Weaver news

Weaver Wednesday [2]: White-browed Sparrow-Weaver

2012-06-27 (231)

There are four species of sparrow weavers. The sexes are similar and they are brownish above and white below with a prominent eye-stripe. They are found in dry savanna country and build nests of grass stems, usually in thorn trees. They are monogamous, co-operative breeders. The nests have two entrances, but one is closed in breeding nests.

The White-browed Sparrow-Weaver Plocepasser mahali is the most widespread, occurring in southern and eastern Africa. It's nest sometimes has a longer entrance, as shown right (VM 3).

The White-browed Sparrow-Weaver has four subspecies - the nominate in southern Africa [red on the map]; ansorgei in northern Namibia to Angola [green]; pectoralis from Zambia to central Tanzania [blue] showing dark markings on the breast (see photo here); and melanorhynchus from northern Tanzania to Sudan [pink].

The White-browed Sparrow-Weaver appears to have increased its range and abundance in many areas (read more here). For example, in the Eastern Cape it was first seen on Rookwood farm in the1980s, and since 2000 has several colonies (see sparrow-weaver colonies on Rookwood here). This species has probably increased number of nests at Barberspan (see here). The species seems to be increasing in Kenya, e.g. it was described as a new-comer to Ngulia in the past 2 years (VM 1977) and is increasing in Nairobi.

The White-browed Sparrow-Weaver is well represented in PHOWN, ranking fifth in terms of number of records submitted. There are records for all four subspecies. The average colony size is 16 nests. In some weaver species the colony size has been shown to be correlated with breeding output (more nests = more chicks produced). In the White-browed Sparrow-Weaver this is unlikely to be correct as a colony consists of a dominant pair, with cooperative helpers, that raise one brood at a time. However, it will be valuable to continue recording colony size in this species as there are many unanswered questions - e.g. do colonies grow bigger over time? (or only in less windy areas?, etc). In general, more PHOWN records are needed for this species, as is the case for all Virtual Museum taxa. For sparrow-weavers in particular, annual repeats are needed to show long-term stability of colonies and long-term colony size changes.

See all PHOWN records for the White-browed Sparrow-Weaver here.


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