1. If the swallow cries with its mouth wide open, it may mean that it is hungry. This is usually because they are looking for food or trying to attract females to breed.
2. If the swallow's mouth is half-open, it may indicate that it is thirsty, or because the sun is too hot.
The above information is for reference only. In addition, due to individual differences and different severity of illness, it cannot be used as a final judgment, and it is for your reference only. Please pay attention to your physical condition at any time. If you feel any discomfort, I suggest you seek professional help in time, consult a doctor online or go to an offline medical institution for treatment.