Evolution and systematics

The family Motacillidae is well defined and homogeneous but its relationships to other oscine passerine groups (singing birds such as larks, finches, and crows), as indicated by traditionally accepted morphological characters, are obscure. The family was once placed next to the larks (Alaudidae) but later widely accepted classifications placed it between the Hirun-dinidae (swallows and martins) and the Campephagidae (cuckoo-shrikes). However, egg-white protein evidence suggests ties with Old World warblers and flycatchers (Musci-capidae). The greatly reduced outermost primary feathers suggests affinities with nine-primaried oscines and this is supported by DNA hybridization evidence; which led researchers to treat the group as a subfamily (Motacillidae) within the family Passeridae, alongside the subfamilies Passerinae (sparrows), Prunellinae (accentors), Ploceinae (weavers), and Es-trildinae (waxbills).

It has been proposed that two African endemic species, Sharpe's longclaw (Macronyx sharpei) and the yellow-breasted pipit (Anthus chloris) should be associated in the genus Hemi-macronyx (or even that both should be placed in Anthus) on the basis of shared characteristics suggesting that they form a link between the pipits and the longclaws. However, this is not justified in terms of the many typical longclaw characteristics shown by Sharpe's longclaw. In structural characters and behavior, the yellow-breasted pipit resembles typical pipits more than it resembles Sharpe's longclaw.

The first fossil material for the family dates back to the Upper Oligocene, about 30 million years ago. During the

Miocene epoch (26-7 million years ago), when drying conditions reduced forests and encouraged the spread of grasslands, this and other bird families radiated extensively into these more open habitats.

0 0

Post a comment