Perching Birds: Passeroidea

This group comprises major radiations of Old World granivorous and insectivorous birds, including weavers and estrildine finches, ground-living wagtails, pipits, accentors, nectar-feeding sunbirds, and flowerpeckers, and so-called “nine-primaried oscines” diagnosed by a strongly reduced tenth primary. Seed-eating passerines (sparrows, buntings, weavers, waxbills, siskins, finches, grosbeaks) are assigned to at least five different families. The commonly used English names of seed-eating birds, such as finch or sparrow, do not translate to the formal classification but reflect traditional, conflicting uses.

Weavers, which are diverse in their ecology and behavior, craft elaborate, globular grass nests with stitches that range from simple knots to slip knots and overhand knots. Different species use different knots. Their diverse social systems, which include complex social colonies, harems and promiscuity, and isolated monogamous pairs, parallel the social systems of North American blackbirds with similar ecological correlations. Certain weavers are major agricultural pests in Africa. Estrildine finches include some of the most popular small cage birds, such as the Zebra Finch, which breeds prolifically in rapid response to unpredictable rains in its native Australia.

Featured in the avifaunas of the New World is a radiation of the so-called “nine-primaried oscines,” a diverse, colorful species that includes the wood warblers and tanagers as well as the cardinal-grosbeaks, buntings, and blackbirds. Many of these species migrate from the tropics to the United States and Canada to nest in June and July. Population declines of neotropical migrants are now a major concern.