Here are a few videos of the amazing behaviors of some birds—birds that sew and birds that weave. After you see these, perhaps you won’t see the term “birdbrain” as pejorative.
Here’s Orthotomus sutorius, the Common Tailorbird (not common in any way), a warbler-like passerine that lives in tropical Asia. It has a stunning way of building a nest. First it takes a big leaf, pierces it with holes, and then, using plant fiber, sews the edges of the leaf together, making a cradle or cup inside which the real nest is constructed. It’s a way of both protecting and camouflaging the nest.
The first video below was sent to me by Bruce Lyon, who shows it in his ornithology classes at UC Santa Cruz. He was responding to my puzzlement about how this behavior evolved. It’s a certainty that the instructions for building this nest-cradle are genetic, instilled in the bird’s brain by natural selection. But for that to happen, there has to be some beginning behavior that is adaptive, and then that evolved into the complex procedure we see today after a gradual and sequential refinement of that initial behavior. For natural selection to have built this, each step of the evolutionary process had to confer a reproductive advantage on the bird. I couldn’t figure out what the initial step was, for it would have had to lead to piercing the leaf and sewing it together; and how did that evolve? I have no idea.
I suppose the ID morons could use this as an example of “irreducible complexity”, for the behavior doesn’t appear to be adaptive until the complex procedure has already evolved. But I’ve learned enough in my years as an evolutionist to realize that this is a limitation not on nature, but on our imaginations. So many behaviors whose evolution has appeared mystifying have, upon later study, revealed incipient stages that one could envision evolving via natural selection into something more complex. (Darwin talked about this in The Origin when pondering the construction of beehives with hexagonal wax combs.)
Perhaps readers of an ornithological bent can posit how the tailorbird behavior got started. Regardless, what we see now is something amazing.
Here’s a longer video (nearly a half an hour) if you have the patience and want to see the whole process:
Weaverbirds don’t sew but weave, but that’s no less remarkable, for their weaving involves tying knots—good ones. This is easier to envision; as Bruce said, “The knots are easier for me to think about incipient stages — lots of birds wrap strands of vegetation around branches to anchor the strand.” And it’s the males who build the nest, trying to lure females with their architectural prowess.
And voilà: we get this (there are three videos; the first emphasizes knot-tying:
Here’s the whole process, starting with the knots and continuing with the weaving.
More knots and weaving.