Dunnock relatively lower success for females. In times of scarcity, female territories expand to accommodate the lack of resources, causing males to have a more difficult time monopolizing females. Hence, females gain a reproductive advantage over males in this case. The dunnock possesses variable mating systems. Females are often polyandrous, breeding with two or more males at once, which is quite rare among birds. This multiple mating system leads to the development of sperm competition amongst the male suitors. DNA fingerprinting has shown that chicks within a brood often have different fathers, depending on the success of the males at monopolising
Common blackbird dark Places about it", and it symbolised resignation in the 17th century tragic play "The Duchess of Malfi"; an alternate connotation is vigilance, the bird's clear cry warning of danger. The common blackbird is the national bird of Sweden, which has a breeding population of 1–2 million pairs, and was featured on a 30 öre Christmas postage stamp in 1970; it has also featured on a number of other stamps issued by European and Asian countries, including a 1966 4d British stamp and a 1998 Irish 30p stamp. This bird—arguably—also gives rise to the Serbian name for Kosovo, which is