LANIOTURDUS Volume 47 No 2 June 2014

Journal of the Namibia Club www.namibiabirdclub.org

Roadside colony densities of weavers in southern Angola H. Dieter Oschadleus, Michael S.L. Mills and Ara Monadjem [email protected]

Introduction Methods Weavers have adapted to a variety of Colonies were counted between the nesting sites, and are often found in road to about 200 m on both sides of high densities along roadsides the road, although large sections of (Macdonald 1990, Tarboton 2001, the route were well wooded reducing Oschadleus et al. 2003, Oschadleus visibility of colonies away from the & Franke 2006). On 21 June 2008 we road. The survey started in Cahama surveyed the main road from Cahama along the main road from Lubango to to Santa Clara in southern Angola for the Namibian border at Santa Clara. roadside colony densities of three The survey distance was 230 km weaver : Southern Masked- (Figure 1). Nests of the Red-billed Weaver velatus, White- Buffalo- Weaver, Southern Masked- browed Sparrow-Weaver Plocepasser Weaver and White-browed Sparrow- mahali and Red-billed Buffalo-Weaver Weaver were looked for, and each tree niger. This survey was with nests was considered to be one undertaken on the return trip of colony. Red-billed Buffalo-Weaver cataloging the Lubango Bird Skin nests were easily identified as Collection (Mills et al. 2010). conspicuous stick nests in trees, mostly baobabs. Chestnut-backed

Figure 1: Map of southern Angola, showing the route surveyed for weaver colonies in red, starting from Cahama (marked A on the map), crossing the Cunene River (blue arrow on the map) and ending at Santa Clara.

Lanioturdus 47(2) Page 17 June 2014 Sparrow-Weavers Plocepasser xanthops nests are slightly untidy rufoscapulatus do not occur in and not conspicuous from a distance, extreme southern Angola (since the Lesser Masked- Weaver P. habitat is unsuitable for this species) intermedius nests are untidy and with and thus typical sparrow-weaver a short tunnel, P. nests were assumed to belong to the rubiginosus nests are also untidy and White-browed Sparrow-Weaver. colonies are densely packed with Typical Ploceus nests were assumed nests. One nest of the Scaly-feathered to belong to Southern Masked- Finch squamifrons was Weavers; colonies generally consisted seen; others may have been of 1-15 nests that were tidy, overlooked. The speed travelled was compactly woven and about 2-3 m 50-90 km/h depending on the above the ground or over ponds of condition of the road. The colony water. Other Ploceus species counts are presented per 10 km road occurring in extreme southern Angola stretches, with counts from both were eliminated as follows: sides of the road combined. P. ocularius nests have a tunnel, Golden Weaver P.

Figure 2: Roadside colony densities of weavers in southern Angola. The number of nests per km for successive 10 km stretches of road, starting from Cahama and ending at Santa Clara. SMW = , WbSW = White-browed Sparrow-weaver, RbBW = Red-billed Buffalo Weaver, SfF = Scaly-feathered Finch Results of road 120 km from the border, Red-billed Buffalo-Weaver colonies although nests become common in were numerous in the baobab forest northern Namibia again (pers. obs.). 40 km either side of where the White-browed Sparrow-Weaver and Cunene River crossed the main road. Southern Masked-Weaver colonies No nests were seen along the stretch were regularly seen from the Cunene

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River to the border, with higher 180 colonies/100km (Macdonald densities at 50-60 km and 20 km 1990). from the border. Overall colony densities for the surveyed road were Southern Masked-Weaver highest for the Southern Masked- Colony densities appear to be similar Weaver at 23.5 colonies/100 km, in Angola (23.5 colonies/100 km) and followed by White-browed Sparrow- in southern Namibia: 22 Weaver at 19.6 colonies/100 km, and colonies/100km (Macdonald 1990). then Red-billed Buffalo-Weaver at 11.7 colonies/100 km. Overall White-browed Sparrow- Weaver and Southern Masked- Discussion Weaver colony densities increased The results are compared to roadside towards the south in southern counts in Namibia, to show the Angola, while Red-billed Buffalo- variation of density in different Weaver colonies were restricted regions. The visibility of nests may, largely to the baobab forest and none however, be higher in Namibia since were seen between the Cunene River density detection depends in part to and Santa Clara. Use of artificial nest density of the bush (this may vary sites by any weaver species was not seasonally), driving speed and observed in southern Angola while in number of observers. Namibia power-lines and telephone poles are often used as nest sites by Red-billed Buffalo-Weaver Red-billed Buffalo-Weavers (Brown & 1-5 males build several chambers in Lawson 1989, Oschadleus & Franke one nest mass; there can be up to 10 2006). nest masses in one tree (Tarboton 2001), so one nest mass represents a A quick internet search showed a small group of . Colony densities map with a climate change around appear to be lower in Angola (11.7 the Cunene River. The Köppen colonies/100 km) than in Namibia: climate classification 110 nests/100km over 1447 km of (http://en.wikipedia.org/wiki/K%C3 transmission towers (Brown and %B6ppen_climate_classification) Lawson 1989) and 52 shows a “Temperate highland tropical colonies/100km in central Namibia climate with dry winters” north, and (Oschadleus & Franke 2006). “Semi-arid” south of the river. This difference in climate could explain White-browed Sparrow-Weaver the increase in White-browed There are 10-12 nests per colony in Sparrow-Weaver nests. The Southern one tree or few adjacent trees; but Masked-Weaver is found in a wide only one active breeding nest in a variety of vegetation and climate colony (Tarboton 2001). Colony regimes, so it is not apparent why it densities appear to be lower in Angola shows an increase southwards. (19.6 colonies/100 km) than in Interestingly, these two weavers show central Namibia: 121 and 87 a similar roadside density, so tree colonies/100km along two road species and tree density may play a stretches in central Namibia role. (Oschadleus & Franke 2006), but higher than in southern Namibia: 11 Acknowledgements colonies/100km overall, although one The trip to Angola was sponsored by 10km section had a high density of Ursula Franke, the African Bird Club Conservation Fund, Tony Dowd and

Lanioturdus 47(2) Page 19 June 2014 Robert Angiers, with further help Mills MSL, Franke U, Joseph G, acknowledged in Mills et al. (2010). Miato F, Milton S, Monadjem A, Oschadleus D, Dean WRJ. 2010. References Cataloguing the Lubango Bird Skin Collection: towards an atlas of Brown CJ, Lawson JL. 1989. Birds Angolan bird distributions. Bulletin of and electricity transmission lines in the African Bird Club 17:43-53. South West Africa/Namibia. Madoqua 16: 59-67. Oschadleus HD, Franke U. 2006. Roadside colony densities of three Macdonald IAW. 1990. Range weaver species near Windhoek, expansion of the Masked Weaver Namibia. Lanioturdus 39(1):9-14. Ploceus velatus in the Karoo facilitated by the spread of alien Tarboton W. 2001. A guide to the mesquite trees. Ostrich 61: 85-86. nests & eggs of southern African birds. Struik, Cape Town.

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