Mammal Survey in Aldersbrook Exchange Lands
On Friday 29th August 2014, Darren Tansley, Water for Wildlife Officer for the Essex Wildlife Trust, and Tim Harris, from the Wren Wildlife and Conservation Group, set out 30 small mammal traps in the Aldersbrook Exchange Lands. This is the site of the old Redbridge Southern Sewage Works and now is mostly part of Epping Forest, with a central area belonging to Thames Water Authority. (for more information on the site, click here)
The traps used were Longworth Traps, which are designed to trap small mammals live so that they may be examined. Even when the trap is sprung there is a small hole for very small mammals to escape; Shrews need to eat continually, or they will die.
This operation was on behalf of our local Wren Wildlife and Conservation Group, and the following morning Darren gave ten Wren Group members some fascinating insights into the behaviour of voles, mice and shrews. The catch was four Wood Mice (2 males, 1 female and 1 that escaped before being sexed!) and a single Field Vole. There was also plenty of evidence of shrew activity, with both Common Shrew and Pygmy Shrew likely to be on site.
Darren raised a number of possibilities regarding the Exchange Lands. He thought there was a reasonable chance of Harvest Mice being present on the site. Apparently this species can colonise in only a few years of changed habitat status, and the site has been changing since it was closed as a sewage works in 1978 and later redeveloped to become part of Epping Forest in the 1990s. He also thought the Roding margins were worth checking for Water Shrews. And then, of course, there are Water Voles and Otters to look out for. Water Voles used to be a common inhabitant of the Roding adjacent to this site as well as through Wanstead Park. They became scarce by the early 1990s, although one was seen in 1998 and again in mid July, 2004. Since then, I have not heard of any being present. This may well be due to the presence of American Mink. Otters, however, are now not far upstream, and there have been one or two unconfirmed reports of sighting in the Roding by Wanstead Park, so surely it is only a matter of time?
Information supplied by Tim Harris - Photos by Rose Stephens
Paul Ferris, 1st September 2014