Report 575
An assessment of the numbers and distributions of little gull Hydrocoloeus minutus and great cormorant Phalacrocorax carbo over winter in the Outer Thames Estuary
(2015)
Lawson J., Kober, K., Win, I., Allcock, Z., Black, J., Reid, J.B., Way, L. & O’Brien, S.H.
This report collates five winter seasons of aerial survey data (2003/04, 2004/05, 2005/06, 2006/07, 2007/08) were analysed using distance sampling methods. The means of the highest counts from each winter (mean of peak) were used to define the size of the population of each species in the Outer Thames Estuary, as is standard practice deriving from the Ramsar convention. The numbers of little gull and great cormorant were assessed against the UK SPA selection guideline thresholds (Stroud et al 2001).
 

Introduction

 

Directive 2009/147/EC of the European Parliament and the Council of 30 November 2009 on the conservation of wild birds (this is the codified version of Directive 79/409/EEC as amended) requires EU member states to identify as Special Protection Areas (SPAs) the most suitable territories on land and at sea for species listed on Annex I of the Directive and regularly occurring migratory species. To identify inshore areas that might be suitable for SPA classification, 45 areas of search were selected where potentially important numbers of waterbirds congregate outside the breeding season. The Outer Thames Estuary was one of these, as it is known that seabirds and waterbirds use the area during winter. In 2010 part of the Outer Thames Estuary area of search was classified as an SPA to protect wintering red-throated diver (O’Brien et al 2012). Additional intertidal SPAs fringing the Outer Thames Estuary area provide protection for a variety of bird features above mean low water.

Natural England advises the UK Government of the most suitable areas for classification as SPAs in UK territorial waters adjacent to England (within 12nm). The aim of this report is to provide Natural England with the evidence necessary to support its advice to the UK Government on the relative importance of the Outer Thames Estuary area in a UK context for little gull Hydrocoloeus minutus and great cormorant Phalacrocorax carbo over winter.

Population estimates for little gull and great cormorant in the Outer Thames Estuary during winter are provided. Other waterbird and seabird species, individually or as an assemblage, did not occur in numbers that exceeded the thresholds under the UK SPA Guidelines (Webb et al 2009).

 
 
ISSN 0963-8901
 
Please cite as: Lawson J., Kober, K., Win, I., Allcock, Z., Black, J., Reid, J.B., Way, L. & O’Brien, S.H., (2015), An assessment of the numbers and distributions of little gull Hydrocoloeus minutus and great cormorant Phalacrocorax carbo over winter in the Outer Thames Estuary, JNCC Report 575, ISSN 0963-8901