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 sandpiper but is a vulnerable species in some states of Australia. Common sandpiper The common sandpiper ("Actitis hypoleucos") is a small Palearctic wader. This bird and its American sister species, the spotted sandpiper ("A. macularia"), make up the genus "Actitis". They are parapatric and replace each other geographically; stray birds of either species may settle down with breeders of the other and hybridize. Hybridization has also been reported between the common sandpiper and the green sandpiper, a basal species of the closely related shank genus "Tringa". The common sandpiper was one of the many bird species originally described by Linnaeus in