Some 95 bird species, including the barn owl, are in serious decline in Ireland and many, such as the corn bunting, have already become extinct, the Heritage Council has warned.
The council, which is preparing to celebrate World Biodiversity Day tomorrow, said that in addition to the birds at least 120 plant species were endangered and a "major national effort" was urgently required to halt the decline.
The decline in biodiversity - the natural range of animal and plant life required for a healthy environment - is a result of pressure on the environment from a wide range of factors including farming, industry and even household chemicals.
While there are tens of thousands of barn owls in the country, unsympathetic restoration of old buildings is depriving them of nesting places, while a decline has been noted in the rural rat population, with rat poison affecting their food.
The barn owl population has declined by about 25 per cent in the last two decades and this pace is accelerating, according to the council.
In 2002 the Government published the National Biodiversity Plan to sustain plant and animal life but the Heritage Council said not enough money was available to carry out the measures outlined in the plan.
The council said many more plant species would now be already extinct but for cultivation and breeding programmes in the National Botanic Gardens.
"A serious national effort is urgently required and the Government, local authorities, industry, farmers and the general public will all need to make rapid changes to halt the decline," it said.
Pollution, the use of pesticides, chemicals, and intensive farming can all lead to loss of natural habitats such as hedgerows, grasslands and wetlands and so lead to loss of biodiversity, it pointed out.
A prime example of the decline is the pearl mussel, which is protected under the EU Habitats Directive but which is under serious threat.
A study carried out in 2004 in the southeast shows that it is now facing extinction due to water contamination and loss of habitat.
"Reductions in biodiversity in Ireland have serious health and socio-economic implications," said Dr Liam Lysaght, ecologist with the Heritage Council.
"Everything in nature is linked into an intricate web and when a species goes into decline, it has a knock-on effect on other species and also on people."
The number of salmon caught in Irish waters has been declining rapidly since 1975.
Yet, if managed effectively, the salmon angling resource in the country could be worth €100 million to the economy, and much of this to the less economically vibrant parts of the country, Dr Lysaght said.
"The contribution a healthy and diverse countryside makes to the quality of life and tourism resources in incalculable."
Dr Lysaght said additional money was needed for:
