Bird: Redhead (Aythya americana) 美洲潛鴨

The first time I saw a Redhead was in Lake Arrowhead, California in 2019. Redhead is a medium-sized pochard, diving duck specially adapted to foraging underwater. During breeding season, adult males have a copper head and neck and they are very prominent. Wetlands are their main habitat. Redheads pair up on the wintering grounds and the pair bond strengthens during spring migration. Seasonally monogamous, female Redheads use several strategies to maximize their chances of producing young: they can either brood their own clutch of eggs, “parasitize” another bird’s nest by depositing eggs into it, or combine the two approaches in a “semi-parasitic” approach, leaving eggs in another nest before laying a clutch to brood.
我第一次看到美洲潛鴨是在2019年在加州的箭頭湖(Lake Arrowhead)。美洲潛鴨是一種中型潛水鴨,特別適合在水下覓食。在繁殖季節,成年雄鴨有銅色的頭和頸,非常突出。濕地是它們的主要棲息地。美洲潛鴨在越冬地結成對,在春季遷徙期間配對的結合會加強。季節性一夫一妻制的雌性美洲潛鴨會使用多種策略來增加生育後代的機會:它們可以孵化自己的一窩蛋,或將蛋放入另一個巢“寄生”,或者將這兩種方法結合成“半寄生”的方法,在下一窩蛋孵化之前將蛋留在另一個巢中。

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Photo Date: 2019.12.06 Location: Lake Arrowhead, California

Notes 筆記

  • The Redhead is a medium-sized pochard, diving duck specially adapted to foraging underwater. The redhead goes by many names, including the red-headed duck and the red-headed pochard. Their legs are placed farther back on the body, which makes walking on land difficult, the webbing on their feet is larger than dabbling ducks and their bills are broader, to facilitate underwater foraging. In addition, pochards have a lobed hind toe.
  • During breeding season, adult males have a copper head and neck, with a black breast. Male bills are pale blue with a black tip and a thin ring separating the two colours. Non breeding males lose the copper colour and instead have brown heads. Adult females, however, have a yellow to brown head and neck. Females remain the same colour year round.
  • During breeding season, redheads are found across a wide range of North America, from as far north as Northern Canada to the Caribbean. They will migrate south to winter in warmer climates.
  • Redheads use wetlands as their main habitat. When wintering, redheads switch to large areas of water near the coast that are protected from wave action but can also be found in reservoirs, lakes, playa wetlands, freshwater river deltas, coastal marshes, estuaries and bays.
  • Redheads flock together on lakes and other bodies of water but will migrate in pairs, which are formed in December or January through elaborate courtship rituals. Unpaired redheads will migrate together in a ‘courting party’ that can be up to 25 individuals strong and hopefully find a mate within the group. The pair bonds are established yearly through a long courtship process.
  • Redheads do not defend their territory or home range and are actually very social while in their breeding ground.
  • All pochards have similar diets that include both plant and animal materials. During the breeding season, redheads will eat as much animal matter as possible, including gastropods, mollusks and insect larvae. However, once they fly south, redheads will change their diet to include mostly plant material.
  • 美洲潛鴨是一種中型潛水鴨,特別適合在水下覓食。美洲潛鴨有很多名字,包括紅頭鴨和紅頭潛鴨。它們的腿在身上更靠後些,使得它們在陸地上行走變得困難,它們腳上的蹼比鑽水鴨大,而且它們的喙更寬,以便於在水下覓食。此外,潛鴨的後趾呈淺裂狀。
  • 在繁殖季節,成年雄鴨有銅色的頭和頸,黑色胸部,淡藍色的喙,尖端是黑色,並有一個細環將兩種顏色分開。非繁殖雄鴨沒有銅色的頭,而是棕色的頭。然而成年雌鴨的頭部和頸部是黃色至棕色,整年保持相同的顏色。
  • 在繁殖季節,從北至加拿大北部到加勒比海地區,北美許多地區都有美洲潛鴨。它們會向南遷徙到溫暖的氣候過冬。
  • 美洲潛鴨以濕地為主要棲息地。過冬時會轉移到靠近海岸的大片水域,這些水域不受波浪的影響,也可以在水庫、湖泊、干鹽湖濕地、淡水河流三角洲、沿海沼澤、河口和海灣中看到它們。
  • 美洲潛鴨在湖泊和其他水域聚集在一起,但會成對遷徙,配對是在12月或1月經精心設計的求愛儀式而形成的。不成對的美洲潛鴨會在最多25隻鴨的“求偶派對”中一起遷徙,並希望在群體中找到配偶。每年配對的結合都是藉由漫長的求愛過程。
  • 美洲潛鴨不保衛自己的地盤或家園,實際上在繁殖地時常群居。
  • 所有的潛鴨都有類似的飲食,包括植物和動物。 在繁殖季節,美洲潛鴨盡可能多地吃動物,包括腹足動物、軟體動物和昆蟲幼蟲。然而一旦它們飛向南方,美洲潛鴨改變它們的飲食,主要吃植物。

References 參考資料

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