Yan is not an opportunistic forager. She won't fly around aimlessly and eat plankton in the air with her mouth open. Instead, they will take the initiative to prey on specific prey.
Species distributed in the same field usually prey on invertebrates of different sizes. As far as a certain kind of individual is concerned, it often chooses the biggest prey it can get. The food of migratory birds in winter is usually different from that in the breeding ground.
If Ru Yan overwinters in Africa, the proportion of ants in food will increase. In addition, a species' preference for foraging in winter and breeding areas will be different. These changes are considered to be the result of competition between these migratory birds and winter residents.
Extended data
Life habit of domestic swallow: domestic swallow is good at flying. For most of the day, it flies in groups over the village and its nearby fields. It is fast and agile, sometimes flying high, soaring in the air like an eagle, sometimes flashing near the water, up and down, with no fixed flight direction, and sometimes constantly making sharp and urgent calls.
The range of activities is not large, usually within 2 square kilometers of the habitat. Daily activities take a long time. According to the observation in Changbai Mountain, activities usually start at 4 am and end at 7 pm. Especially at 7: 00-8: 00 and 17: 00- 18: 00, they are most active and often have a short rest at noon. Sometimes they also move with the golden swallows.
Baidu Encyclopedia-Yan Jia
Baidu Encyclopedia-Yan