Breeding waders and other waterfowl on Suffolk estuaries in 1988, TJ Holzer, CH Beardall, RC Dryden

Tags: Suffolk, Ringed Plover, study area, grassland, wildfowl, Redshank, total area, total population, pairs, ha, population, recorded, British population, peak density, saltmarsh, waders, Oystercatcher, Suffolk coast, Blyth estuary, the Blyth
Content: 3 BREEDING WADERS AND OTHER WATERFOWL ON SUFFOLK ESTUARIES IN 1988 T. J. Holzer, C. H. Beardall & R. C. Dryden
This paper summarisesthe results of a survey of breeding waders, wildfowl, gulls and terns on grasslands, shingle and saltmarshes adjoining estuaries in Suffolk in 1988. A total of 3727 ha were surveyed and 1174 pairs of wildfowl, 1454 pairs of waders and 11,675 pairs of gulls and terns were found. The Suffolk coast is an important breeding area for waders. It supports 35· of British breeding Avocets, and over 1· each of Ringed Plovers, Redshanks and Oystercatchers.
INTRODUCTION
The drainage
of lowland
Grassland
and
the
claiming
of saltmarsh
for
agriculture
and
industry
are an all too familiar
story
in
Britain.
These changes in Land Use have been
accompanied by a decline in their ornithological
interest,
particularly
as a breeding habitat
for
wildfowl
and
waders.
In 1982 the British Trust for Ornithology
(BTO)
surveyed the distribution
of waders breeding on
lowland
Grassland
in England and Wales
(Smith
1983).
This study revealed very low densities
of breeding waders on most sites,
with large
areas
of grassland
holding no waders
at all.
Moreover
a significant
proportion
of
the
breeding
waders were concentrated
on relatively
few sites.
Populations
of Snipe,
Redshank,
Lapwing, and Oystercatcher
were predominately
in
the south east of England,
with the latter
three
species
concentrated
on the
coastal
marshes
of East Anglia and North
Kent.
The
survey also highlighted
the contracting
range of
Kedshank
since
the 1930s.
The BTO survey (Smith 1983) was primarily
aimed
at lowland grasslands
and although
no attempt
was made to include
areas of saltmarsh
it
was
acknowledged
that
such areas may be of Great
importance
for
breeding
waders.
The
significance
of saltmarsh
as a breeding habitat,
particularly
for
Redshank,
has since
been
established
(Green et al. 1984).
This study
also demonstrated
that the methodology
employed
in previous
surveys
may have
significantly
underestimated
breeding populations
of Redshank.
In 1985
Allport,
O'Brien
& Cadbury
(1986)
assessed the breeding populations
of redshank on
77 plots
of saltmarsh
throughout
mainland
Britain
and the island
of Mull.
Particularly
high densities
were reported to breed on the
Deben estuary,
Suffolk.
These studies
on selected
sites
of saltmarsh
and
grassland
in Suffolk's
coastal
region
have
indicated
that
this area may be particularly
important
for breeding waders on a national
scale
(Smith
1983,
Allport
et al.
1986)
but
there
has been no comprehensive
picture
for
Suffolk.
This paper summarizes the results of a
survey
designed
to
provide
a
detailed
understanding
of the distribution
and densities
of all species of breeding
waders and wildfowl
on saltmarsh
and wet Grassland
bordering
the
Suffolk
estuaries.
The survey will also enable
an assessment
of the relative
importance
of
this region in a national
perspective.
the estuaries
was also surveyed as well as areas
of
shingle
The location
(principally
Orfordness)
and reed.
of these habitats
was delineated
on
1:10,000
maps for collecting
field
data.
In
total
there
were 76 plots
ranging
from 5.3
hectares
to 219 hectares.
Many of these
areas
were distinct
from one another
(see Figure
1) .
Those
stretches
of estuary
between these
plots
were surveyed using 1:25 000 scale field
maps.
