Breeding
Bird Survey 1999 - Introduction
Situated less than a kilometre south of Brancaster Staithe, Barrow
Common comprises some 33 hectares of acidic grassland and scrub with small areas of
secondary woodland. It is listed as a County Wildlife Site and although some
vegetation survey work has been carried out by the Norfolk Wildlife Trust, very little
published information exists on the value of the Common as a habitat for birds. To
help fill this gap in knowledge a breeding bird survey was carried out in 1999, the
results of which are presented in this report. The survey results define the
breeding bird community at this point in time and will provide a baseline against which to
measure future change. They may also be helpful in informing any future decisions
on the management of the Common.The winter
bird community has yet to be investigated in detail but some casual recording has been
undertaken by the author in recent years. This has mainly focused on roosting
passerines and the opportunity has been taken to present this information here as an
appendix to help give a more rounded view of the ornithological value of the site.
Methodology
The breeding bird survey used the territory mapping technique
developed by the British Trust for Ornithology (BTO) for its Common Bird Census (CBC).
This takes advantage of the territorial behaviour exhibited by most small passerine
birds during the breeding season and involves making ten complete visits to the site
during March-July and mapping each bird seen and/or heard during each visit on large scale
maps. This data is then transferred to individual species maps and a picture of
individual territories gradually builds up over the series of visits.
All territories overlapping the site boundary are included in the totals.
Results
The census results are summarised below followed by a more detailed
discussion of all species recorded. Pheasant and Woodpigeon were both present and
breeding on the site but were not censused.
Winter bird data and a list of butterfly species recorded are listed below.
Click on the name of the bird to see more detail
which is listed below
Birds breeding at Barrow Common in 1999 - Systematic List
Mallard
Several sightings of a single female flying from the Common towards the
coast. Nest not located but breeding considered likely.
Sparrowhawk
Single pairs nested in nearby woodland at The Downs and at Garners
Hill/Gas Plantation. Both pairs regularly hunted over the Common.
Kestrel
One pair nested in Garners Hill/Gas Plantation and regularly used the
Common for hunting.
Red-Legged Partridge
Two territorial pairs.
Stock Dove
Three territories. All located on the site boundary where mature
trees present.
Turtle Dove
Two territories, both centred on patches of dense mature hawthorn
scrub. This species has declined nationally by 77% since 1970 and every effort
should be made to maintain the small population on the Common.
Cuckoo
One male calling regularly from the northern part of the site
.
Barn Owl
Single birds were seen hunting on the Common on a number of occasions.
It is likely that these sightings relate to a pair breeding nearby.
Tawny Owl
One territory actually on the Common . Several other territories
in adjacent woodland.
Green Woodpecker
Two pairs nested in nearby woodland - one at Brancaster Hall and one
at Garners Hills Plantation. The pair at the latter site regularly used the Common
for feeding.
Greater Spotted Woodpecker
One pair bred in adjacent woodland at Garners Hills Plantation and
occasionally fed in trees on the Common.
Swallow
A bird seen showing interest in the old wartime building on the
northern boundary in April but appeared to desert the site before any attempt at breeding.
Breeding has occurred here in past years.
Wren
The most numerous breeding species with a total of 33 territories, a
density of 1 pair/ha. Showed a preference for low thick scrub. Especially
gorse. Open bracken areas and tall hawthorn scrub were largely avoided. Wren
populations tend to fluctuate with the severity of the winter and are likely to be
relatively high at present following recent mild winters.
Dunnock
Another common species to have benefited from recent mild winters.
A total of 21 territories located giving a density of 0.6 pairs/ha. This is
relatively high for natural and semi-natural habitats. Dunnocks have found their
ideal habitat in suburban and village gardens, parks, cemeteries etc. In these areas
densities may be as high as 5 pairs/ha. and under these circumstances Dunnocks have
developed extremely complex breeding systems where monogamous pairs may only make up
around 25% of the population, with other birds employing varying degrees of polynadry,
polygynandry and polygyny! It is as yet uncertain to what extent these complex
behaviour systems operate in more natural habitats where densities are typically lower but
it may be that CBC methodology is not ideally suited to unravelling the mysteries of
Dunnock breeding densities.
Robin
A total of 11 territories located giving a density of 0.3 pairs/ha.
This is roughly the same as that found in good mixed farming habitat with small
fields and good hedgerows but is lower than the 1 pair/ha. found in favoured woodland or
suburban garden habitat.
Blackbird
Only three territories located. The Common is not ideal
Blackbird habitat and the relatively low density is much as one would expect.
Song Thrush
The two territories located, both on the eastern boundary of the site,
were very welcome given that this species has declined nationally by 55% since 1970.
Mistle Thrush
A single territory in the Northeast corner of the site. There
were three additional territories in adjacent woodland.
Lesser Whitethroat
Two territories, both at the southern end of the site. This
species is characteristic of tall hedgerows and tall scrub edge.
