Aphids were found to be very responsive to climate change

The study by Scottish Natural Heritage (SNH) recorded 500 spring and summer events such as bird migration, egg laying and plant flowering.

It said 74% of the events showed some evidence of being earlier, a third of which were "significantly earlier".

The study monitored events in the second half of the 20th Century.

The report, Natural Heritage Trends of Scotland, shows some species are more adversely affected than others, raising the prospect of disrupting food chains.

This is the most comprehensive report yet on the timing of biological events related to climate change in Scotland Prof Colin Galbraith SNH

The researchers said butterflies arrived 7.6 days earlier over a 28-year period, while moths advanced an average 5.1 days earlier over a 31-year period.

Birds are nesting four days earlier than 38 years ago and records of the first eggs laid by dippers in Scotland have advanced by about nine days.

Aphids appear to be particularly responsive to climate change, as scientists are now first catching them on average 16 days earlier than at the start of a 34-year period studied.

The seasonal cycles of many types of marine plankton, the food for many other species in the sea, are also becoming earlier, with one particular species advancing its seasonal peak almost four weeks since the 1950s.

Thorned aphids were among the creatures studied

Tim Sparks, one of the authors of the report, who is based at the Centre for Ecology and Hydrology, said: "This could have a knock-on effect on species higher up the food chain, such as commercially important fish species."

SNH, a government-funded conservation body, said the changes were linked to temperature rises in the environment and were evidence of climate change.

Professor Colin Galbraith, of SNH, said: "This is the most comprehensive report yet on the timing of biological events related to climate change in Scotland.

"If we needed any more proof that climate change is a reality then it is contained within these pages.

'Food webs'

"These results show that species are responding at different rates to the effects of warming temperatures on land, air, freshwater and sea, and this could ultimately mean that timings of natural events will become so out of balance as to affect food webs and competition between species."

Prof Galbraith said there was an urgent need to develop conservation plans to help protect vulnerable species in Scotland and to reduce carbon emissions.

The authors analysed data on air, water and sea temperatures from the UK Meteorological Office and the Royal Botanic Gardens Edinburgh, the Scottish Environment Protection Agency and the Scottish Executive.