The UK countryside is being altered by the continuing use of dangerous amounts of nitrogen and phosphorus, according to a report.
The bittern was cited as being among the species at risk
The Royal Society for the Protection of Birds said "nutrient pollution" was impacting on wildlife.
The chemicals come from inorganic fertiliser, household detergents in sewage and fossil fuels, it said.
It acknowledged efforts to cut down on these but said more needed to be done by government, farmers and industry.
Levels of nitrogen and phosphorus have doubled and trebled respectively since the industrial revolution, the report said.
And fertiliser now accounts for about 60% of the nitrogen and about 80% of phosphorus used in the UK.
The number and variety of plants and animals was changing as a result and many species were under pressure, the report added.
"Strong causal links exist, in a number of cases, between nutrient pollution and knock-on effects on the food chain of wildlife, including birds," the report said.
"Damaging pollution of the countryside will continue unless action is taken to reduce the amount of inorganic nutrients reaching the environment from all sources.
"Knowledge and technologies exist to improve nutrient management in all sectors."
One bird, the red-backed shrike, was said to have been pushed to extinction in the UK by the intensification of agriculture.
And the RSPB said the bittern was among the species at risk.
A separate report from watchdog the Environment Agency has highlighted the threat pollution and growing demand is putting on groundwater supplies in England and Wales.
Nitrogen, pesticides, solvents and other chemicals were seeping through soils and from water running off roads and other surfaces, it said.
Pharmaceuticals such as the anti-bacterial agent triclosan, found in soaps and toothpastes, were also cited as a concern. It is thought bacteria that help break down other pollutants could be killed off.
"To many of us, groundwater is out of sight and out of mind," said Environment Protection Director Tricia Henton.
"But this hidden resource which provides clean, fresh water for our homes, industry, agriculture and the environment is a limited resource that must be properly managed and protected."
She said good progress had been made in recent years with bans on some pesticides and the doubling of the number of groundwater-monitoring sites.