Could it be that one of the birds we warm to most readily is forewarning us of trouble?

The numbers of puffins on the Isle of May, five miles off the Firth of Forth on the east coast of Scotland, has dropped by 30 per cent since 2003.

Some birds have arrived underweight, others have flown in later than usual. Others still have not turned up at all and are either not breeding this year or are presumed dead. Scientists think that too little food, or at least too little nutritious food, is to blame for the birds' failure to appear at the UK’s largest puffin breeding colony.

Puffins are amongst our most resilient seabirds because of their varied winter diet and because they dive deep for their food rather than fishing on or just below the surface of the sea like kittiwakes and Arctic terns.

Many seabirds including puffins rely on sandeels in summer, however, and sandeel numbers have plunged recently, particularly in the North Sea where sandeel fishing quotas have been substantially cut as a result.

Birds can sense when they are not fit to breed and it may well be that the shortage of sandeels in summer and changes in their more varied winter diet are leaving puffins and other seabirds unable to reproduce. A symptom of the food shortage may be the increasing numbers of nutritionally-poor pipefish being fed to puffin chicks in summer.

It is not clear why pipefish numbers have risen so steeply as sandeels have declined but we do know that the North Sea’s plankton is changing from cold-water to warm-water species as seawater heats up.

Sandeel larvae thrive on cold-water plankton and in its absence the number of sandeels will drop. Effects further up the food chain are inevitable, for larger fish like cod and for seabirds.

Evidence that seabird declines are linked to climate change is growing though we cannot yet be certain. What is sure is that global warming is adversely affecting our seas and other sealife.

We must act more quickly to slow the effects of climate change if we are to keep our best-loved wildlife and much else besides. We must also ensure that sandeel fishing quotas, which vary each year, are not increased to such an extent that they aggravate the impact of the subtle changes taking place in our seas.

Read more on the Isle of May puffins here