“I promise you, they are not remote controlled,” said our ecstatic tutor, Darren Tansley, as we spent a couple of hours with water voles – one of Britain’s rarest creatures – scampering along the river banks and dipping in and out of the river.

When we pulled up in our minibus, Ratty seemed to be waiting for us and wasn’t in a hurry to dash off as the sun shone in the Essex countryside.

I was on a Field Studies Council course entitled Otters, Water Voles and Other Riverside Mammals, based at Flatford Mill, and today was meant to be mainly about spotting signs of otters.

However, here we were tucking into our packed lunches with water voles almost continually putting on a show. Occasionally, they would embark on a longer swim living up to Darren’s description of them as “hairbrushes with an outboard motor”.

The previous day was focused on water voles, and though we had a couple of brief sightings and had seen many latrines, feeding stations and burrows – they remained largely elusive.

I didn’t really expect to see any because they are so few of them now in the UK. But then again, we were near on the River Colne where 600 water voles had been moved to earlier this decade to escape port development work on the Thames.

As the country’s fastest declining mammal, according to The Wildlife Trusts, water voles need our help. They are already extinct in Cornwall.

Threats include habitat loss due to riverbank management, drainage of ditches to prevent flooding and heavy grazing from cows, sheep and deer. And as each vole has to eat half its body weight in vegetation a day, they are simply running out of food.

Mink also pose a menace. Native to North America, these mustelids were brought over in the 1920’s for the fur trade and escaped into the wild a decade later. Many more were released by wildlife activists in the 1980’s.

These aggressive predators have water voles on their menu and can squeeze into their burrows to devour even whole colonies.

Thankfully there are volunteers willing to give up their time to learn more about water voles in the hope of helping to protect them.

Many will be taking part in the Water Vole National Monitoring Programme this month, which aims to find out if and how many water voles are at certain sites around the country.

Will any luck the conservationists’ efforts will be rewarded with such joyful sightings as we had.

For more pics see my flickr gallery