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Seaduck survey programme

 

Background and rationale of surveys
JNCC’s Seabirds At Sea Team (SAST) has run an annual survey programme of inshore waters since the winter of  2000/01, primarily using aerial surveys.  The aim of these surveys is to collect up-to-date, detailed data on the numbers and distribution of wintering aggregations of seaduck, divers and grebes. The surveys currently contribute to two strands of work; (1) identification of inshore areas used by non-breeding aggregations of marine waterbirds under the Marine Natura 2000 Project and (2) monitoring populations of marine waterbirds under the  African-Eurasian Migratory Waterbird Agreement (AEWA).
 
Sampling methods
Most surveys are conducted from small aircraft.  Aerial surveys are a suitable method to identify areas with important inshore bird aggregations, as large and sometimes inaccessible areas can be surveyed in a short space of time.  This minimises costs and reduces the risk of double counting birds by completing the survey in as short a time as possible.  A line-transect sampling method is used which allows the use of distance sampling to calculate more accurate population estimates. The sampling method also allows bird distribution data to be collected at a very fine spatial scale. The line-transect method used by the SAST is based upon that developed in Denmark by the National Environmental Research Institute (NERI), and a full description of the methods used can be found in Dean et al. (2003).  Some species, such as grebes, cannot be adequately surveyed using aerial surveys, and so in some areas aerial survey data are supplemented by data from land-based or boat-based surveys. 
 
Current status/work
JNCC in conjunction with the four country nature conservation agencies (CCW, CNCC, NE and SNH)  has compiled a list of 45 inshore areas that are likely to be important for non-breeding inshore waterbirds. This list of inshore areas is being used to inform the annual survey programme and to date, data have been collected in at least 29 of these areas either by the JNCC (mainly Scottish sites), or the Wildfowl and Wetlands Trust in collaboration with JNCC (other UK sites).
 
Data from these surveys are currently being analysed to calculate the numbers of marine waterbird species wintering in important inshore areas, and to determine their distribution within these areas. The results of these analyses enable JNCC to provide advice to the country agencies in identifying those inshore areas that meet UK Special Protection Area (SPA) guidelines. Based on this work, the first wholly marine SPA was designated by CCW in 2003, for wintering common scoter in Bae Caerfyrddin/Carmarthen Bay (Wales).
 
Data obtained from aerial surveys are also of use in assessing UK population sizes for some species.  To date, these data have been used to re-assess the British wintering population size of red-throated divers.  Previously the best estimate for this species was 5,000, but WWT aerial surveys highlighted the inaccuracy of this when they observed up to 11,000 individuals in just one area (the Greater Thames).  The newly revised estimate of the wintering population of this species, based largely on aerial survey data, is now in the region of 17,000 birds (O'Brien et al. in press).
 
Available outputs
 
Aerial surveys
Data collected by aerial surveys are summarised in the following reports.  More detailed survey data are available on request from the JNCC.
 

Lewis, M., Wilson, L.J., Söhle, I., Dean, B.J., Webb, A. and Reid, J.B. (2008). Wintering sea ducks, divers and grebes in UK inshore areas: Aerial surveys and shore-based counts 2006/07. JNCC Report, No. 414

 
Dean, B.J., Webb, A.W., McSorley, C.A. and Reid, J.B. (2003). Aerial surveys of UK inshore areas for wintering seaduck, divers and grebes: 2000/01 and 2001/2.  JNCC Report No.333
 
Dean, B.J., Webb, A.W., McSorley, C.A. and Reid, J.B. (2004). Surveillance of wintering seaduck, divers and grebes in UK inshore areas: Aerial surveys 2002/03. JNCC Report No. 345
 
Dean, B.J., Webb, A.W., McSorley, C.A. Schofield, R.A and Reid, J.B. (2004). Surveillance of wintering seaducks, divers and grebes in UK inshore areas: Aerial surveys and shore-based counts 2003/04. JNCC Report No. 357
 
Wilson, L.J., Dean, B.J., Webb, A.W., McSorley, C.A. and Reid, J.B. (2006). Wintering seaducks, divers and grebes in UK inshore areas: Aerial surveys and shore-based counts 2004/05. JNCC Report No. 371
 
Söhle I., Wilson L.J., Dean B.J., O'Brien S.H., Webb A. and Reid J.B. (2006) Surveillance of wintering seaducks, divers and grebes in UK inshore areas: Aerial surveys and shore-based counts 2005/06. JNCC Report No. 392
 
Lewis M., Wilson L.J., Söhle I., Dean B.J., Webb A. and Reid J.R. (2008).  Surveillance of winter and spring aggregations of seaducks, divers and grebes in UK inshore areas: Aerial surveys and shore-based counts 2006/07. JNCC Report No. 414
 
Analysis of aerial survey data
McSorley C.A., Webb A., Dean B.J., Reid J.B. (2005) UK inshore Special Protection Areas: a methodological evaluation of site selection and definition of the extent of an interest feature using line transect data.  JNCC Report No. 344
 
Revised estimate of wintering red-throated divers
O'Brien S.H., Wilson L.J., Webb A. & Cranswick P.  (in press) Revised estimate of numbers of wintering red-throated divers Gavia stellata in Great Britain.  Bird Study
 
 
 
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