The Black Monarch Symposiarchus axillaris, endemic to low montane forests in New Guinea, is socially monogamous and a territorial pair breeder. It builds a deep cup-shaped nest that is externally composed of moss. Watches at one nest with an egg confirmed that both male and female contribute equally in the later part of incubation. In the first 2 hours after hatching, both male and female contributed equally to brooding and feeding of the young, and in nest-defence. The combination of black skin and extensive long black down of the newly hatched Black Monarch appears to be unique amongst Australasian monarch flycatchers. The pattern of biparental care in the Black Monarch is compared with other Australian and New Guinean monarchs, particularly the Leaden Flycatcher Myiagra rubecula. Equal investment in provisioning of offspring by the male and the female may indicate a low benefit from extra-pair copulations.