Recording
was focused on waders
and wildfowl,
but surveyors were asked to include all species
likely areas.
to attempt to breed within the outlined
The survey method employed
was that
devised by Green et al.
(1984).
Five visits
were made during the breeding
season,
between
April
and
early
June.
Each
plot
was
sub-divided
into areas of homogeneous
habitat
type and management and a route,
which was
repeated
on each visit,
was devised
that
approached
every
point to within
100 metres.
Visits
were not carried
out in windy or rainy
conditions.
For
each visit
the number
and
location
of every bird was recorded
cn the field
maps, noting
obvious pairs,
singing
birds,
birds with young and flocks.
At the end of each
visit
information
from the maps was translated
onto a Summary Table for analysis.
Analysis of field data
Redshank.
The
mean
recorded
before
the
those birds
behaving
flocks,
was taken as
with nests.
of 1st as the
the
total
Redshank
of June,
excluding
if with young or in
peak number of pairs
Snipe.
The maximum number of drumming
or
chipping
birds on any one count was
taken
as
the number of breeding pairs,
so long as birds
were present
throughout
April and early
May.
Birds drumming or chipping on only one date,and
not observed on following
visits,
were noted as
possiblebreeders
but not included in the final
data.
All other species.
The maximum number of birds
recorded
on any one date,
excluding
those in
flocks,
was divided by 2 to give the maximum
number of pairs likely
to be breeding.
This
method
does
not
differentiate
between
non-breeding
and breeding pairs
(for example
Shelduck),
both of which are
included
in the
total breeding pairs recorded (Table 2).
If a
single
bird
or pair of birds was observed
in
suitable breeding habitat on only one occasion
it was recorded
as a possible
breeder
but not
included
in the
summary presented
in this
paper.
METHODS
Survey
The survey covered all areas of saltmarsh
within
Suffolk
and on the south
side of the Stour (the
south bank of the Stour is in Essex, but for the
purpose of this survey the whole estuary
is
considered as one unit).
Grassland adjacent to
RESULTS AND DISCUSSION
In total 3727 ha were surveyed.
This comprised
1141 ha of saltmarsh,
2183 ha of grassland,
346
ha of shingle and 57 ha of reed (see Table 1).
The number and location
of each species recorded
as breeding within the survey area is given in
Table 2.
Six species
of wader,
seven of
B·L'"Y· TH ALDE
ORWELL STOUR
·
/
Figure 1. Location of survey plots.
Table 1. Distribution Suffolk estuaries.
of habitats surveyed in 1988 for each of the
Estuary Blyth Alde/0re/Butleѕ Deben 0rwell Stour total area surveyed (ha)
% of Saltmarsh 9.1 42.4 29.7 8.2 11.7
total area Grassland 25.4 47.0 14.6 9.3 4.3
of habitat Shingle 6.0 78.0 0.5 1.5 14.0
type Reed 15.0 60.0 25.0 0.0 0.0
1141
2183
346
57
Total area surveyed (ha) 688 1806 667 294 273 3727
National Perspective
Smith
(1983) identified
the coastal marshes
of
East Anglia
and north
Kent as
being
particularly
important for breeding Redshank,
Lapwing and Oystercatcher.
The present survey
has shown the study area to hold 1.44 of
the
Redshank and 1.44 of the Oystercatcher
estimated
to breed in Great Britain
(based on population
estimates
reported
by Piersma
1986).
Whilst
these species breed in other areas of Suffolk it
is probable that the majority are within the
coastal
region included in the study area.
By
contrast Lapwings are widespread throughout
the
county and those found within the study area
therefore
represent
only a fraction
of the
county's breeding population.
Nonetheless
the
241 pairs
recorded
represent
0.14 of
the
lapwing estimated
to breed in Great Britain
and
124 of the Suffolk
population
(based on figures
reported
by Wright 1988).
For Ringed Plover
1.04 of the British,
and 0.74 of the European
temperate
population
is
represented
in the
study area (based on figures 1986).
reported
by Piersma
In Britain breeding Avocets are restricted
to
East Anglia with strongholds
predominantly
on
nature
reserves.
