that changes to the CAP, especially the development of targeted agri-environment schemes, have also increased populations of certain scarce farmland birds like cirl buntings by a massive 130% from 1992 to 2003 and stone curlews
by 87% from 1997 to 2005," said Mr Kendall.