Eared grebes (Podiceps nigricollis) are colonial-nesting waterbirds that breed in Canada and northern United States. Great Salt Lake (GSL), Utah, is vital to the survival of this species because all eared grebes in North America stage in the fall either on the GSL or Mono Lake, California. The importance of GSL and its surrounding wetlands for breeding eared grebes is unknown. We studied eared grebe nesting status and chronology in the freshwater wetlands around GSL and found over 4,280 nests distributed among 35 colonies during 2018 and 5,794 nests among 23 colonies during 2019. We also located the 2 largest colonies of this species ever recorded (902 and 1,492 nests). Mean clutch size differed between years and was 2.4 eggs during 2018 and 2.0 during 2019; clutch sizes were lower at GSL than in colonies located in more northern latitudes, perhaps due to a local paucity of invertebrate prey during the egg-laying period. Grebe nests around the GSL were constructed with, and anchored to, growing Stuckenia pectinate. Eared grebes near GSL started laying eggs in the first week of June during 2018 and a week later during 2019. The number of incubated nests per colony peaked on 27 June during 2018 and 9 July during 2019. Nests continued to be incubated into August in both years. These dates are later than those reported in more-northern colonies. The later nesting in GSL colonies could be due to the birds' need to wait for Stuckenia pectinata to form mats at the water surface. This plant species needs a water depth of 38 to 45 cm to thrive, and increasing amounts of freshwater from the GSL watershed are diverted for agriculture and human development. If this trend continues, there may not be enough water to maintain the required water depth for dense stands of Stuckenia; the loss of which may prevent the grebes from nesting. © 2021 The Wildlife Society.

中文翻译：

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犹他州大盐湖沿岸有耳鸷的筑巢状况和年代

有耳鸷（Podiceps nigricollis）) 是在加拿大和美国北部繁殖的殖民地筑巢水鸟。犹他州的大盐湖 (GSL) 对该物种的生存至关重要，因为北美的所有有耳鸬鹚都会在秋季在 GSL 或加利福尼亚的莫诺湖上活动。GSL 及其周围湿地对繁殖有耳鸷的重要性尚不清楚。我们研究了 GSL 周围淡水湿地的耳鸮筑巢状况和年代，发现 2018 年分布在 35 个群体中的 4,280 个巢穴和 2019 年分布在 23 个群体中的 5,794 个巢穴。我们还找到了该物种有史以来最大的两个群体（902 个和 1,492 个）巢）。平均离合器大小因年份而异，2018 年为 2.4 枚，2019 年为 2.0 枚；GSL的离合器大小低于位于更北纬度的殖民地，可能是由于产卵期间当地缺乏无脊椎动物猎物。GSL 周围的 Grebe 巢穴建造并锚定在生长Stuckenia 果胶。GSL 附近的有耳鸬鹚在 2018 年 6 月的第一周和一周后的 2019 年开始产卵。每个群体的孵化巢穴数量在 2018 年的 6 月 27 日和 2019 年的 7 月 9 日达到顶峰。两个国家的巢穴继续孵化到 8 月年。这些日期比在更北的殖民地报告的日期晚。后来在 GSL 群体中筑巢可能是由于鸟类需要等待Stuckenia pectinata在水面上形成垫子。这种植物物种需要 38 到 45 厘米的水深才能茁壮成长，并且越来越多的来自 GSL 流域的淡水被转移用于农业和人类发展。如果这种趋势继续下去，可能没有足够的水来维持Stuckenia密集林分所需的水深；失去它们可能会阻止鲱鱼筑巢。© 2021 野生动物协会。