Approximately
354 of the
British
population were recorded in the study
area (A.J.Prater,
pers.comm.).
Trends in Breeding Populations
Nine of the plots surveyed in 1988 were visited
during the 1981/82 Breeding Waders of Wet
Meadows survey (Smith 1983). During this period
these
plots
have experienced
an overall
decrease in the populations
of Redshank (- 384),
and Oystercatcher
(- 124), and an increase
in
breeding Lapwing (+ 304) (O'Brien 1989).
It is
too early to assess whether these trends are due
to
natural
fluctuations
in
breeding
populations,
changes in management, or part of
a general decline.
Table 2. Total breeding pairs of waders, wildfowl, gulls and terns for each
of the Suffolk estuaries
in 1988.
Species
Blyth
Canada Goose Branta canadensis
11
Shelduck Tadorna tadorna
72
Gadwall ·nas strepera
15
Teal ·nas crecca
10
Mallard ·nas platyrhynchos
103
Shoveler ·na$ clypeata
21
Tufted Duck ·ythya fuligula
6
0ystercatcher Haematopus ostralegus
30
Avocet Recurv·rostra
avocetta
*
Ringed Plover Ѕharadr·us h·at·cula
22
Lapwing Vanellus vanellus
101
Snipe Gallinago gallOnago
25
Redshank Tr·nga totanus
148
Black-headed Gull Larus r·d·bundus
Common Gull Larus canus
Lesser Black-backed
Gull Larus fuscus
Herring Gull Larus argentatus
Sandwich Tern $terna sandvicensis
Common Tern $terna hitundo
Little
Tern $terna a2bifrons
600 0 0 0 0 1 *
Alde/0re/ Deben 0rwell Burley
55
38
11
202
126
114
15
4
1
2
2
0
115
66
21
27
0
3
64
9
17
223
103
50
*
*
*
24
6
32
89
24
18
0
3
1
120
115
64
592
179
0
30
0
0
7500
0
0
2500
0
0
63
0
0
112
0
0
*
*
*
Stour 10 17 0 0 17 0 0 65 * 16 9 0 14 0 0 0 0 0 0 *
Total 125 531 35 14 322 51 96 471 152 100 241 29 461 1371 30 7500 2500 63 113 98
* Rare British breeding species listed in schedule 1 of the Wildlife and Countryside
Act 1981: locational
details withheld.
Table 3. Distribution of breeding waders on the Suffolk estuaries in 1988. Figures are given as the percentage of total pairs for each species, from Table 2.
Blyth Alde/0re/ Burley Deben 0rwell Stour
Redshank 32% 26% 25% 14% 3%
Lapwing 0ystercatcher
42% 37%
6% 47%
10% 8% 4%
22% 11% 14%
Snipe 86% 0% 10% 4% 0%
Ringed Plover 22% 24% 6% 32% 16%
Ringed Plovers were surveyed in Suffolk in 1979
and 1985 (Piotrowski
1980,
Waters 1985).
Over
this five year period Waters (1985) reported
a
decrease
of
204 in the
overall
county
population.
Orfordness
held
the
largest
discrete
population
with 53 pairs in 1979 and 34
in 1985.
The present survey reported only 13
pairs
to be breeding on Orfordness,
a total
decline
of 754 in nine years.
This decline has
been attributed
to increased
human
disturbance
and the expansion of the Orfordness
gull
colony
(Waters 1985,
1988).
In contrast
the Orwell
population
has increased from 17 pairs in
1985
(Waters 1985) to 32 pairs in 1988, half of which
were on newly created
areas of shingle
at
Fagbury.
These are, however, soon to be lost to
the Felixstowe
Dock development
(see Beardall,
Dryden & Holzer 1988).
Distribution
of Breeding Waders
The distribution
of breeding waders was to a
large
extent
dictated
by the availability
of
suitable
habitat.
