Human houses have changed from adobe houses and brick houses into concrete and reinforced concrete buildings. With the change of building structure, eaves began to disappear and were replaced by neat buildings. Swallows can't find a place to nest, so we seldom see swallows in ordinary buildings, but in some rural areas with eaves, swallows' nests are quite common.
Secondly, because people seldom sprayed pesticides on crops in the past, they were all natural. Nowadays, in order to resist the invasion of insects, a large number of insects are sprayed, resulting in a large number of reduction or variation. Swallows eating these poisonous or mutated insects may die or reduce their reproductive ability, resulting in a decrease in population.
Air changes and pollution have also led to a decrease in the number of swallows and other birds. With the development of science and technology, it brings convenience to mankind, but it also brings bad influence to our environment. The reduction of green plant area destroys the ecological environment, and the garbage formed by white pollution may make animals eat by mistake, which affects the migration habit of swallows from south to north caused by global warming. ...
More importantly, this is also the most disgusting point. For human reasons, some people are not satisfied with three meals a day to find some game. Bird's nest is made into expensive nutrition, swallows are killed and made into dishes, and many people eat wild animals but shout the slogan of protecting animals.
When we were young, we all said that swallows are birds that bring blessings, but maybe in a few decades, our children will not understand what swallows look like in colorful clothes. We can only look at specimens and pictures. We can protect the environment without changing it. We can cast artificial nests without changing the building. We can give the swallows a chance to survive without forcing them. So please use your actions to save the birds that can bring us blessings from now on.