Effects of Gull Predation and Predator Control on Tern Nesting Success at Eastern Egg Rock, Maine
Effects of Gull Predation and Predator Control on Tern Nesting Success at Eastern Egg Rock, Maine
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海鸥捕食和捕食者控制对缅因州东蛋岩燕鸥筑巢成功的影响
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发表时间：
2007
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通讯作者：
Stephen W. Kress
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作者：
Christina E. Donehower;David M. Bird;C. S. Hall;Stephen W. Kress
摘要海鸥捕食是许多海鸟卵和雏鸟死亡的重要原因。从2003年到2005年，在缅因州的东蛋岩研究了海鸥捕食和捕食者控制计划对燕鸥筑巢成功的影响。2003年，海鸥的捕食行为不受控制，在2004年和2005年，人们试图射杀鲱鱼（Larus argentatus）、大黑背鸥（L. marinus）和笑鸥（L. atricilla），这些海鸥捕食普通鸥（Sterna hirundo）、北极鸥（S. paradisaea）和玫瑰鸥（S. dougallii）的燕鸥成鸟、蛋和雏鸟。为了评估清除海鸥的有效性，每天在观察塔上进行观察，每年测量燕鸥的孵化和羽化成功率。尽管在2004-2005年期间采取了射击措施，但许多已知的食肉动物仍无法被清除。大黑背鸥的捕食行为与年份、潮汐状态和能见度有关，而银鸥的捕食行为仅取决于燕鸥繁殖周期的阶段。利用监测到的鸟巢中鸟蛋和雏鸟的消失作为海鸥捕食压力的代表，在研究期间，估计有23%的普通燕鸥、32%的北极燕鸥和6%的玫瑰燕鸥鸟巢遭到了海鸥的破坏。捕食风险取决于种群内巢穴的位置，而不是年份，有些地区比其他地区更容易受到海鸥的攻击。我们讨论了从缺乏筑巢的鲱鱼和大黑背鸥的燕鸥群中清除掠食性海鸥的困难，并提出了人类存在和相关研究活动对减少该地点海鸥捕食的重要性。
Abstract Gull predation is an important source of egg and chick mortality for many seabirds. From 2003-2005, the effects of gull predation and a predator control program on tern nesting success were studied at Eastern Egg Rock, Maine. In 2003, gull predation was uncontrolled, and in 2004 and 2005, attempts were made to shoot Herring (Larus argentatus), Great Black-backed (L. marinus), and Laughing (L. atricilla) gulls that preyed on Common (Sterna hirundo), Arctic (S. paradisaea), and Roseate (S. dougallii) tern adults, eggs, and chicks. To evaluate the effectiveness of gull removal, daily watches were performed from an observation tower and tern hatching and fledging success were measured annually. Despite shooting efforts in 2004-2005, many known predators could not be removed. Great Black-backed Gull predation was a function of year, tidal state, and visibility, while Herring Gull predation depended only on the stage of the tern breeding cycle. Using disappearance of eggs and chicks from monitored nests as a proxy for gull predation pressure, an estimated 23% of Common, 32% of Arctic, and 6% of Roseate tern nests were depredated by gulls during the study period. Predation risk depended on nest position within the colony, but not year, with some areas consistently more vulnerable to gulls than others. We discuss the difficulty of removing predatory gulls from a tern colony lacking nesting Herring and Great Black-backed gulls and suggest the importance of human presence and associated research activities for reducing gull predation at this site.