Tony Quinn writes: The above graph illustrates the recent acceleration in the demise of bird species from the borough. In the preceding 50 years the only bird species I can think of, which may have left the borough are Nightjar, Hawfinch and Wryneck. I believe Nightjar certainly used to breed but I am not sure about the others and clearly the rate of extinction was low at about 1 species in 16 years. We now have reached a frightening rate of one species every 3 years. If that is happening to birds just think what is happening to insects!!
Yellow Wagtail, Reed Warbler and Redshank
were the first species to disappear when Epsom Sewage Farm closed
in 1957. This single event removed the one large marsh area in
the borough and, as it was not really a natural event, I have not
included these in the calculations. The proximity of its closure
to the start of the period would distort the graph.
There is a chance that with some habitat enhancement Reed Warbler may return. Indeed it has bred in at least one recent year in Horton Country Park. There is no hope for the other two though.
The demise of Red-backed Shrike in 1960,
shortly after the start of the term, brings another unnatural
peak which the solid curve only, ignores. Scrub clearance along
the Hogsmill valley did not help this species, but it last bred
on Epsom Common, when the start of a national decline became
evident. Only one or two pairs now breed in the UK. Climatic
change was thought to be the reason so perhaps the first signs of
global warming.
Lapwing
was probably the next to go but the date is a guesstimate. It
used to breed on Epsom Sewage Farm but 1970 makes the assumption
that it continued to breed, unrecorded, somewhere on the
psychiatric hospital farms. Indeed it still breeds on
neighbouring Park and Rushett Farms in Kingston. There is little
hope of it re-colonising the borough though as possible habitat
is now too disturbed.
The
unchecked progression of Epsom Common to woodland eliminated the Stonechat
from the borough in 1980. This is a species that could return as
much work is now being done to revive the open aspect of the
common. Some good stands of gorse and heather would be a help and
since the species is seen in the borough most winters, there
could be a chance they would stay and breed.
Redpoll
probably only bred in low numbers during the first 15 years or so
but during the 70’s there was a population explosion and it
became quite common, even breeding in gardens. It then went into
rapid decline and last bred in 1983. It still breeds in low
numbers in Surrey, mainly on higher ground, perhaps a consequence
of global warming. There is little hope of re-colonisation in the
near future.
The Surrey Bird Report records Grey Partridge breeding
in Epsom as recently as 1989 but is not very specific about the
exact site. I have a suspicion that this may refer to Rushett or
Park Farms, which are actually in Kingston but adjoin Epsom
Common and Horton Country Park. There has been a huge national
decline of this species due to changes in farming practices and
there is little hope of it breeding in the borough again.
Another multiple event occurred around 1991 with the
last breeding of Tree Sparrow, Turtle Dove and Willow
Tit for the following reasons. Tree Sparrow’s
national decline can again be related, with some certainty, to
changes in farming practice and it is now something of a national
rarity having become extinct in many counties. A large colony is
artificially maintained on Beddington Sewage Farm near Croydon,
where nest boxes and a feeding program compensate for the habitat
changes instituted by Thames Water as they develop the site. The
year of demise from Epsom is not certain but some winter records
that year give a clue that they were around locally, perhaps at
Warren Farm.
Reading county bird reports at the beginning of the
period, one might be forgiven for thinking that Turtle Dove
simply did not exist but the truth is they were so common that
editors could not find anything interesting enough to write about
them. Among the references I have found are autumn flocks of 90
and 100 on Epsom Sewage Farm, now the Longmead Estate. The
species is disappearing rapidly and is now only common in some
eastern counties. Shooting during its migration along the French
coast is a contributory factor but changes in farming methods and
climatic change have no doubt also played their part. If this
continues it is likely to become extinct in Britain in the
foreseeable future.
The Willow Tit’s disappearance
is again related to a national and as yet unexplained decline. It
has bred on Epsom Common and around Nonsuch Park.
