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 miner Common miner The common miner ("Geositta cunicularia") is a passerine bird of South America, belonging to the ovenbird family. It is a ground-dwelling bird which feeds on insects and seeds. It has about 9 different subspecies, some of which may be better treated as separate species. It is 14 to 16 cm long with a fairly long, slightly downcurved bill. The plumage varies geographically but is basically brown above and pale below with a streaked breast, pale stripe over the eye, dark edge to the ear-coverts and pale rufous bar across the wing. The tail is dark with a buff