The ivory gull Pagophila eburnea is a high-Arctic seabird associated with sea ice throughout the year. It breeds at high latitudes, mostly in the Atlantic sector of the Arctic. It is rare (<11 500 breeding pairs globally) and remains one of the most poorly known seabirds in the world. Al though Svalbard (Norway) supports breeding populations of international significance, the population trend in the region was unknown prior to this study. We conducted annual surveys of known breeding sites from 2006 to 2019 to estimate the size of the ivory gull population in Svalbard and to assess the population trend. We visited 117 colonies, 60 of which were new discoveries during this study. All breeding sites were situated in cliffs, and no ground-breeding ivory gulls were found. Based on the most complete survey in 2019, we estimated the Svalbard breeding population to be between 1500 and 2000 breeding pairs. We recorded an overall 40% decline in the number of breeding ivory gulls, but the trends varied significantly among colonies. The interannual fluctuations in the number of breeding pairs were not synchronous among colonies, which can be explained by the movements of adult breeding birds between colonies. The current de cline in the Svalbard ivory gull population could be related to the ongoing decline in sea ice extent and quality in the Barents Sea. It may also be driven by ecological changes along the migration routes or at the wintering grounds, as hypothesized for the Canadian breeding population.

中文翻译：

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斯瓦尔巴群岛受威胁象牙鸥Pagophila eburnea种群现状及趋势

象牙海鸥 Pagophila eburnea 是一种全年都与海冰有关的高北极海鸟。它在高纬度地区繁殖，主要在北极的大西洋地区。它是罕见的（全球小于 11 500 对繁殖对）并且仍然是世界上最鲜为人知的海鸟之一。尽管斯瓦尔巴群岛（挪威）支持具有国际意义的繁殖种群，但在本研究之前，该地区的种群趋势尚不清楚。我们从 2006 年到 2019 年对已知的繁殖地进行了年度调查，以估计斯瓦尔巴群岛象牙鸥种群的规模并评估种群趋势。我们访问了 117 个菌落，其中 60 个是本研究中的新发现。所有繁殖地都在悬崖上，没有发现地面繁殖的象牙海鸥。根据 2019 年最完整的调查，我们估计斯瓦尔巴群岛的繁殖种群在 1500 到 2000 对繁殖对之间。我们记录到繁殖象牙海鸥的数量总体下降了 40%，但不同殖民地之间的趋势差异很大。种群间繁殖对数的年际波动并不同步，这可以通过种群间成年种鸟的运动来解释。目前斯瓦尔巴群岛象牙鸥种群的下降可能与巴伦支海海冰范围和质量的持续下降有关。它也可能是由沿迁徙路线或越冬地的生态变化驱动的，正如对加拿大繁殖种群的假设。但各殖民地之间的趋势差异很大。种群间繁殖对数的年际波动并不同步，这可以通过种群间成年种鸟的运动来解释。目前斯瓦尔巴群岛象牙鸥种群的下降可能与巴伦支海海冰范围和质量的持续下降有关。它也可能是由沿迁徙路线或越冬地的生态变化驱动的，正如对加拿大繁殖种群的假设。但各殖民地之间的趋势差异很大。种群间繁殖对数的年际波动并不同步，这可以通过种群间成年种鸟的运动来解释。目前斯瓦尔巴群岛象牙鸥种群的下降可能与巴伦支海海冰范围和质量的持续下降有关。它也可能是由沿迁徙路线或越冬地的生态变化驱动的，正如对加拿大繁殖种群的假设。目前斯瓦尔巴群岛象牙鸥种群的下降可能与巴伦支海海冰范围和质量的持续下降有关。它也可能是由沿迁徙路线或越冬地的生态变化驱动的，正如对加拿大繁殖种群的假设。目前斯瓦尔巴群岛象牙鸥种群的下降可能与巴伦支海海冰范围和质量的持续下降有关。它也可能是由沿迁徙路线或越冬地的生态变化驱动的，正如对加拿大繁殖种群的假设。