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
Acrocephalus (bird) Acrocephalus (bird) The Acrocephalus warblers are small, insectivorous passerine birds belonging to the genus "Acrocephalus". Formerly in the paraphyletic Old World warbler assemblage, they are now separated as the namesake of the marsh and tree warbler family Acrocephalidae. They are sometimes called marsh warblers or reed warblers, but this invites confusion with marsh warbler and reed warbler proper, especially in North America, where it is common to use lower case for bird species. These are rather drab brownish warblers usually associated with marshes or other wetlands. Some are streaked, others plain. Many species breeding in temperate regions are migratory. This