The summer that was every bit as bad for wildlife as the coldest winter

Some of Britain's most endangered creatures were dealt devastating blows by the monsoon summer which ended yesterday.

The effect on wildlife of the weeks of incessant rain and the unprecedented floods which followed was so acute that some species are likely to have suffered local extinctions – and isolated populations may never be able to be re-established.

From water voles to swallowtails, from partridges to bumblebees, species which are rare, declining or even just grimly hanging on suffered catastrophic losses, especially of their young, right across the country.

When the full picture is eventually assessed, Britain's wettest summer on record may be found to have had an effect as damaging as the 20th century's worst winter, 1963 – when millions of wild creatures died in a landscape that was snowbound for two-and-a-half months, and some species, such as the Dartford warbler, were brought to the brink of extinction in the country as a whole.

It is far too soon for a full statistical picture of summer 2007 to emerge, and the evidence of what has happened to wildlife is largely anecdotal – but the anecdotes are all pointing in the same direction.

Take birds, and one of Britain's rarest species, the bittern – the brown, long-legged relative of the grey heron which nests in the reedbeds of East Anglia.

Bitterns are counted by the number of males that are "booming" – making the low, far-carrying call that attracts the female. Within the past 20 years there were as few as 11 booming males in all of the country, but strenuous conservation efforts had this spring brought that up to more than 50.

Then disaster struck. After 2007's wonderfully warm April, cold and rain swept in during the early May Bank Holiday weekend. At Minsmere, the flagship reserve of the Royal Society for the Protection of Birds in Suffolk, five bittern nests were washed away, and the young birds died in the low temperatures. "It was cold and wet right across the bittern's breeding range," said Mark Avery, the RSPB's director of conservation. "One wet cold weekend dealt a devastating blow to one of Britain's rarest birds."

But it wasn't just bitterns. Two of Britain's most rapidly-declining farmland birds, the lapwing and the grey partridge, have also suffered terribly from the washout summer. Paradoxically, the lapwings were hard hit by the hot April, because the dried ground was too hard for them to dig out the invertebrates to feed their chicks. But then they were dealt a double whammy by the downpours which followed, and when rivers such as the Severn burst their banks in areas such as Gloucestershire, many nests in the riverside meadows were washed away and the chicks drowned.

The effect of the cold and wet on the grey partridge, which from being a common and familiar bird has declined by nearly 90 per cent in Britain as a whole and is now extinct in many parts of the countryside, was so lamentable that the Game Conservancy Trust issued a special warning notice about what had happened. "Urgent conservation action needs to be taken by all those with a responsibility for managing the British countryside," it said.

As with birds, so with mammals, and what may seem at first sight to be a curious victim of a wet summer – the water vole. Ratty of The Wind in the Willows was once common but now, because of the depredations of wild American mink, is our most endangered wild animal. The swollen river levels are thought to have drowned many water voles in their burrows.

But the toll taken may be locally very high, according to Brian Eversham, of the Bedfordshire Wildlife Trust. "It's because many of the water vole populations are now small and isolated," Mr Eversham said. "If they are wiped out in an area, there may well be no other nearby population to recolonise it." Perhaps the worst-affected wildlife sector of all this summer has been invertebrates, comprising insects, spiders, worms and other creepy-crawlies. The warmth of April gave butterflies in particular a fantastic start – 11 British species recorded their earliest-ever emergence dates – but the deluges and cold that followed did real damage.

Britain's most spectacular species, the rare swallowtail, appears to have had a very poor breeding year in its only home, the Norfolk Broads, where flooding has reduced the availability of the insect's food plant, milk parsley, and also appears to have drowned many caterpillars. But other uncommon species have also suffered badly, such as the Duke of Burgundy, where in some areas it was raining for its entire month-long flight period – meaning mating is much less likely to take place.