The white plastic bags fluttering in the treetops of the Italian Alps intrigued Fabrizio Sergio. The Italian ecologist knew the trash hung from the nests of a certain bird, the black kite.

Plastic waste has let common coots reuse nests year after year. Scientists have now used the trash layers to date how old nests are.

After first checking each one for hibernating smooth newts, they placed the nests in plastic bags and hauled them off ... “There may be way more data in a bird nest than you may realize ...