Not Exactly Rocket Science

South African wildlife – Weaver birds

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Weaver birds are the artisans extraordinaire of the bird world. As their name suggests, they fashion intricate nests out of plant material, carefully threaded and woven into a solid structure. All of it is done, quite literally, without lifting a finger.

These birds were all building nests in a tree outside a delightful winery called Delheim, which does an exceptional line of dessert wines. While my wife was inside sampling them, I was outside snapping away at this colony.

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The males are the ones who do the weaving, and their efforts advertise their skill and quality to potential mates. By picking the best structure, a female gets not only the most comfortable home but some assurance about the genetic standards of the home-maker. In the picture below, the nest on the far right is one of the most complete. The long downward-pointing entrance tube is an anti-thief feature, and it’s the last to be added.

South Africa is home to many species of weaver birds that are distinguished by relatively small differences in the size of their yellow and black markings, the colour of their eyes and so on. If anyone wants to take an educated stab as to what species these are, be my guest.

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Comments

  1. #1 Lilian Nattel
    January 10, 2010

    Fabulous photos and especially engaging given the frost and snow outside my window!

  2. #2 chezjake
    January 10, 2010

    Great photos, Ed.

    Your text seems to have become garbled in the second paragraph.

  3. #3 Ed Yong
    January 10, 2010

    Gnnh… stupid cut-and-paste. Fixed now.

  4. #4 sara
    January 10, 2010

    Wine and weavers! You surely have found heaven.

    Many of the Orange weavers lay beautiful bluish eggs. Whenever I meet South Africans, I ask them if they know the color of the eggs of weavers. The results of my survey suggest that this knowledge is as well known as the color of (American) Robin eggs is for Americans.

    By the way, they look like Cape Weavers (Ploceus capensis), but it is so shady in there, so I might be wrong about the colors.

  5. #5 David Hilmy
    January 10, 2010

    Sara, I think you have the bird ID spot on!

    The breeding males have olive-brown upperparts, yellow heads and underparts, with a brown to orange wash on the face and throat (photo 2)- another key mark is the white iris (photo 1)

    I suspect, because of the location (Delheim is in Western Cape province), that this is the western subspecies, the nominate Ploceus capensis capensis, with records indicating that olivaceus is more likely found in Kwazulu-Natal, and the third subspecies rubricomus also in Kwazulu-Natal and northwards to the Transvaal.

  6. #6 David Hilmy
    January 10, 2010

    By the way, with reference to egg color, you might find this particular study an interesting read- although primarily focussing on the Village Weaver (Ploceus cucullatus), comparisons to the species above and discussion on the evolution of their eggs’ color in response to brood parasitism and solar radiation is fascinating- it may be that the Cape Weaver’s slightly darker blue-green (and also that of the Red-headed Weaver, Anaplectes rubriceps) may be a reflection of the ancestral egg color of the Village Weaver prior to cuckoo parasitism.

    Lahti, D.C. Population differentiation and rapid evolution of egg color in accordance with solar radiation. The Auk, 125(4):796-802, 2008

  7. #7 DD
    January 10, 2010

    Humans can tie knots with the fingers, some can tie knots in cherry stems with the tongue. Hagfish can tie themselves in a knot to clean off slime. Tasmanian sharks tie their egg cases in a knot around vegetation (or the currents do). Great apes can interweave branches but AFAIK can’t tie knots. Monkeys never tie knots. Do weaverbirds tie true knots using the beak and feet, or are they limited to over/under weaving?

  8. #8 David Hilmy
    January 10, 2010

    @DD #7, absolutely yes, they do make real knots!

    Take a quick look at this little video on the Spectacled Weaver, Ploceus ocularis.

  9. #9 David Hilmy
    January 10, 2010

    (by the way, I understand that gorillas do indeed tie binding knots- granny knots as well as square (reef) knots, when they use vines to secure their nests… and although probably imitated by keepers, some chimpanzees and orangutans have been observed both tying and untying knots)

  10. #10 David Hilmy
    January 10, 2010

    LOL @ me #9 “imitated by keepers” is probably a truism, but I meant to write “imitating keepers”!

  11. #11 sara
    January 11, 2010

    Thanks, David Hilmy, for the link. I am totally in love with little blue eggs1, 2

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