During the past week and a half it has turned quite cold, and our backyard bird feeders1 have become very busy with all types of birds feeding on the various types of seeds that Kim puts out for them. Some tiny, frail-looking2 little birds called black capped chickadees3 have also been feeding there. We have been interested in them for several years, wondering how they can even survive the often frigid temperatures4 which we can have in Iowa. Many other birds leave before the truly cold weather arrives, but the little chickadees stay, as do some of the much bigger birds5.
Yesterday I found out about their survival techniques6 when I received my copy of NATIONAL WILDLIFE, a journal7 published by the National Wildlife Federation8, of which I am a member. An article written by a biologist who has spent over twenty-five years studying these tiny birds provided the answer for me. The chickadee survival involves9 several different things. During the warmer periods the bird carefully hides10 extra food items that it can use later. It also grows a dense winter coat of feathers11 and finds specially selected cavities12 in trees where it can roost13and be protected. Most interesting of all, the bird can control its body temperature14, lowering it at night in a controlled manner15 to about 12 to 15 degrees F below its normal daytime temperature of 108 degrees F. This allows the bird to conserve16 almost 25 percent of its hourly metabolic energy loss17 when the outside temperature is freezing or below. The lower the outside temperature, the more energy the bird conserves.
We had noticed that the chickadees eat all day long at our bird feeders, and that is normal for them. I also found out that sunflower seeds18 are especially helpful for them, so I am glad that Kim already adds a lot of them to the mix of seeds she puts in the feeders.
The squirrels19 also like the sunflower seeds. They have eaten a lot of them and they are especially fat this year. We all wonder how they can jump from branch to branch because they are so fat. However, they manage to do it anyway. They are so fat that when they are on the ground they almost look more like a rabbit20 or possum21 in size. I’ve heard of an old folk belief22 that if the little animals are especially fat that means a severe winter. If that is true, our squirrels are predicting a severe winter with their bulk23. We’ll wait and see. Meanwhile, it’s fun to watch our busy bird feeders.
Notes:
1. bird feeders: structures made to be placed outdoors, and which contain food offered to birds in the area (喂鸟的饲盘、饲槽).
2. frail-looking birds: small, weak looking, or thin birds (瘦小、稚弱的鸟).
3. chickadees: a type of bird which is found in North America in the autumn of the year (山雀，常见于北美洲的秋天).
4. survive the often frigid temperatures: stay alive and carry on normal behavior despite very cold temperatures (熬过经常有的极其寒冷的天气).
5. as do some of the much bigger birds: some of the much bigger birds stay too.
6. survival techniques: ways of surviving (幸存的技能) .
7. journal: a magazine (杂志)
8. Nation Wildlife Federation: an organization which promotes the care of wild animals, and of their habitats (国家野生动物联合会).
9. involves: includes (包含，涉及)
10. hides: places items where they are not seen by other birds or animals (把……藏起来).
11. a dense winter coat of feathers: 又密又厚的过冬羽毛
12. cavities: holes or crevices (洞)
13. roost: rest from active movement; stay for periods of time, usually in a tree or elevated place (栖息).
14. control its body temperature: 控制自己的体温
15. in a controlled manner: in a way which is readily maintained or kept (可以掌控地).
16. conserve: keep or maintain a particular item or situation (保住，保留).
17. metabolic energy loss: the amount of energy that is derived from food, and which is lost to the environment (新陈代谢过程中的能量损耗).
18. sunflower seeds: the dried fruits of the sunflower plant (葵花子).
19. squirrels: 松鼠
20. rabbit: 兔子
21. possum: 负鼠
22. folk belief: a story that has been told so frequently that it is widely believed by people (民间、信念).
23. bulk: the large size, or the total weight (肥壮的身体).
