Amazing footage shows two birds building a nest from scratch in just 15 days. Marta, 34, who wishes to keep her surname private, first spotted two western house martins setting up shop on the wall outside her office window on May 14. Marta documented the building process as the birds used dirt and their own saliva to construct the home. Marta, a business owner from Bieszczady Mountains in Poland, said: “They come to the area for food as the local insects are perfect for them. “They fly in packs so there are plenty of other nests nearby. “There’s also a small river which they drink from so they…