This report describes the fluctuations in the numbers of breeding pairs in the Special Protected Area under the Bird Directive ‘Kustbroedvogels te Zeebrugge‐Heist’ and in the adjacent western port of Zeebrugge during the period 1985‐2017. Until recently, this was by far the most important breeding site for coastal breeders in Belgium and of high importance for the European tern populations as a whole. The conservation targets that were set in 2004 (being 22 ha of suitable nesting habitat without significant impact by land predators) for terns breeding in the Special Protected Area were never met since.The populations of the 3 tern species (Sandwich, Common and Little Tern) and of Black‐headed Gulls breeding in the Special Protected Area have strongly declined after 2008 and the reproductive output was extremely poor. The decline is due to the presence of land predators, initially cats and rats, and from 2009 onwards also fox. The maximum number of breeding pairs amounted to 4,067, 3,052 and 425 for Sandwich, Common and Little Tern, respectively, but in 2016 these species no longer bred in the SPA. In 2017 fox was no longer present and the area again hosted 576 pairs of Common Tern, 21 pairs of Lesser Black‐backed Gull, 1 pair of Mediterranean Gull, 2 pairs of Kentish Plover , 12 pairs of Ringed Plover and 16 pairs of Oystercatcher. The SPA also attracted 114 pairs of Lesser Black‐backed and 44 pairs of Herring Gulls that were actively chased away in the nearby western part of the Zeebrugge port. Some of them developed into specialised predators of Common Tern leading to a reproductive output of only 0.1 fledged chick per pair.Also in the non‐protected western part of the Zeebrugge port, breeding numbers are in strong decline due to fox disturbance and predation, and loss of breeding grounds and deterioration of the habitat. Crested Lark, Northern Wheatear, Mediterranean Gull and Yellow‐legged Gull used to breed in small numbers, but these species were no longer present in 2016. This area used to host large numbers of Herring Gulls (max 2,433 pairs in 2010) and Lesser Black‐backed Gulls (max 4,760 pairs in 2011), but both species strongly decreased in numbers as fox frequented the breeding site after 2013. In 2017, 516 pairs of Herring Gull and 1.326 pairs of Lesser Black‐backed Gull bred in Zeebrugge, the majority (65.9%) on fox‐free rooftops. After 2013 the numbers of Herring and Lesser Black‐backed Gull have increased elsewhere in Flanders and especially along the coast the number of breeding sites is rapidly growing. This suggests that part of the Zeebrugge colony has moved to both new and existing breeding sites. Indeed, recoveries of colour‐ringed individuals revealed that there is a strong connection between Zeebrugge and other breeding sites along the Flemish coast. Other ringed gulls originating from Zeebrugge moved to existing colonies in the north of France, the south of the Netherlands and the south‐east of the UK. |
