Gray seals were historically distributed along the northeastern coast of the United States, but bounties and lack of protection reduced numbers and they were rarely observed for most of the 20th century. Once protections were enacted, the population started to rebound. Here, we describe the recolonization and recovery of gray seals in the United States, focusing on the re-establishment of pupping sites. We fit individual generalized linear models to various time series (1988–2019) to estimate rates of increase in observed pup counts at four of the more data-rich sites. Annual rate of increase at individual sites ranged from –0.2% (95% CI: –2.3–1.9%) to 26.3% (95% CI: 21.6–31.4%). The increase in sites and number of pups born in the United States is driven by population growth and immigration from Canadian colonies and is part of a larger recovery of the Northwest Atlantic population. Wildlife protection, a healthy source population, habitat availability, and species traits that allow for dispersal and high productivity were all important factors in this recovery.

中文翻译：

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1988 年至 2019 年在美国重新定殖地点幼崽的灰海豹（Halichoerus grypus atlantica）的增长率

灰海豹历史上分布在美国的东北海岸，但赏金和缺乏保护减少了数量，并且在 20 世纪的大部分时间里很少观察到它们。一旦制定了保护措施，人口就开始反弹。在这里，我们描述了美国灰海豹的重新定殖和恢复，重点是重建幼崽场所。我们将单个广义线性模型拟合到各种时间序列（1988-2019），以估计在四个数据更丰富的站点观察到的幼崽数量的增长率。个别地点的年增长率范围从 –0.2%（95% CI：–2.3–1.9%）到 26.3%（95% CI：21.6–31.4%）。在美国出生的幼崽的地点和数量的增加是由人口增长和来自加拿大殖民地的移民推动的，并且是西北大西洋人口更大规模恢复的一部分。野生动物保护、健康的来源种群、栖息地可用性以及允许分散和高生产力的物种特征都是这种恢复的重要因素。