The coldest winter in more than 30 years has devastated wildlife, say experts.
Thousands of water birds such as herons and kingfishers are likely to have starved to death, unable to break through ice on ponds and streams to get food.
Tiny birds such as the wren and goldcrest will have frozen in the prolonged sub-zero temperatures.
Small mammals such as the shrew and overwintering butterflies including the red admiral will also have been badly hit.
But the bitter weather will have been welcomed by some species. Hibernating mammals need the cold to stay asleep, and freezing temperatures help kill off parasites and diseases.
Today, however, is the first official day of spring and it marks an end to the coldest winter since 1979.
British Waterways, which looks after 2,200 miles of canals, said the cold winter had hit birds which feed from still or slow-moving water.
Mark Robinson, who is asking the public to take part in the British Waterways annual wildlife survey, said much of nature was 'pretty resilient' to cold winters. But he warned that kingfishers and herons are likely to have suffered badly.
'It is therefore particularly important for us to monitor what species need our support.'
Grahame Madge, of the Royal Society for the Protection of Birds, said: 'It's worth remembering this was a return to the sort of winters that were common 30 years ago.
'All the species affected have lived though this kind of typical British winter for hundreds or thousands of years.'
Sightings can be recorded at www.waterscape.com/ wildlifesurvey.