<
https://theconversation.com/avian-architects-weaver-birds-in-africa-have-unique-building-styles-240950>
"From afar, the acacia trees look like they have been decorated with grass
pom-poms. The birds have been busy, building shelters of straw and grass. Up
close the real shape of the “pom-poms” becomes clear: grass tubes in the form
of an upside down “U”, with an opening at each end.
These structures are the work of white-browed sparrow weavers (
Plocepasser
mahali).
White-browed sparrow weavers are cooperative breeders. Within a
multi-generational family group, only one dominant pair will reproduce; all
other birds, which are mostly kin (related), will help with the rearing of
chicks. These birds do everything together: forage, defend their territory,
feed new chicks – and build each of the many roosts that decorate the acacia
trees they live in. The birds are found throughout central and north-central
southern Africa.
Year after year, family groups get bigger and, as they do, the number of roosts
they build increases. Families might have as many as 14 individuals, so the
birds need to build multiple roosts, including a few “spares”.
There’s something intriguing about these roosts. Sometimes different families
set up territories next to each other, in trees as close together as 10 metres.
How do you tell families apart? By their roosts. Some families build roosts
that are very long, with long entrance and exit tubes; others will build roosts
that are much shorter, with hardly any tubes. Essentially, it looks like
different white-browed sparrow weaver families have different architectural
styles. Why?
To find out, we studied more than 400 roosts built by 43 families in the Tswalu
Kalahari Reserve in South Africa’s Northern Cape province. We confirmed that
the roosts and nests built by groups that live next to each other have their
own architectural style, and that environmental, physical or genetic attributes
of these different family groups do not influence the structures’
configuration.
We think that the birds’ building behaviour and the shape of the structures
might be the result of social interactions. Animals often learn from each other
how to do things, whether it is how to use tools (chimpanzees), how to sing the
correct song (some bird species, humpback whales), or how to exploit new food
resources (cockatoos). Learning from others within a group often results in
animals showing group-specific behaviours, or animal cultures. In this sense
animals, like humans, develop their own cultures."
Cheers,
*** Xanni ***
--
mailto:xanni@xanadu.net Andrew Pam
http://xanadu.com.au/ Chief Scientist, Xanadu
https://glasswings.com.au/ Partner, Glass Wings
https://sericyb.com.au/ Manager, Serious Cybernetics
