Otters filmed visiting a new holt in Cambridgeshire
A field mouse and otter make the Cambridgeshire holt their new home
Otters have moved into a recently-constructed holt on a farm in Coldham.
The Cambridgeshire farm's holt was installed in July 2010 and otters were first filmed using it during November.
Cliff Carson is an environmental officer with the Middle Level Commissioners, the body responsible for the upkeep of Fenland rivers.
This is the 39th holt he has installed but the first time he has seen an otter using one. He described it as "very, very exciting".
Mr Carson explained that the otter footage from Coldham was particularly interesting as it often takes years - rather than months - for the mammals to get used to man-made holts and begin to frequent them.
Otters began using the holt a few months after installation
Since joining the Middle Level Commissioners in 2005, he has been working on a number of conservation projects in the Fens, including constructing and installing otter holts in suitable locations.
One of the most reliable signs of otter presence are spraints (otter droppings) which are usually seen within a metre of a watercourse.
When Cliff Carson spotted spraints at the Coldham Estate, he installed the holt complete with an infrared motion-detector camera system.
Both the otter holt and camera were funded by The Co-operative retail group, which owns the farm.
Staff on the estate are keen to use environmentally-friendly farming methods, and as well as the holt, they have bee hives and wind turbines.
Assistant farm manager, Tom Paybody, said: "It's a real boost for the guys on the farm. On a cold winter's day it cheered everybody up when we showed them the otter footage."
Cliff Carson and assistant farm manager, Tom Paybody, at the otter holt
Mr Carson continued: "Some people are sceptical about the benefits of installing holts like this, but with this type of camera we should be able to find out much more about how otters use these constructed habitats where natural sites are missing.
"We have cameras in our other holts, but this is the only one that is connected to a permanent power source.
"So far, the otters have visited five times over a three-week period and only stay in there for about a minute.
"We think there may be two of them, so of course what we're really hoping for is that we might get some babies."
Until that happens, Mr Carson and the farm workers can watch footage of the holt's other visitors - rats, mice, mink, spiders and moths.
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