The Essex Naturalist
97
Barriers to Movement
The M25 has high fences and extremely large flows of fast moving traffic
bisecting the forest east to west. The motorway prevents dispersal between the
forest and the bufferlands to the north except in four potential crossing places -
Woodredon Bridge, Crown Hill road underpass, Copped Hall Bridge and the
Selvage "deer" Tunnel. Two other potential crossing places were identified but
rejected on inspection; to the east of the forest where the motorway passes
through a tunnel at Epping Thicks, and to the west where a road passes under
the motorway between Sudbury Farm and Wood Green. However the tunnel
site was blocked on the northern side (in terms of deer movements) by houses
and a nursery. The Sudbury Farm point was a road with no pavements and
inadequate cover for the deer to disperse to once they had crossed. There were
several dogs in kennels in the north of the crossing as well.
Each of the suitable crossing points was closely monitored on 11 occasions.
The cover near the crossing points was scrutinised for browse damage, the
ground surveyed for slots, and most of all, the surface and approach to each of
the sites was closely studied for slots. Any signs within 20 m of a crossing site
were noted.
Table 6: Survey of deer crossing the M25
The only crossing point with a surface which readily showed impressions
along its length was Woodredon Bridge. This bridge also had the advantage of
frequently forming a puddle across the whole width of the bridge which lasted
for a few days after rain fell, making the discovery of slots in the soft mud at its
edge rather easier. Copped Hall Bridge has a concrete surface and so does not
take impressions, but there is a strip of earth/mud just before it on which any
animal crossing the bridge must leave an impression after a wet day. The Selvage
deer tunnel is loose, shifting gravel inside which does not take tracks, but again,
there is a convenient strip of mud-prone earth at the northern end of it, where
tracks and footprints can be clearly seen. The Crown Hill road underpass is the
most difficult to be sure of. There are several large areas of sand under it which
readily accept tracks, but none which spans the entire underpass. Then there are
the narrow (often muddy) paths leading up to it which certainly show tracks,
but, again, they do not span the whole width of the bridge. It seems unlikely
that a fallow would choose a tarmac road surface rather than a more natural