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. The males sing throughout much of the construction and even more so when a female approaches his nest. Following copulation, the male and female continue to build the nest. Nests may be in any type of hole, common locations include inside hollowed trees, buildings, tree stumps and man-made nest-boxes. S. v. zetlandicus typically breeds in crevices and holes in cliffs, a habitat only rarely used by the nominate form. Nests are typically made out of straw, dry grass and twigs with an inner lining made up of feathers, wool and soft leaves. Construction usually takes four or five days and may continue through incubation. Common starlings are both monogamous and polygamous; although broods are generally brought up by one male and one female, occasionally the pair may have an extra helper. Pairs may be part of a colony, in which case several other nests may occupy the same or nearby trees. Males may mate with a second female while the first is still on the nest. The reproductive success of the bird is poorer in the second nest than it is in the primary nest and is better when the male remains monogamous. Breeding Breeding takes place during the spring and summer. Following copulation, the female lays eggs on a daily basis over a period of several days. If an egg is lost during this time, she will lay another to replace it. There are normally four or five eggs that are ovoid in shape and pale blue or occasionally white, and they commonly have a glossy appearance. The colour of the eggs seems to have evolved through the relatively good visibility of blue at low light levels. The egg size is in length and in maximum diameter. Incubation lasts thirteen days, although the last egg laid may take 24 hours longer than the first to hatch. Both parents share the responsibility of brooding the eggs, but the female spends more time incubating them than does the male, and is the only parent to do so at night