Double‐crested cormorants (Phalacrocorax auritus) and great egrets (Ardea alba) have an extensive history of human‐wildlife conflict with the aquaculture industry of western Mississippi, USA, due to their depredation of cultured catfish (Ictalurus spp.). Although aquaculture is abundant, western Mississippi also contains naturally occurring water bodies that offer alternative forage opportunities to these species. How cormorants or egrets distribute themselves among these 2 foraging options is unknown, but it has been generally assumed each species uses aquaculture disproportionately more because of the high density of available prey. To test this assumption, we surveyed these species on aquaculture and naturally occurring water bodies using aerial surveys from October through April of 2015–2016, 2016–2017, and 2017–2018. We modeled the proportion of each species on aquaculture as a function of year, date, and weather‐related variables using quasi‐binomial generalized linear models. Egrets used aquaculture consistently more than what was proportionally available to them and use was not influenced by any of the variables we measured. Proportional use of aquaculture by cormorants was lowest during October through January but steadily increased through April, indicating a distribution shift toward aquaculture in the months immediately prior to their migration. The highest proportional use of aquaculture by cormorants occurred in 2016, a year when lethal control measures were not allowed against cormorants. Conversely, the least proportion of cormorants on aquaculture was in 2015 when cormorants could be lethally controlled under authority of an Aquaculture Depredation Order. This trend highlights the potential influence of changes in mortality risk, caused by changes in policy regarding lethal take of cormorants, on cormorant distribution between foraging options. © 2020 The Wildlife Society.

中文翻译：

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密西西比州食鱼性水产养殖和天然水体的使用

双冠cor（Phalacrocorax auritus）和大白鹭（Ardea alba）与美国西部密西西比州的水产养殖业存在着人类与野生动物冲突的悠久历史，这是由于它们对养殖cat鱼（Ictalurus）的反对spp。）。尽管水产养殖业丰富，但密西西比州西部还包含天然存在的水体，为这些物种提供了替代性的觅食机会。2或白鹭如何在这两种觅食方式中分布自己是未知的，但是由于可用猎物的密度高，一般认为每种物种更多地使用水产养殖。为了检验这一假设，我们使用航空调查从2015–2016年10月至4月，2016–2017年和2017–2018年的水产养殖和自然发生的水体对这些物种进行了调查。我们使用准二项式广义线性模型对水产养殖中每个物种的比例建模为年，日期和与天气相关的变量的函数。白鹭对水产养殖的持续使用超过了按比例分配给他们的水产养殖，并且使用不受我们所测变量的影响。October在十月至一月期间对水产养殖的按比例使用最低，但到四月稳定增长，这表明immediately迁移前几个月向水产养殖转移。cor对水产养殖的使用比例最高，发生在2016年，这一年不允许对hal进行致命的控制措施。相反，在水产养殖中proportion的比例最小，是在2015年，根据《水产养殖淘汰法令》可以致命地控制cor。这一趋势突显了死刑风险变化的潜在影响，这是由于有关致命性of攻击的政策变化引起的，关于觅食选项之间的cor分布。©2020野生动物协会。