A survey of UK farmers has revealed that 96% think environmental work on their farms would be impacted if payments for wildlife-friendly farming were stopped or reduced.
The RSPB conducted the survey to determine the effect on so-called agri-environment schemes, amid fears that budget cuts are imminent.
Results showed that 51% of farmers asked said they believe the environmental work would be impacted "severely", and 7% think it would "stop" altogether.
Only 4% said environmental work on their farms would be unaffected.
The wildlife charity claims that "signals" coming from politicians in Europe and the UK point to an uncertain future for the 25-year-old EUfunding.
It said a reduction could spell disaster for wildlife in England and abroad.
Widespread but declining species such as the skylark and yellowhammer rely on the work, as do less well-known species, including cirl bunting and stone-curlew.
RSPB South West spokesman Tony Whitehead said species could be lost from our countryside "within a decade".
The poll also revealed how the payments maintain the financial viability of some farm businesses.
Some 71% said the schemes were important; 8% claimed they are "completely vital".