Design of Life Update: Birds

Illustra Media’s Design of Life documentaries only began to explore the marvels of life. In this entry, we look at more wonders among birds.

Eggs come in a variety of sizes and shapes, as shown in a rapid-fire series in the Illustra film. In an “Egg Mythbuster” piece, Phys.org explains why some eggs are pear-shaped. The beautiful spotted eggs of the guillemot, long prized by egg collectors (a practice now banned), are shaped to prevent breakage when other birds lands on the rocks where they build their nests. In a video clip, Professor Tim Birkhead (U of Sheffield) describes guillemot eggs as “one of the most beautiful and extraordinary eggs in the bird world” because of their varieties of colors and markings. “It’s a testament to the powers of natural selection,” he adds, personifying the Stuff Happens Law with creative genius.

Aside from that slip, Birkhead shows spectacular drone shots of the sheer cliffs where the seabirds rear their young. He then tells about the “climmers” of the 19th century. Their goal of collecting unusually-colored guillemot eggs had the effect of making them “citizen scientists” who had learned more about the birds’ biology than professional scientists of the time. His main point, though, is to explain the egg’s shape, which may have “a variety of reasons” behind it. After debunking two popular myths, he gives his favorite hypothesis, which has to do with the strength of the eggshell. It is thickest on the long axis which is the most subject to breakage as the mother incubates it. If another bird crash lands on top of her, the egg will likely survive the blow. This still does not explain the colors and markings. Birkhead’s new book is titled The Most Perfect Thing after a descriptive phrase by Thomas Wentworth Higginson (1823-1911), American abolitionist, who said,

‘I think that, if required on pain of death to name instantly the most perfect thing in the universe, I should risk my fate on a bird’s egg’ — Thomas Wentworth Higginson, 1862

Update 3/10/17: Speaking of guillemots, Science Daily just posted a possible explanation for why guillemot chicks leap hundreds of meters off the cliffs where they were reared into the water before they are ready to fly. Their fathers of the guillemots (also called murres) guide them on this “remarkable leap” that has baffled scientists. Many hours of observation showed that the fathers work very hard providing food for the chicks up on the cliff for up to 5 to 7 weeks. As soon as the chick is able, the father guides it down to the sea where it can learn the art of feeding itself. Scientists “discovered that chicks at sea grew at roughly twice the speed of those at the colony, because the murre fathers no longer needed to fly back and forth to the colony to feed them.” The classic documentary Winged Migration includes a scene of a guillemot chick doing the leap, landing with a splash, to the relief of the exhausted father.

Embryos. In the sequence on a developing chick embryo in the Illustra film, scientists describe the “elaborate dance” that takes place, with molecular machines doing jobs, moving systems, and committing parts of the embryo irreversibly toward their roles in the adult. A new paper in PLoS One describes just one stage in the 21-day period when gut motility (peristalsis) begins— i.e., the muscle contractions that will move food through the digestive tract. They watched the sequence unfold on days 6 through 9.

We found that the emergence of an uninterrupted circular ring of smooth muscle correlated with the appearance of propagative contractile waves, at E6 in the hindgut and midgut, and at E9 in the caecal appendix. We show that peristalsis at these stages is critically dependent on calcium and is not mediated by neurons as gut motility is insensitive to tetrodotoxin and takes place in the hindgut in the absence of neurons.

“Our work sets a baseline for further investigations of motility development in this important animal model,” the four authors say.

Chick embryo, from Flight: The Genius of Birds (Illustra Media)

Hummingbirds have a flight stabilization system in their neurons. Current Biology has a paper by M. R. Ibbotson about how it works.

The pretectal visual motion processing area in the hummingbird brain is unlike that in other birds: instead of emphasizing detection of horizontal movements, it codes for motion in all directions through 360°, possibly offering precise visual stability control during hovering.

Interestingly, the Allen’s Hummingbird has a subspecies that migrates and another subspecies that does not. Phys.org says that birders miscounted the two and came to a wrong conclusion that the hummingbirds were in decline, when actually the non-migrating kind were doing quite well at backyard feeders and parks in southern California. The Allen’s hummingbird was on conservation watchlists because it was thought to live only on the Channel Islands offshore. The Audubon Society’s eBird tool allows citizen birders to record their observations. This allowed Christopher Clark to publish corrected statistics in The Auk , a journal of the American Ornithological Society. He says that Channel Island species colonized southern California urban areas sometime before 1966. eBird.com reported this story on its news page, with photos of the bird and maps where they were observed.

Collective Motion is performed by many birds, like the starlings shown in Flight. Hummingbirds, too, engage in “group mobbing” to scare off owls and other predators by divebombing them, says Science Daily. Whether this is a form of sexual selection to impress females seems dubious, since it would appear difficult for a female to distinguish a single male in a crowd. Even if she could, will she connect his prowess with fatherhood skills? Instead, it may “teach younger birds to distinguish friend from foe” – a function not necessarily independent of giving the girls a good air show.

Starling murmurations, from Flight: The Genius of Birds (Illustra Media)

Migration is undertaken by many bird species in addition to the Arctic terns shown in Flight. The behavior may play more of a role in the general ecology, though, than thought. Phys.org says that wintering ducks spread plant seeds from one body of water to another, thereby connecting wetlands to each other. This helps prevent habitat loss and fragmentation of ecological zones, and thus improves biodiversity. Some plant seeds move through the birds’ digestive tracts unharmed; plants, therefore, can use birds as a form of air mail for seed dispersal.

Dinosaur-to-Bird Evolution was “not as straight as thought,” Phys.org says —as thought by evolutionists, that is. Paleontologist Stephen Brusatte debunks various myths of bird evolution, particularly the idea that one can draw a straight line from a dinosaur to a bird in the fossil record. Put his statements in your philosophy pipe and smoke it; do evolutionists really have a story of bird evolution more firm than mere suggestions that stuff happened?