One of more sad events in natural environment is to be present at as some species go gradually falling, until becoming difficult to see or even disappear.
Often these processes seem to us more related to distant countries or rare birds.
This far from the reality.
To ours around a so common and familiar species as the Barn Swallow is disappearing quickly
The repair of the old houses in the villages makes to the Swallows finding difficult to breeding places.
The changes and uses in the agricultural systems cause that the means become more unhealthy for the insectivorous species.
graph with the decrease in nine years, by SEO/BirdLife
Barn Swallow in Burgos, by Yearbook of the birds of Burgos, pdf file.
Barn Swallow in Spain, by SEO/BirdLife , pdf file.