Ecologist: Before finding a mate, male starlings decorate their nests with fragments of aromatic plants rich in compounds known to kill parasitic insects  Since these parasites are potentially harmful to nestlings, some researchers have hypothesized that the function of these decorations is nestling protection
However, males cease to incorporate such greenery once egg laying starts, which suggests instead that the function of the decorations is to attract females
Male starlings tend to decorate their nests with a greater number of aromatic plants when a caged female is positioned adjacent to the nest.