NATCHEZ NATURALIST NEWSLETTER:
June 22, 2003
This species mostly overwinters in Mexico and Central America, south to Panama. Its summer distribution is strange. In the US the main breeding ground is Texas, Oklahoma and Louisiana, with us at the edge. Then there's another breeding center in southern South Carolina and eastern Georgia. They are absent in a large area centered around Alabama and I'm not sure why that would be so. Most birds, if they breed here, would also nest throughout the Deep South. You can see a map of their two-centered summer distribution at www.mbr-pwrc.usgs.gov/bbs/htm96/map617/ra6010.html
Their call is a lot like the closely related Indigo Bunting's, except that instead of being a warble consisting of strung-together phrases of two, it's a flow of single notes. You can hear it at www.mbr-pwrc.usgs.gov/id/htmwav/h6010so.wav
The Giant Swallowtail, the very similar Thoas and female Tiger swallowtails are the largest of all North American butterflies. The Giant's wingspread reaches 5.5 inches across (14 cm), though mine is only about 4.5 inches across. When the Giant is at rest with its wings folded above it you see the wings' mostly yellow undersides. However, when the butterfly holds its wings flush with the ground, from above you see black wings with yellow bands.
Those yellow bands arrange themselves across the butterfly's back in a pattern suggesting yellow lips of a smiling mouth. This pattern surely is no accident. Just imagine how unnerved a predator might be approaching the butterfly from above, suddenly to be confronted by a gaping mouth. You can see a picture of the same butterfly who visits the spot next to the barn-office at the top of my Lepidoptera Page at www.backyardnature.net/lepidopt.htm. That picture and all the others on the page were taken by Newsletter subscriber and neighbor Karen Wise of Kingston.
The Giant's caterpillar stage looks exactly like a moist bird dropping. If you have citrus trees around your house you might look for them there, for that's what the caterpillars feed on. In fact, in certain orange groves Giant Swallowtail caterpillars are considered a serious problem, and people spray to control them.
I'm glad to be sharing my space with such a gorgeous species. However, when I see him flitting around I feel a certain pang of embarrassment. That's because during the first days of his visit I misidentified him as the more familiar Tiger Swallowtail. It hadn't even occurred to me that the Giant might live here, so each time I saw a large, yellow butterfly I just called him a Tiger and went my way. It took my nature- photographer friend Jerry Litton of Jackson to bring the Giant's presence to my attention.
It just goes to show that even when you make a special effort to stay alert, the mind gets lazy. It's just human! So, the Giant Swalowtail reminds us that to get the most of life, every moment we must struggle to see things freshly, to rethink our assumptions, and always be expecting something new.
A native of South America, this vervain is a weed in the US Southeast and southern California. It's an annual plant, so you can see how vigorously it's grown to be so tall already this season, and to mantle some areas in pure stands. It's amazing that such a large plant comes from a seed less than a tenth of an inch long (2.5 mm), and it's also amazing to see how many seeds one plant produces. This fall and winter, what a seed-eating bounty this species will offer to thick- billed Cardinals, sparrows and buntings. I expect to have even more White-throated Sparrows here than at Laurel Hill, and that prospect pleases me enormously.
Despite its beauty and sweet perfume, it's a wonder the species isn't on Mississippi's "List of 10 Most Invasive Weeds." It is indeed a serious, non-native weed invading our fields and forests, shoving aside certain of our native species. It even grows at water's edge along Sandy Creek, as pretty and as alien as it can be.
Notice that above I spoke of powderpuff-like "flower clusters," not powderpuff-like "flowers." That's because the tree's pink, powderpuff-like items are actually several flowers clustered together. If you have a "Mimosa" in your yard you might go look at a powderpuff and see what's what. Each powderpuff consists of a dozen or so actual flowers. Each flower bears 20 or more very long, pink stamens (the powderpuff's "fuzz), and each stamen is topped by a tiny, yellow, pollen-producing anther. The pistil's style is similarly very long and slender, and easy to confuse with the surrounding stamens. The stamens arise from a tiny, cream-colored, cuplike thing with five teeth. That's the corolla, which in most flower types is the large, colorful part. I provide close-up pictures of these details at the bottom of the page at www.backyardnature.net/fl_test.htm
Since future editions of this newsletter will chronicle our steps toward realizing a community based on permaculture here, we should be clear about what permaculture is. Here is one of my favorite definitions:
When I look at that old, exhausted field with all its briars, weeds and lanky volunteer Loblollies, and call to mind the vision we have of a congenial, mutually supporting mingling of gardens, orchards, ponds, woodlots, chicken and goat pens, solar panels, windmills, homes for people... it's easy to get a sinking feeling in my stomach just thinking of all the work to be done.
