|BRITISH TRUST FOR ORNITHOLOGY SURVEYS
Harry Green BTO Regional Representative in Worcestershire
Following on from the dreadful year of Foot & Mouth Disease 2001 which completely disrupted fieldwork, 2002 has been a reasonably good year. Most of the Breeding Bird Survey 1 km squares were surveyed, the Waders in Wet Meadows survey was completed with considerable extension into a complete survey of the Avon and Severn flood plains. Several Water Bird Breeding Surveys were done. In all a lot of good data was collected in Worcestershire. Very many thanks to all volunteer surveyors who plodded lonely transects, some in virtually bird-free farmland.
BREEDING BIRDS SURVEY
|WATERWAYS BREEDING BIRDS SURVEY
(WBBS) AND WATERWAYS BIRD SURVEY (WBS)
are five WBBS's running in Worcestershire: two on the
River Teme, one on the Worcester-Birmingham Canal at
Worcester, another on the canal near Alvechurch, and one
on Dowles Brook in Wyre Forest. This survey is uses
similar transect methodology to the BBS and most of the
sites have been randomly selected using 1 km squares.
Nationally the survey provides data on many water birds
which might otherwise be less frequently encountered by
the BBS. There is an expectation that this survey will be
expanded so there may be more sites requiring surveyors
in the future. The 1 km squares surveyed in
Worcestershire are SO7778 (Dowles Brook), SO6466 and SO7454
(Teme) SO8757 (Worcester canal), SP0270 (canal at
This very-long running national survey (the longest continuous bird survey in the world!) is of course continuing with annual counts of nests at many heronries. We have two in Worcestershire by the river Severn - one north and one south of Worcester. The survey in Worcestershire is undertaken by Shaun Micklewright. Nationally the coverage by annual counts is patchy and every so often BTO has organised a more complete survey aiming to count all heronries on a national scale including more remote places such a rocky coasts and islands. The last major census was in 1985. 2003 is the 75th year of the annual counts and has been chosen for a new complete census of all heronries in UK. Herons have done well in recent years. Less persecution, more protection and a run of mild winters have helped, and there has been a considerable improvement in river quality. The 2003 census could show herons at an all time high. However, there are concerns about more insidious pollution: there have been well-documented cases of herons producing significant numbers of deformed young in some seasons, without, as yet, any explanation. Within the heron food chain fish have been affected by low levels of contraceptive chemicals in cleaned-up sewage, and in more remotely sited fish farms herons are eating fish containing antibiotics. The value of detailed surveys of herons, at the top of an aquatic food chain, is that changes in their population levels may reveal serious un-seen pollution problems. Monitoring herons could lead to better care as it did for the used of certain farm pesticides 40 years ago.
Locally we are unaware of any other than our two main heronries near Worcester, but there may be others with just a few nests, or even solitary nesters we do not know about. Full details of the methodology for the 2003 survey are not yet available but the survey will probably fall into three parts:
Counts of known and newly reported heronries
A search of random squares for missed sites
Detailed study of sample of sites throughout the breeding season.
I should be very pleased to hear of any nesting herons away from the main sites either in the past few years or next year. Herons do of course start nesting very early in the New Year, often during February and March. If you would like to help please contact me.
THE NEXT ATLAS OF BIRD DISTRIBUTION
Although 2002 was not an official BTO survey year we are very keen to keep track of Nightingales in Worcestershire. To this end a Press Release was sent out and from this and other publicity a few records were received. I am not sure that all records came my way so if anyone has additional records I would be please to receive them.
Old railway line south of Broadway (Peasebrook Farm, Broadway Sewage Works, Little Buckland) 4 or 5 singing birds
Wormington Brake: one.
Castle Morton Common: one bird
Langdale Wood: three.
Croome park/old airfield: one.
Drakes Broughton (Dufty Coppice, Mill Lane): probably four
Marsh Common, Baughton: only one
Strensham Islands/waterworks: two
Upton on Severn: one
Stourport on Severn: one
Evesham: two reports of birds singing near the river Avon in centre of Evesham
Most of these records are from well-known sites. There does seem to have been more birds along the old railway near Broadway. Much of this contains scrub and a closer look along a considerable length of it north and south of Broadway could prove interesting in 2003. The records from Evesham are unusual and need following up in 2003. Birds N of Stourport could be associated with the record of a bird which sand near Burlish Top in previous years. There have apparently been fewer records from the Croome area in 2002 but this could simply be because no-one listened!
Thus, there are about 20-25 records for 2002 and if this is correct the documented decline has continued. (see earlier numbers of Worcestershire Record)
The results and analysis of the national 1999 survey have now been published (Wilson AM et al 2002). The authors' summary of the survey is as follows. 3000 sites surveyed in 1980 were surveyed again by volunteers between mid April and early June 1999. 135 randomly selected tetrads were also surveyed to gauge the success of the volunteer survey. The main survey located 4565 singing males, and the random tetrad results suggested that a further 32% of birds occurred away from the surveyed sites, indicating a probable national population of about 6700 males. A higher proportion (46.7%) of nightingales were found in scrub in 1999 compared with the 1976 survey (28.4%). Overall, the survey indicated that similar numbers of nightingales were found in both the 1980 and 1999 surveys although earlier surveys probably under estimated numbers. However, the range has contracted markedly over the last few decades and numbers outside the core areas in SE England are low. Changes in habitat quality and an increasing deer population have caused decreases on a local scale by removal of suitable woodland under-storey. Changes in climate on the breeding grounds and general changes in global climate and suitability of habitat in African wintering grounds are also likely to be important in altering the English breeding population . Models of future climatic change in Britain predict that numbers and range of nightingales should increase in the next few decades as warming occurs but this is also dependent on countryside management and the impact of leisure activities on suitable habitat.
Although the overall trend in the mean April to June temperature in central England has gradually increased since 1900 the increase has been irregular in pattern. For instance, temperature peaked in the 1940s, decreased between the early 1960s and mid 1980s, and has increased again since then. Nightingale population changes appear to follow this pattern, but because the present period of amelioration has been relatively short, perhaps population numbers and range have not yet responded to improved conditions. However, wet cool weather in spring , despite warmer overall conditions, may be unsatisfactory for nightingales. What is apparent is that we should continue to monitor nightingales in Worcestershire because, if expansion of range occurs, we shall probably be some of the first to see it - if suitable breeding habitat is available. Nightingales require suitably structured scrub both outside and in woods. High numbers of deer may prevent it developing in woods, and present agriculture is not scrub-friendly, although farm Stewardship Schemes may result in some suitable hedges.
WILSON, AM, HENDERSON ACB & FULLER RJ 2002. Status of nightingale Luscinia megarhynchos in Britain at the end of the 20th century with particular reference to climate change. Bird Study 49, 193-204.
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