For example the Stour held 84
of the
total wader population in 74 of the
study area and the Blyth held 24· of the waders
in 19· of the study area (Tables 1 & 2).
One third
of all Redshank were found on the
Blyth estuary,
predominantly
on
grassland
(Table 3). Over the entire study area, however,
484 were found on saltmarsh and 484 on grazing
marsh, despite
there being twice the area of
grassland
available
(Table
4).
Although
ungrazed
salting
was only 274 of
the study
area,
444 of the redshanks were found to use
this
habitat
with a peak density
of
81
pairs/km2.
This compares favourably with a peak
density
of 78 pairs/km2
reported
in 1985
(Allport
et al.
1986).
On cattle
grazed
grassland
a peak density of 50 pairs/km2
was
recorded.
In comparison with Redshank, Lapwing
only reached a maximum density of 34 pairs/km2,
with the
majority
of birds
found on cattle
grazed grassland.
One would expect to see the area of shingle
on
the Alde/Ore/Butley
(accounting
for 784 of all
shingle
in the study area) to be reflected
in
the
breeding
numbers of Oystercatcher
and
Ringed
Plover.
Whilst
474
of
the
Oystercatchers
were recorded on this estuary,
only 184 nested on shingle
compared with 474 on
saltmarsh and 344 on grassland.
Similarly
the
number of Ringed Plover on each estuary did not
Table 4. Distribution of breeding Redshank on different habitats and management types.
% of area surveyed
% of total prs Redshank
Salting
Cattle grazed
1
1
Sheep grazed
2
2
Cattle and sheep grazed
1
1
Ungrazed
27
44
Total
31
48
Grazing Marsh
Cattle grazed
28
29
Sheep grazed
6
2
Cattle and sheep grazed
2
4
Ungrazed
21
9
Mown
3
4
Total
60
48
Other Habitats
10
5
value of these important
areas.
It will
also
assist in formulating
advice presented
to land
owners
and managers
(e.g.
farmers,
local
government
and water
management
bodies),
providing
the potential
to improve the value of
many
sites
for
breeding
birds.
This
information
is particularly
relevant
in the
light of the designation
in 1988 by the British
Government
of the Suffolk
river valleys
as an
Environmentally
Sensitive Area (ESA), in which
farmers
receive subsidies
in return for using
management practices
that are
sympathetic
to
wildlife.
The grasslands
adjacent to both the
Alde/Ore/Butley
and the Blyth lie within
this
ESA.
The effectiveness
of this designation
in
promoting and maintaining
the wildlife
value of
these
areas will be revealed
by repeating
this
study in future years.
ACKNOWLEDGEMENTS
The authors wish to thank the 21 surveyors
who
kindly
gave up their free time to collect
the
field data,
and the many landowners who gave us
permission
to survey their property.
The Suffolk
Wildlife
Trust Estuaries
Project is funded by
the Central Electricity
Generating Board through
the World Wide Fund for Nature.
reflect
the distribution
of
shingle.
For
example the Orwell, which only accounted for 24
of the shingle in the study area, held 32% of
the Total Population.
Only very small numbers of Snipe were recorded
(Table 2), probably because the soft penetrable
ground required by this species was generally
unavailable
over much of the study area.
The
Blyth estuary held 864 of the total pairs
recorded but only 254 of the grassland in the
study area. During the survey it was noted that
these areas were exceptionally
wet which may
account for the relative
importance
of this
estuary.
Avocets were found to be breeding not only on
saltmarsh
and brackish
lagoons,
but also on
freshwater
grazing marshes.
Distribution
of Gulls
and Terns
The large number of gulls found on the
Alde/Ore/Butley
illustrates
the importance
of
Orfordness as a breeding site.
This colony of
Lesser
Black-Backed
and Herring
Gulls,
with
some Common Gulls,
is one of the
largest
in
south-east
England and accounts for 154 of the
North Sea population of Lesser Black-Backed
Gulls
(Tasker
et al.
1987).
