The nominate sub-species, M. p. pectoralis occurs in the southern reaches of the species distribution range in South Africa.

[2][5] The birds are small, measuring around 15 cm in length with males weighing 10-12 g and females weighing 9-11 g.[3] Although the sexes are similar in appearance[11] the rufous-eared warblers are one of the few species of the family Cisticolidae that display sexual dimorphism, with female birds having paler ear-patches and a narrower breast-band than the males.

[1] It is an arid-zone bird, occurring in arid and semi-arid areas with scrubby bushes and open grassland interspersed with bushy vegetation on plains and slopes.

[13] The rufous-eared warbler tends to occur in pairs of small family groups, particularly after the breeding season, and is seldom found on its own.

[10] The rufous-eared warbler is predominantly insectivorous, feeding on shield bugs, plant hoppers, beetles, termites, ants, moths and spiders.

[15] Stomach content analyses have found evidence of feeding on termites, weevils, caterpillars, beetles, plant hoppers, coccids, bugs, ants, grasshoppers, species of Araneae and Acari as well as the vegetation, fruit and seeds of certain Solanacea, Asparagaceae and Amaranthaceae species.

[16] The rufous-eared warbler spends a large portion of time on the ground,[3] and will run between patches of cover.

[3] Breeding tends to occur in late summer (January - March) in South Africa, but also in July and October in Botswana, and is generally opportunistic, following periods of rainfall.

[2][15] During the breeding season, male birds are solitary and territorial, and will perch on the top of bushes and call to attract females.

[2] The nest is a messy oval structure constructed from grass stems, leaves and/or strips of bark, and lined with soft vegetation before egg-laying.

[2] The rufous-eared warbler tends to favour non-thorny shrubs for nest-building,[17] and nests are built 0.2-1.2 m off the ground,[11] often facing east, southeast and south, which is associated with avoiding direct sunlight during the hottest hours of the day.

[2] The eggs and nestlings suffer a high rate of predation, particularly from snakes and armoured bush crickets.