 Unpaired males find a suitable cavity and begin to build nests in order to attract single females , often decorating the nest with ornaments such as flowers and fresh green material , which the female later disassembles upon accepting him as a mate . The amount of green material is not important , as long as some is present , but the presence of herbs in the decorative material appears to be significant in attracting a mate . The scent of plants such as yarrow acts as an olfactory attractant to females . 