Whitethroat
One of the typical species of the Common, very much associated with
low scrub but not where this is too dense. A total of 23 territories located giving
a density of 0.7 pairs/ha. Optimum habitat can support densities of 1 pair/ha. or
even higher but the Barrow Common figure is still impressive. Nationally, the
Whitethroat population is still recovering from a population crash in 1969-74 caused by
drought conditions in its wintering area.
Garden Warbler
Only one territory on the southern boundary. There would seem to
be suitable habitat for a few more pairs on the Common but this has always been a scarce
breeding species along the coastal strip in north-west Norfolk.
Blackcap
A total of 10 territories found. The Blackcap is really a
woodland warbler and densities of from 4-8 pairs/ha can occur in optimum habitat.
The Barrow Common density of 0.3 pairs/ha. is slightly higher than one might expect given
the limited area of suitable habitat and is probably a reflection of the very healthy
national population which has shown an increase of 155% since 1970.
Chiffchaff
This is another essentially woodland warbler that has increased
nationally in recent years. The population of 9 territorial pairs on Barrow Common
reflects the current high population levels.
Willow Warbler
The second most numerous breeding species on the Common. A total
of 29 territories located giving a density of 0.9 pairs/ha. This is in line with an
average of 1-2 pairs/ha. in good habitat.
Goldcrest
One or two birds recorded just within the southern boundary of the
site in early spring but no evidence to suggest that breeding was attempted.
Long-tailed Tit
Three territories located. About what one would expect.
Coal Tit
A single singing male recorded just within the southern boundary on
one date in early spring. This was probably just a wanderer from adjacent woodland.
Blue Tit
A total of 6 territories located. Strongly related to the
presence of mature trees.
Great Tit
4 territories.
Magpie
A single bird seen on the northern boundary on one date in early
spring but no further evidence to indicate breeding.
Chaffinch
A total of 7 territories located. The majority of these were in
the strip of secondary woodland along the northern boundary.
Greenfinch
One pair in the Northeast corner near Valley Farm.
Locally this is very much a species of village gardens with relatively few breeding in the
wider countryside.
Linnet
A characteristic bird of the Common showing a strong association with
Gorse as a nesting habitat. The total of 18 breeding pairs is a locally significant
concentration. Nationally, Linnet breeding numbers have declined by 38% since 1970,
on farmland the decline is even greater. At a local level this was well illustrated
in 2000 when a breeding bird survey of over 700 hectares of farmland found no breeding
Linnets. The maintenance of the Barrow Common population should be a major
consideration in any future management decisions.
Bullfinch
Only one pair found by the southern boundary, associated with the
large clump of Blackthorn. This is another farmland bird in serious trouble with a
national decline of 40% since 1970 which shows no sign of abating. Formerly more
frequent on the Common.
Yellowhammer
This is another species for which the Common is particularly
important, supporting a total of 15 territories. The density of 0.45 pairs/ha. is
equivalent to the highest densities found on farmland. The familiar story of
national population decline also applies here, in the case of the Yellowhammer by 43%
since 1970. A major difference however is that the Yellowhammer decline did not
start until the late 1980's and is still continuing at an alarming rate.
Summary
Barrow Common supports a breeding bird community that is typical of
acidic grassland and scrub habitat but is particularly important for its high densities of
Linnet and Yellowhammer.
The Linnet is on the Red List of Birds of Conservation Concern and in view of its
recent decline, the Yellowhammer is likely to be added to the Red List at the next
revision. The Common also supports small populations of three other Red List
species - Turtle Dove, Song Thrush and Bullfinch.
All the key breeding species are associated with scrub habitats - both
Gorse and Hawthorn - and it is important that any future management of the site makes
provision for this.
The following three species have bred on the Common in the past but were
not recorded this year despite specific searches. Long-eared Owl, Nightingale and
Grasshopper Warbler. Also, Woodcock could have been expected to breed in the
adjacent woodland and use the Common for feeding but none were recorded despite specific
dusk visits to check for 'roding' birds.
Winter Bird
Community
No structured work has yet been done to define the winter bird
community of Barrow Common. This could perhaps best be done by setting up a transect
route to be walked regularly in future winters.
However, some attention has been paid to winter roosting passerines. This
preliminary work has indicated that the Common is important as a roost site for some
species, particularly Linnet, and has served to further emphasise the importance of the
Hawthorn and Gorse scrub habitats which provide the favoured roost sites. Some
recent roost counts are given below:
Blackbird.......................................40
roosting on 7/11/99
Linnet........................................114 roosting on 21/10/98
".........................................140 roosting on 29/11/98
"..............................................91 roosting on 7/11/99
"...........................................60 roosting on 29/12/99
Yellowhammer.............................10 roosting on 21/10/98
".............................................18 roosting on 7/11/99
Other important species that use the site
regularly during the winter include Hen Harrier, Merlin, Woodcock, Barn Owl and Long-eared
Owl.
Butterfly
Species Recorded
During the course of the breeding bird survey work the following
butterfly species were recorded:
Holly Blue
Common Blue
Small Copper
Green Hairstreak
Small White
Green-veined White
Orange Tip
Red Admiral
Small Tortoishell
Peacock
Wall Brown
Small Heath
|
