SOME of the first ever images of an otter inside a holt have been recorded at a holt constructed at a Fenland location.
Cliff Carson, Environmental Officer for the Middle Level Commissioners, (MLC), built the holt - an otters underground den - for The Co-operative Farms at their Coldham Estate in mid July.
MLC manage 120 miles of Fenland rivers and drains for flood defence and navigation, in a 70,000-hectare catchment, and are active in promoting biodiversity projects.
The images of the otter were recorded less than four months after the holt was built. An infrared camera that was installed during construction, to view activity inside the holt, recorded an otter visiting and inspecting the underground den.
The series of motion-detected video clips showed an otter visiting the holt five times over a three week period during November and December. On each occasion it left a spraint, a scent marker left to communicate its presence to other otters, on the bedding inside the holt.
Images taken inside an otter holt are very rare, and it is believed these are among the first to be recorded.
This holt construction and the monitoring equipment was funded entirely by The Co-operative Farms. Farm Manager Russell Armstrong contacted Cliff Carson about installing a holt at the farm because of his experience in creating them as part of the Middle Level Otter Recovery Project.
Since 2007 nearly 40 holts have been created at other sites on MLC waterways and Internal Drainage Board ditches as part of the project. The aim is to provide a network of resting places for otters throughout the catchment of the Middle Level system.
Otters numbers declined by over 90 per cent during the 1960s and 1970s, due to persistent chemicals entering the food chain from sheep dips and seed dressings. Withdrawal of the pollutants has seen a slow return of otters to nearly every county in England. The provision of a network of safe sites in the Middle Level waterways, will allow otters to return to their former numbers.
Other river management actions by MLC, to benefit biodiversity generally, have helped improve habitats for otters. Leaving a meter wide strip of emergent vegetation uncut for at least two years at the edge of their rivers has resulted in good cover for otters as they move about the system.
Cliff Carson said: "It was a tremendous moment to see the first images of an otter using one of the holts we have provided.
"Everyone who has helped with the project here, especially the MLC workers who worked hard moving breeze blocks and paving slabs to build them, has had a real boost to their Christmas spirits.
"The images are very up-close and personal, giving good views of sprainting activity. We look forward to getting further insights into how otters behave inside their holts which have, until now, been a very private part of their lives."