Are otters living near Verulamium Park in St Albans?

The broken shells of swan mussels by the side of Verulamium lake (Image: Archant)

That is the question poised by a Herts Advertiser reader who has noticed the large number of broken and empty mussel shells - known as swan mussels - on the periphery of the lake.

Richard Coleman, of Sunderland Avenue, St Albans, has been walking by the lake for the best part of 30 years and has only noticed the shells recently.

On one recent excursion he spotted clear animal tracks around the shells - and by comparing them with various reference pictures believes they could indicate that an otter is the culprit.

Richard said he was aware that freshwater mussels were eaten by some birds and also animals such as mink and rats but was puzzled about why the shells had only recently appeared.

He went on: “I am aware that otters have extensive home ranges and can travel many kilometres whilst foraging so my hypothetical animal may not actually be resident in the Verulamium area.

“However, the fact that they are increasingly being seen in urban locations would provide a plausible explanation as to why the predated mussels have only recently started to appear.”

Richard urged any readers who might have seen an actual animal rather than a paw print to report it.

A spokesperson for St Albans district council which maintains the lake said it was common when swan mussels reached the end of their life for them to come to the surface where they would be eaten by a range of birds and animals including herons, geese and rats.

He said that parks staff had not received any reports of otters in the lake and would have expected the end of the shells to have been chewed if that was the case.

But although the lake was recognised as a breeding ground for the mussels, more shells than normal had been noted in recent months by parks staff and members of the public, he added.