Pair if eurasian magpies occupy a nest visible from my balcony. It's the nesting season for them here, and I assumed they have laid eggs. I can't see the eggs directly, but one of the magpies has been regularly sitting inside the nest (at least for last two or three weeks) and they always attack other birds that come too close.
Today, they've started building a new nest on another tree. It's pretty close, the nests are about 20 meters apart. They still visit their original nest.
What does it mean? Is it a sign of nesting failure? Does it mean their original nest is no longer sufficient?