Colony sizes of weavers

  Oschadleus HD 2020 Variation in colony sizes of weavers from a citizen science project. Ostrich online

Download a pdf of the paper here (limited to 50 copies, thereafter email me for a copy)

 

A new paper describes the range of colony sizes in weavers, based on the citizen science project, PHOWN (PHOtos of Weaver Nests).  The paper provides quantitative colony size data for 80 of the existing 117 weaver species. While there are sometimes enormous colonies, generally weaver colonies are small. The average colony size for most species (66% of the 80 sampled species) was less than 10 nests.

Village Weaver colony of 150 nests

 

Six species had a mean colony size of >50 nests: Red-headed Quelea, Red-billed Quelea, Speke’s Weaver, Clarke’s Weaver, Chestnut Weaver, and Sociable Weaver (>50 nest chambers in this case). Even species that often breed in large colonies, may sometimes have small colonies or even one male with a single nest. The figure below shows that most weaver species tend to have small colony sizes on average, but there are quite a few species that do have quite high colony sizes on average.

Weaver colony sizes

 

Southern Masked Weavers colonies

The species with the most PHOWN records is the Southern Masked Weaver, with over 8000 records. Southern Masked Weavers usually have small single-male colonies, with less than 10 nests in a colony. Some colonies may attract a large number of males, and contain hundreds of nests in an area. PHOWN gives the following stats for this species:

Average colony size: 4.5 nests, s.d. = 6.1

Range: 1 – 165 nests

n=8020 PHOWN records with nest counts.

There is scope for more detailed analyses of colony sizes for this species due to the large sample size. Other weavers with large samples (over 300) in the PHOWN database are:
White-browed Sparrow-weaver, Cape Weaver, Village Weaver, Red-billed Buffalo-Weaver, Sociable Weaver, and Red-headed Weaver.

Thanks!

More than 23000 PHOWN records included nest counts – thanks to all the citizen scientists that contributed records to this Virtual Museum!

To take part, register and upload records at the UCT Virtual Museum web (read the “How to” pdf for help)

Dieter
Dieter is a qualified Bird Ringer and trainer, registered bird guide, and Weaver expert. Dieter is able to act as a bird guide for day trips in Cape Town, and is able to customise birds tours in South Africa and beyond.