Morphological and behavioural evidence of relationships of the Cuckoo Finch Anomalospiza imberbis

Viduids are African finches that are obligate brood parasites, using other species to incubate their eggs and care for their young (Payne 1996, 1997a, b, 1998). Of 20 viduid species, 19 are indigobirds and whydahs in the genus Vidua, and one is the Cuckoo Finch Anomalospiza imberbis. Recent analysis of mtDNA sequence data supports the idea that Anomalospiza and Vidua are each others’ closest relatives and their common ancestor was a brood parasite (Sorenson & Payne 2001). The molecular genetic distance between the two genera indicates that brood parasitism originated in these finches c. 17-20 million years ago. Moreover, the parasitic finches (Viduidae) are most closely related to the grassfinches (Estrildidae) in a sister relationship, and are not closely related to the weaverfinches (Ploceidae) (Sorenson & Payne 2001). Anomalospiza are yellowish in plumage (adult males in breeding season; they are more dull in the non-breeding season) or sparrowy-brown (females and juveniles), stocky, thick-billed birds. They superficially resemble in plumage a number of other finches with which they flock in the breeding season. They are brood parasites on Prinia and Cisticola warblers of open grasslands (Vernon 1964). The systematic relationship of Anomalospiza has a long and contentious history. Although no comprehensive phylogenetic analysis included Anomalospiza until Sorenson & Payne (1998, 2001), certain morphological and behavioural features had been used to support its affinity with various families. Here we describe morphological and behavioural features which support the molecular evidence that Anomalospiza is a viduid finch.