But, then, when I try to think of anything else I'd rather be doing anyplace on Earth, I can't imagine it. If I can exit this life having improved the soil on just one spot of the planet, having planted a few trees and been responsible for contributing a bit more oxygen to the air and fixing a bit of carbon, and feeding a few people with nutritious, tasty food, and inspiring them to think healthy, generous thoughts, I believe I will have accomplished something beautiful and good, and I'll be content.
For an in-depth look at what permaculture is all about, go to http://attra.ncat.org/attra-pub/perma.html
If Painted Buntings are so brilliantly colored, then birds must not be color blind, right? In this year's May 18th Newsletter, we saw that the dog's world consists of yellows, blues, and grays, but no reds or greens. So, do birds also have a toned-down color perception? Are the male Painted Bunting's colors wasted on other birds?
It turns out that most birds apparently see a broader spectrum of colors than humans do. In most instances, bird color vision is to human color vision as human color vision is to dog color vision: Though color vision among birds varies from species to species, in general the human's perceived world isn't nearly as colorful as a bird's.
As noted in the May 18th Newsletter, in human eyes rods (for seeing black & white in dim light) and cones (for seeing color with strong light) translate light into electrical impulses the brain can understand. Well, human eyes have about 10,000 cones per square millimeter while some birds may have up to 120,000 per square millimeter! This explains why hummingbirds may be able to spot red flowers from over half a mile away.
Moreover, human color vision results from blending input from cones sensitive to three colors -- red, green and blue. Bird cones appear to be sensitive to five. Beside red, green and blue, they have a pale yellow and a wavelength approaching or actually being ultraviolet.
What must it be like to behold not only the colors we see, but also to perceive clear into the ultraviolet zone? A recent study showed why this talent might be useful to hawks and falcons searching for rodents above fields.
It happens that rodents mark their runways with urine and feces, and this excreta is visible in ultraviolet light. In tests, wild Kestrels (what we sometimes call Sparrow Hawks) brought into captivity were able to detect vole and mouse excretion in ultraviolet settings. Therefore, you can imagine a Kestrel patrolling high in the sky scanning acres and acres of fields and pastures for rodents. He's able to see rodent runways highlighted by urine and feces glowing in ultraviolet light, so instead of focusing on every part of the field equally, he's just watching those runways, and paying special attention to busy intersections.
Maybe you've seen the pretty iridescence that plays over the Starling's black feathers. Tests show that female Starlings prefer those males whose plumage reflects the most ultraviolet light. If you filter ultraviolet light from the light illuminating a male Starling, then the female chooses her mate according to some other criterion. Therefore, when in nature a female Starling looks at a male, she sees much more than a black bird with a bit of iridescence. She sees a potential mate decked in rainbow-plus togs, positively shimmering with visual hues we humans can't imagine.
Add to this the fact that there's good evidence that migratory birds can "see" the magnetic field. This "magnetoreception" may actually be visual, too. In 2000 T. Ritz et al used chemical experiments, physics theory and 3-D computer modeling to show that part of a bird's optical system could be affected at a molecular level by weak magnetic fields. Thus when a bird looks into the sky, maybe it sees something like perpetual northern lights as the Earth's geomagnetic field shifts and folds upon itself.
When I'm in the office nowadays with the Painted Bunting singing outside, I think about these things. I imagine what kind of world that bird must be seeing and how glorious it must look. I wonder if maybe that's why so often a bird seems to be singing for no good reason at all, singing just for joy?
What a shame that now nearly all our migrant songbird populations are collapsing because of human destruction of their habitat. What an irony that a species with only three colors to work with destroys so cavalierly the homes of a whole rainbow of species loving the Earth in five colors. Maybe if we humans had evolved more sophisticated photoreceptors in the backs of our eyes we wouldn't be so destructive, would find joy less in the consumption of goods and the gathering of prestige and power, than in the beauties of everyday life.
There's a lot more about bird vision at www.biology.eku.edu/RITCHISO/birdbrain2.html
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