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<p>The lower River Elbe, including Hamburg, is part of a distribution hotspot for Mediterranean Gulls in northwest Europe. We studied local population trends and foraging behaviours of 13 adult Mediterranean Gulls breeding on a roof top at the edge of Hamburg city in June 2021 and 2022, using GPS tagging. Mediterranean Gulls have bred regularly in the Hamburg region since 1987, increasing to around 150 pairs at the end of the 2000s. After 2019, breeding numbers increased to &gt; 300 pairs, with frequent changes among three local colonies. In both 2021 and 2022, most foraging trips were directed towards the south and southeast, but Mediterranean Gulls also regularly performed long-distance trips heading west and northwest. Foraging trips lasted up to 59.2&#xa0;h, with foraging ranges up to 115.2&#xa0;km and total distances covered in the foraging trips ranging from 3.0 to 514.2&#xa0;km. The most important foraging habitats were pastures (mean 62%) and non-irrigated arable land (mean 26%). Nine of the 11 analysed Mediterranean Gulls showed prospecting behaviour. The longest prospecting periods per individual lasted between 2.2 and 11.1&#xa0;h (mean 5.4&#xa0;h). At the end of their individual breeding periods, only one of the 11 birds left the Hamburg-Moorfleet colony on long-distance migration, while all the other individuals stopped in at least one other colony in northern Germany for a few days. Mediterranean Gulls in northern Germany are characterised by spatially variable breeding site locations, coinciding with a high level of prospecting behaviour. In contrast, the use of foraging habitats seems to be consistent, including local and traditional foraging sites.</p>

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Urban life of an elusive species: population trends, movement patterns, foraging habitats, and prospecting in Mediterranean Gulls (Ichthyaetus melanocephalus) breeding in Hamburg, northern Germany

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  • 发表日期：

    2025年1月6日

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  • Stefan Garthe,
  • Karena Haecker,
  • Alexander Mitschke,
  • Volker Dierschke,
  • Philipp Schwemmer

摘要

The lower River Elbe, including Hamburg, is part of a distribution hotspot for Mediterranean Gulls in northwest Europe. We studied local population trends and foraging behaviours of 13 adult Mediterranean Gulls breeding on a roof top at the edge of Hamburg city in June 2021 and 2022, using GPS tagging. Mediterranean Gulls have bred regularly in the Hamburg region since 1987, increasing to around 150 pairs at the end of the 2000s. After 2019, breeding numbers increased to > 300 pairs, with frequent changes among three local colonies. In both 2021 and 2022, most foraging trips were directed towards the south and southeast, but Mediterranean Gulls also regularly performed long-distance trips heading west and northwest. Foraging trips lasted up to 59.2 h, with foraging ranges up to 115.2 km and total distances covered in the foraging trips ranging from 3.0 to 514.2 km. The most important foraging habitats were pastures (mean 62%) and non-irrigated arable land (mean 26%). Nine of the 11 analysed Mediterranean Gulls showed prospecting behaviour. The longest prospecting periods per individual lasted between 2.2 and 11.1 h (mean 5.4 h). At the end of their individual breeding periods, only one of the 11 birds left the Hamburg-Moorfleet colony on long-distance migration, while all the other individuals stopped in at least one other colony in northern Germany for a few days. Mediterranean Gulls in northern Germany are characterised by spatially variable breeding site locations, coinciding with a high level of prospecting behaviour. In contrast, the use of foraging habitats seems to be consistent, including local and traditional foraging sites.