The main
Black-Headed
Gull colonies
were found on areas
of saltmarsh on the Deben, Blyth and Butley.
Most of the Common
Terns were recorded
owned and managed
Protection
of Birds.
Terns and all on Hayergate by the Royal
of the Island, Society
Sandwich an area for the
Conservation
The present survey was undertaken primarily
to
provide
a detailed
understanding
of the
distribution
and abundance of breeding
waders
and wildfowl
on and adjacent to the Suffolk
estuaries.
During the spring of 1989 all
remaining areas of coastal grazing marsh will be
surveyed,
providing
a complete picture
of
breeding waders and wildfowl
in the coastal
region.
The information
collected
during
the present
survey provides a comprehensive
baseline
from
which
future
comparable
surveys
can
gauge
changes in breeding populations as well as in
land use and management.
The data forms an
essential
conservation
tool,
allowing
informed
arguments to be presented against insensitive
development
proposals
which may degrade the
REFERENCES
Allport,
G., O'Brien,
M. & Cadbury, C.J.
Survey of redshank and other breeding
on saltmarshes
in Britain
1985.
Society for the Protection
of Birds
Sandy.
1986. birds Royal (RSPB),
Beardall,
C.H.,
Dryden,
R.C. & Holzer,
T.J.
1988.
The Suffolk Estuaries.
A report
by
the Suffolk
Wildlife
Trust
on the
Wildlife
and Conservation
of the Suffolk
estuaries.
Suffolk
Wildlife
Trust,
Saxmundham.
Green, R.E., Johnson, T. & Collins,
D. 1984.
An
intensive
survey of breeding
redshank
on
the Wash. Unpublished
report,
RSPB.
O'Brien,
M. 1989. Breeding waders of wet meadows
survey, 1989. BTO News 161: 7.
Piersma,
T. 1986.
Breeding
Wader Study Group Bull.48,
Waders in Europe. Suppl.
Piotrowski, Survey Bulletin
S. 1980.
1979. Suffolk
No.43:
1-9.
Suffolk
ringed
Ornithologists'
plover Group
Smith, K.W. 1983. The
waders breeding
in England
and
177-192.
status on wet Wales.
and distribution
of
lowland
grasslands
Bird Study 30:
Tasker, M.L., Webb, A., Hall, A.J.,
Pienkowski,
M.W. & Langslow, D.R. 1987. Seabirds in the
North Sea. Final report of phase 2 of the
NCC Seabirds
at Sea
Project.
Nature
Conservancy Council, Peterborough.
Waters,
R. 1985. BTO breeding
ringed
survey 1985. Suffolk Ornithologists'
Bulletin
68: 12-18.
plover Group
Waters, R. 1988. Ringed plovers
West, R.B. & Wright, M.T.
Estuaries
Report 1988, pp
BOEE
co-ordinators.
in Suffolk.
In:
(eds.),
Suffolk
22-·4.
Regional
Wright,
M.T. 1988. 1987 survey
lapwings
in
Suffolk.
Ornithologists'
Group Bulletin
of nesting Suffolk 79: 24-25.
T.J. Holzer,
C.H. Beardall
& R.C.
Suffolk
Wildlife
Trust,
Park
$axmundham, Suffolk,
U.K.
Dryden, Cottage,

TJ Holzer, CH Beardall, RC Dryden

File: breeding-waders-and-other-waterfowl-on-suffolk-estuaries-in-1988.pdf
Title: BREEDING WADERS AND OTHER WATERFOWL ON SUFFOLK ESTUARIES IN 1988
Author: TJ Holzer, CH Beardall, RC Dryden
Author: T. J. Holzer , C. H. Beardall , R. C. Dryden
Published: Mon Jan 28 13:48:14 2008
Pages: 4
File size: 0.44 Mb


The Truth About EIFS, 3 pages, 0.02 Mb

MEDIEVAL MUSIC, 30 pages, 0.35 Mb

, pages, 0 Mb
Copyright © 2018 doc.uments.com