Until I saw two pairs of white color geese together, one pair was bigger than the other. Then I learned that the bigger pair was Snow geese and the smaller pair was Ross’s geese. Because they are almost the same in appearance, you can tell them apart by their size when they are side by side. By zooming in on the photo and looking at their bills, then you can confirm who is who. If you would like to understand the characteristics of the Ross’s goose, you can read the previous post.
直到我看到兩對白色的雁在一起，一對比較大，另一對比較小，我才知道大的一對是雪雁，另一對是細嘴雁。因於它們外型幾乎一樣，放在一起才看得出大小，再仔細放大照片看它們的喙，才能分得清楚誰是誰。想要了解細嘴雁的特性，可讀上一篇文章。
Image Gallery-Click to enlarge 圖片庫-點擊放大
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Notes 筆記
- The snow goose’s name derives from the typically white plumage. The snow goose has two color plumage morphs, white (snow) or gray/blue (blue). White-morph birds are white except for black wing tips, but blue-morph geese have bluish-grey plumage replacing the white except on the head, neck and tail tip. Both snow and blue phases have rose-red feet and legs, and pink bills with black tomia (“cutting edges”), giving them a black “grin patch”.
- Snow Geese are vegetarians with voracious appetites for grasses, sedges, rushes, forbs, horsetails, shrubs, and willows.
- Snow geese breed north of the timberline in Greenland, Canada, Alaska, and the northeastern tip of Siberia, and spend winters in warm parts of North America from southwestern British Columbia through parts of the United States to Mexico.
- Females are strongly philopatric, meaning they will return to the place they hatched to breed. Snow geese often nest in colonies. The female selects a nest site and builds the nest on an area of high ground. The female incubates for 22 to 25 days, and the young leave the nest within a few hours of hatching. The young feed themselves, but are protected by both parents.
- Snow geese breed from late May to mid-August, but they leave their nesting areas and spend more than half the year on their migration to-and-from warmer wintering areas. They migrate in large flocks.
- Major nest predators include Arctic foxes and skuas.
- 雪雁的名字來源於典型的白色羽毛。雪雁有兩種顏色的羽毛變體，白色(雪)或灰色/藍色(藍)。白者除黑色翼尖外，身體為白色。而藍者除了頭，頸和尾巴尖外，藍灰色的羽毛代替了白色。兩種雁的腳和腿均為玫瑰紅色，粉紅色的喙上有黑色的嘴緣（“刃口”），像個黑色的“齜牙咧嘴斑塊”。
- 雪雁是素食者，喜愛草，莎草，燈芯草，牧草，馬尾草，灌木和柳樹。
- 雪雁在格陵蘭，加拿大，阿拉斯加和西伯利亞的東北端林線的北部繁殖，並在北美溫暖地區從不列顛哥倫比亞省西南部到美國部分地區到墨西哥度過冬季。
- 雌性有很高的思鄉性，就是說它們會返回孵化繁殖的地方。雪雁經常成群築巢。雌鳥選擇築巢地點，並在高地上築巢。雌性孵化22到25天，而幼雁則在孵化幾小時之內離開巢穴。幼雁自己養活自己，但受到雌雄親鳥的保護。
- 雪雁從5月下旬到8月中旬繁殖，但花了超過半年的時間離開巢穴往較溫暖的越冬地區遷移。它們是成群地遷徙。
- 主要的巢穴掠食者包括北極狐和賊鷗。
References 參考資料
- Wikipedia: Snow goose
- All about birds: Snow Goose
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