One of the more important
features of reservoirs that may impose constraints on the local
wildlife is the variation in water levels that may occur. For
some breeding birds this has been overcome by the use of floating
platforms. Prior to the introduction of rafts no common terns
had successfully bred at Alton.
We now consistently manage to ring around 50 young each year.In
addition other bird species such as oyster catchers, coot and
geese have also taken advantages of these safe and consistent
breeding areas.Each raft is 10 feet square and is covered with
shingle and a few larger stones for protection. Additional shelter
is provided by timber shelves placed in the corners. A low fence
is put around the raft to reduce the ability of other, more
aggressive species such as geese, to push out the terns.
It is also
important to provide secure anchorage and, to this effect, we
have found that a single point attachment to a concrete weight
by means of a polypropylene rope and short length of chain is
more than adequate.Interestingly we have found that during the
early part of the season the terns venture to the local Stour
and Orwell estuaries to obtain the majority of the food with
flounders forming a large part of their diet. It is not until
late summer that the fry in the reservoir are big enough to
constitute a worthwhile meal!