Again, the progression from
scrub to woodland on Epsom Common eliminated Nightingale
from the borough. Although it has greatly declined nationally,
the species still breeds fairly close at Bookham Common and
perhaps also Ashtead. It is hoped that similar suitable habitat
can be recreated on the common again to attract them back.
A
third multiple event saw the disappearance of Rook, Marsh Tit and
Grasshopper Warbler in 1997. Epsom Downs held the only recent
small Rookery in the borough and there is a good chance
that they could continue to breed from time to time. Indeed it is
possible that a Rookery still exists on private land somewhere in
the borough. Marsh Tit disappeared for the same reasons as
the closely related Willow Tit and is again associated with Epsom
Common.
There is no obvious sign that the rate of loss is
going to decrease as a number of other species are very much on
the edge in the borough. There is probably only one pair each of
Great Crested Grebe, Woodcock and Reed Bunting, whilst Kestrel,
Tawny Owl, Grey Wagtail, Lesser Spotted Woodpecker, Spotted
Flycatcher and Yellowhammer are all very scarce.
In the context of these losses Epsom Common has often been a last breeding site in the borough with Red-backed Shrike, Stonechat, Lesser Redpoll, Turtle Dove, Willow Tit, Nightingale, Marsh Tit and perhaps Grey Partridge all disappearing from there.
In the graph above I have attempted to separately indicate the true colonists (lower line) from total arrivals (upper line) and this gives a more accurate indication of what is happening naturally rather than unnaturally. If this is done, a natural colonisation rate of one species every 12 years as against one every 6 years for all comers is arrived at.
The difference between true colonists and total arrivals is accounted for by ‘introduced’ and ‘feral’ species. These mean escaped from captivity and now breeding in the wild of, either exotic, or indigenous species. Clearly this is not often welcome and can present us and our countryside with unwanted problems. Examples of this are Ruddy Duck, Mink, Coypu and New Zealand Stonecrop and Japanese Knotweed in the plant world.
Our first bird colonist was Collared Dove and
thankfully its arrival was both natural and very remarkable. From
about 1930 its range expanded dramatically in a NW direction from
the Balkans area, arriving in Britain in the 50’s. There
appear to have been few problems and it has filled a vacant
ecological niche.
Not quite the same with Canada Goose, the
next arrival. Although it breeds at similar latitude in N
America, its breeding habitat is in very much wilder terrain.
Here, since the early 60’s its numbers have gone rather out
of control and it has become a bit of a pest. Being such a large
bird it can have a detrimental effect on some of our native
ground-breeding species.
Of these
introduced species, my opinion is that, only the Mandarin is
welcome, because its colonisation seems not to have had negative
effects. It is endangered in its native China, so the British
population provides another gene base and, unlike the previous
species, its numbers do not seem to have escalated out of control.
Beautiful though it is the Ring-necked Parakeet
introduction is, I believe, likely to become a problem in future.
I have not heard much detrimental comment as yet but it is a
powerful hole nesting species and as such, if it spreads much
futher, is likely to oust some native species.
The Great Crested Grebe is a welcome colonist
and only breeds on the relatively recently re-constructed Epsom
Common Great Pond. Little Grebe has also bred erratically here
and in Horton Country Park but is not included in the study as it
has done so only rarely.
Tufted Duck is included as a colonist but
although it is a native breeding species, it did not used to
breed in town parks and the like. It is possible that our
population derives from escapes from collections.
The Grey-lag Goose breeds genuinely in the
wild, only in the Hebrides in the UK. A feral population has long
existed at Hornsey Island in Essex and these have spread
dramatically in recent years. No doubt escapes from collections
are involved as well. Recently, there have been records of
breeding in the Bourne Hall region. They may hybridise with
Canada Goose too.
The latest
colonist is the Grey Heron, which has recently started to
breed regularly in Horton Country Park. There are also some past
isolated records of attempted breeding on Epsom Common.