CROW (Conserve Reading on Wednesdays)
Wednesday, 7th September 2016
Hosehill Lake, Theale ~ Sand Martin Bank maintenance
Hosehill's Sand Martin bank was built about 20 years ago by volunteers who have since been responsible for its maintenance.
It was constructed to provide an artificial nesting site for Sand Martins and it is estimated that between 45 and 60 pairs nested there this summer. The bank consists of a breeze block wall into which holes have been drilled, behind the wall is a further wall and the space between the two is filled with a soft sandy soil. The birds enter the wall via the holes and then excavate tunnels in which they make their nests. At the end of each breeding season volunteers remove the old nests using long handled "bottle" brushes, then the sand immediately behind the front wall is removed and sieved to take out any detritus before being returned to the bank so that the birds must create new tunnels on their return the following year (their preference).
When originally constructed a row of wooden pallets covered with plastic sheeting had been placed against the rear wall apparently to reduce the quantity of material needed to fill the space. These were now badly decayed causing holes to appear in the filling and it had been decided to excavate along the rear wall so the old timber could be removed and new pallets installed. CROW had been given the opportunity of starting this work.
The bank had been constructed so that it and at the appropriate time of year, its inhabitants can be viewed from the path which goes around the lake.
The top of the bank is protected with corrugated sheets to keep the sand dry. The first task was to remove these.
Part of a mound of earth behind the bank, probably created at the time of its construction, was levelled to provide a larger working space.
Each year a certain amount of the filling is lost in part a result of the bird's excavation. Elsewhere on site a reserve of the material is kept some of which was barrowed to the bank where .....
..... it was spread out to dry and any obvious stones removed.
All material to be used to fill the bank whether removed from the bank or new material to replace that lost is allowed to dry and then sieved to remove stones and other unwanted matter. It is placed in the bank in two inch layers and sufficient water added to each layer so the material holds together but is not over wet, .....
With the covering removed the holes resulting from the decaying pallets are visible.
Sheeting is laid down on to which the excavated material can be placed.
Mid morning and it's time for a break!
While work on the bank was progressing others were cutting back the vegetation to either side of the bank .....
..... as well as removing some of the reedmace growing at the foot of the bank.
"Where would you like this?"
Growing in the damp soil near the base of the bank was a patch of Orange Balsam; a non-native species related to the Himalayan Balsam, it is far less vigorous than its relative and therefore not considered a threat.
As work progressed the blackened timber of the old palettes became visible.
Occasionally the remains of an old nest including fleas would be uncovered.
Getting into the narrow trench while it had its advantages was no easy matter.
The large Shuvholer (a tool intended for use in the digging of post holes) proved to heavy and cumbersome for removing material from the narrow trench especially given the fine, dry nature of the material being removed.
Afternoon and the trench was now around 4 feet in depth (1200mm) and only a few inches (100mm) of material remained to be cleared but the exertions of the day were starting to take their toll and it was decided it was time to stop and leave the regular volunteers who meet at the site every Saturday morning to complete the task.
The Theale Area Bird Conservation Group who created the bank have a task at the Hosehill every Saturday morning, for more information visit www.freewebs.com/tabcg.
Created: Thursday, 8th September 2016
Photographs: Alan Stevens, Dave Barks, John Lerpiniere