Demography and Populations

Many nests fail due to predation, especially at the egg stage. The maximum elapsed time (longevity) in ringing studies is at least five years and one month. Two species of chewing lice species have been recorded on adults, one of which seems to be host-specific. One nest mite species has been recorded. Adults have been reported to be infected with several species of blood parasites. Causes of mortality include a very cold spell, possibly combined with starvation, and nests containing young birds starved for an unknown reason.

In the Kgalagadi Transfrontier Park, the population is estimated at more than 500,000 adults. In its major stronghold in the southern and central Kalahari, it occurred at an average density of 9 birds/ha . Densities are lower in other areas, and temporarily higher after exceptional early rainfall. The population seems to be stable but may possibly be increasing in some areas, and it has expanded its range on some edges of its range.

Breeding Success

In the Northern Cape Province, South Africa, 9 of 30 nests failed to hatch any eggs (through predation), with daily nest predation rates estimated at 2.15 ± 0.71% (103 Lloyd, P. (2004). Variation in nest predation among arid-zone birds. Ostrich 75(4):228–235. Close ). In the Polokwane Game Reserve, 27 eggs were laid in 9 nests under observation, and 4 nestlings fledged, giving a crude breeding success estimate of 14%. Most nests (n = 12) were lost during the incubation stage (74 Engelbrecht, D. (2023). Field notes: Scaly-feathered Weaver. Lark 45:95–99. Close ).

See Behavior: Predation for information on nest predators.

The maximum elapsed time (longevity) in ringing studies is at least five years and one month (104 Oschadleus, H. D. (2016). Longevity records of southern African weavers. Biodiversity Observations 7.59:1–18. Close ).

Two chewing lice species have been recorded on adults: Brueelia sp.n. (105 Takano, O. M., G. Voelker, D. R. Gustafsson, and J. E. Light. (2018). Molecular phylogeny and novel host associations of avian chewing lice (Insecta: Phthiraptera) from South Africa. Systematic Entomology 44(2):289-304. Close ) and the seemingly host-specific Myrsidea eisentrauti Klockenhoff, 1982 - 8 of 13 birds were parasitized by the latter in one study (106 Halajian, A., O. Sychra, W. Luus-Powell, D. Engelbrecht, and I. Papousek (2014). An annotated checklist of amblyceran chewing lice (Phthiraptera: Amblycera) from wild passerine birds (Passeriformes) in South Africa. African Entomology 22(4):762-778. Close ).

One nest mite has been recorded, but the species has not been fully determined, Pellonyssus reedi/malurus (107 Till, W. M. (1964). A revision of the genus Pellonyssus Clark and Yunker (Acari: Mesostigmata). Journal of the Linnean Society (Zoology) 45:85-102. Close ).

Adults have been reported to be infected with the blood parasites Plasmodium (Novyella) nucleophilum (2 of 12 birds) (108 Manwell, R. D., and G. S. Rossi. (1975). Blood Protozoa of imported birds. Journal of Eukaryotic Microbiology 22:124-127. Close ), Haemoproteus sp. (1 of 15 birds) (109 Earlé, R. A., G. F. Bennett, H. du Toit, D. H. de Swardt, and J. J. Herholdt (1991). Regional and seasonal distribution of avian blood parasites from northern South Africa. South African Journal of Wildlife Research 21:47-53. Close ), Haemoproteus passeris (110 Bennett, G. F. and M. A. Peirce. (1991). The haemoproteids of the weaver finches (Passeriformes). Journal of Natural History 25:7-22. Close ), and Hepatozoon passeris (2 of ~50 birds) (111 Bennett, G. F., R. A. Earlé, and D. Squires-Parsons (1995). Additional new species of Haemoproteus, Herpatozoon and Leucytozoon from South African birds. South African Journal of Wildlife Research 25:1-7. Close ).

In Zimbabwe, four adult males and four females died after a very cold spell in early summer, possibly combined with starvation (112 Steyn, P., and R. K. Brooke (1971). Cold-induced mortality of birds in Rhodesia during November 1968. Ostrich 8:271-282. Close ). One or two nests containing young birds were either deserted, or the parents were killed, leaving the nestlings to starve (4 Mouritz, L. B. (1915). Notes on the ornithology of the Matopo District, Southern Rhodesia. Part II. Ibis 10(3):534-571. Close ).

In its major stronghold in the southern and central Kalahari, the Scaly Weaver occurred at an average density of 9 birds/ha as recorded in transect counts in the Kutse Game Reserve (1 Craig, A. J. F. K. (2004). Ploceus olivaceiceps (Reichenow). Olive-headed Weaver. In The Birds of Africa. Vol. VII. (C. F. Fry and S. Keith, Editors), Christopher Helm, London, United Kingdom. pp. 189–191. Close ), while an average of 2.5 birds/ha was found in 19 transects in seven bushveld habitats in northern and eastern Botswana (46 Herremans, M. (1997). Scalyfeathered Finch. In Harrison, J. A. et al. (Editors). The Atlas of Southern African Birds. Volume 2:546-547. BirdLife South Africa, Johannesburg, South Africa. Close ). After exceptional early rainfall in October 2018 in the Gondwana Namib Desert Park, it was recorded at a higher-than-normal density of 13.4 birds/ha in late December 2018, but this had dropped to 1.1 birds/ha by early March 2019 (113 Brown, C. (2020). Density estimates of Lark-like Buntings and other seed-eating birds in the central Namib after exceptional early rainfall. Lanioturdus 53(3):12-21. Close ). In Limpopo Province, the density in mixed Vachellia woodland was estimated at 1 pair/20 ha; but the species was absent from broad-leaved wild syringa (Burkea africana) woodland in the same area (53 Tarboton, W. R. (1980). Avian populations in Transvaal savanna. In: Johnson, D. N. (Editor). Proceedings of the 4th Pan-African Ornithological Congress, pp. 113-124. Southern African Ornithological Society, Johannesburg, South Africa. Close ).

The Scaly Weaver is not a colonial nester in the formal sense, but nests are sometimes clustered in a relatively small area (64 Skead, C. J. (1995). Life-history notes on East Cape bird species (1940-1990). Volume 1. Algoa Regional Services Council, Port Elizabeth, South Africa. Close ). The mean size of nesting aggregations was given as 1.8 nests ± 1.2 SD (range 1–5, n = 20 (114 Oschadleus, H. D. (2020). Variation in colony sizes of weavers from a citizen science project. Ostrich 91(2):174-178. Close ). Further information needed.

Numbers

Locally common. In Kgalagadi Transfrontier Park, the population is estimated at more than 500,000 adults (115 Kemp, A. C., J. J. Herholdt, I. Whyte, and J. A. Harrison (2001). Birds of the two largest national parks in South Africa: a method to generate estimates of population size for all species and assess their conservation ecology. South African Journal of Science 97:393-403. Close ). The mean reporting rate within its southern African range is 26.0% (46 Herremans, M. (1997). Scalyfeathered Finch. In Harrison, J. A. et al. (Editors). The Atlas of Southern African Birds. Volume 2:546-547. BirdLife South Africa, Johannesburg, South Africa. Close ).

Trends

In the absence of any substantial threats or evidence of a decline in numbers, the population seems to be stable (116 BirdLife International (2023). Species factsheet: Sporopipes squamifrons. Downloaded on 16/02/2023. Close ). The Scaly Weaver may possibly be increasing in numbers, as it responds positively to bush encroachment and clearing of land for agriculture, and it has expanded its range into the Lowveld of South Africa and Zimbabwe, and also into Zambia since 1994 (see Distribution).

Information needed.