讨论关于birds anting这一习性的三种解释。
Refute the three explanations mentioned in reading passage.
1. It is just a coincidence between the time of feather change and bird anting.
2. Anting cannot reduce the growth of parasites on some birds.
3. Birds will have other things to rub themselves, but they do not tend to eat those things.
Demonstrate three theories to explain why birds have the habit.
1. Birds use anting to irrigate skin during feather change in summer.
2. The acid released during anting by ants can help resist parasites growing on birds.
3. Anting is a way for birds to feed on those ants.