NATCHEZ NATURALIST
NEWSLETTER:
from the woods near Natchez, Mississippi, USA

March 31, 2002

MAYAPPLE RESEARCH
A couple of years ago Kathy the plantation manager read an article in the local paper about research at Mississippi State in Starkville dealing with Mayapples, a forest wildflower in the Barberry Family. Also called Mandrake, it's PODOPHYLLUM PELTATUM, and you can see a picture of a flowering plant at www.csdl.tamu.edu/FLORA/mi02/mi02024.jpg  

Kathy wrote to the University saying that we had lots of Mayapples here on the plantation. A researcher wrote back saying she'd like to visit us to see them. So last spring two Ph.D.'d investigators made three visits here. They established permanent plots so they could monitor population dynamics and they collected leaves in some plots to see how that affected the plants' health. Now the Mayapples are up again and flowering, so on Tuesday the researchers were back with their notebooks, GPS units and calculators.

The idea is to see if Mayapples might become a cash crop for Mississippians. Mayapple is known to be a highly poisonous (deadly) plant with medicinal value. Chemicals derived from it are today used in anti- cancer medicines, and the Indians were known to use it for many purposes. For example:

"Cherokee Indians used the plant for an anti- rheumatic, cathartic, dermatological aid, ear medicine, insecticide, and laxative. Other Cherokee used the root as a purgative, vermifuge, for the treatment of warts and as an anthelmintic." You can read this and a lot more about the wonders of Mayapples at http://www.siu.edu/~ebl/leaflets/mayapple.htm

The Mayapple's waxy-white flower, about 1.5 inch (4cm) across, produces a "May apple," a greenish-yellow fruit which when fully ripe tastes good and is not dangerous at all. However, the critters around here must like them as much as I do because I've never found a single ripe fruit here, despite the plant's abundance.

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HORRIBLE THISTLE, POPULAR NEIGHBOR
Horrible Thistle is also called Bull Thistle, but that name is shared with other thistles. The plant I'm talking about is CIRSIUM HORRIDULUM, whence comes the "horrible."

Several of these knee-high, thick-stemmed, supremely spiny, violet-flowered thistles occupy the middle of an old, grassed-over logging road running near my camp. Because of its mind-boggling spiniferousness and general squat, tough-looking, almost barbaric look, it's one of the most striking plants on the plantation. You can see a picture of a flowering head with enough spines to give you a general idea about its appearance at www.rlephoto.com/botanicals/thistle_yellow01s.jpg

These plants are always being visited by Leaf-footed Bugs, LEPTOGLOSSUS PHYLOPUS, of the true-bug family, the coreidae. The bugs congregate on the thistles' spiny flower-heads like Japanese Beetles on a Rose and about a third of them are usually copulating. Immature Leaf-footed Bugs thrive on thistle, but the adults give grief to citrus and Pecan trees, and other crops. On Pecan trees they cause black pit and kernel spot diseases. You can see this bug and read all about it at creatures.ifas.ufl.edu/orn/leaffooted_bug.htm

A certain female Tiger Swallowtail Butterfly spens so much time on the blossoms that the bottom parts of her wings are torn ragged by the plants' spines. You can watch her fluttering there, the spines puncturing and tearing her wings, but she seems unable to resist the thistles' nectar, returning again and again.

By the way, you may not know that while male Tiger Swallowtails are those large, yellow-and-black butterflies we often see, the females are mostly black. Her appearance has evolved to mimic the Pipevine Swallowtail, which birds find too disagreeable in taste to eat. Birds learn to avoid eating Pipevine Swallowtails, and in so doing stay way from female Tiger Swallowtails. Several good pictures and a lot of interesting information about Tiger Swallowtails is at www.oznet.ksu.edu/johnson/hort/Butterfly/TigerSwallowtail.htm

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GRANDMA'S WHITE-HEADED GRACKLES
Wednesday morning my Grandma Taylor in Calhoun, Kentucky called saying she had seen a Grackle with a white head "looking just like a little Bald Eagle." Like a lot of people in my family, Grandma is a very serious feeder of birds, keeping her rocking chair next to a window so she can see her visitors, and she goes through many bags of seeds each winter.

Grackles as well as European Starlings have learned not only to visit suburban and small-town bird-feeding stations, but also they swarm over agricultural fields, gathering grain missed by machines. For this reason I'm not surprised with Grandma's discovery. I myself have seen Starlings and House Sparrows with white patches or sometimes with just one white wing- feather.

A hint as to why white feathers on otherwise dark birds shouldn't be too surprising lies in the fact that when you compare domesticated animals with their wild relatives, the wild stock all look alike, while the domesticated ones are more variable in their appearance. Wild doves have specific plummages, but semidomesticated park pigeons show all colors and patterns. Zebu cattle and other cattle types in Africa have fixed appearances, but among the cattle I jog by each morning, some are rusty-red, some are blotchy, etc. Same with dogs and cats.

You can understand what's happening here by visualizing a wild dove who develops a white feather because of natural random genetic mutation. The white feather makes the dove more visible to hawks, is eaten, and thus the general tendency to produce an occasional white feather is removed from the dove gene pool. On the other hand, if a park pigeon living on handouts acquires an extra white feather, what of it? That white feather will not betray the bird's presence to park-hawks.

Starlings and Grackles in their big flocks out in the fields and around bird-feeding stations are getting close to being like park pigeons. The occasional white feather or white head among them is a sign that nowadays they are not needing to worry much about hawks. Waste grain enables large flock size, and in a large flock someone always notices a hawk approaching, so hawk attack is less likely, and therefore Mama Nature loosens up on her dress code.

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BROWN-HEADED COWBIRD MORALITY
Thursday morning as I prepared my campfire breakfast, four blackish, dumpy-looking birds landed in the top of a nearby Pecan tree. They made squeaky gurgling calls and fluttered in a curious way so even without binoculars I knew I had four Brown-headed Cowbirds. You can see this bird and read a lot about it at birds.cornell.edu/bfl/speciesaccts/bnhcow.html

I watched as three males orbited around a female displaying. During the "Bill-Tilt Display" a male would lift his head and point his bill skyward. This would often be followed by the "Topple-Over Display," during which the bird would fluff his body feathers, arch his neck, spread his tail and wings, and sort of lurch forward, sometimes issuing the gurgling song. Apparently these displays excite females, and probably females choose to mate with males doing the best job. The above Web address goes into more detail about these and other cowbird displays.

Female cowbirds do not lay eggs in their own nests. Being careful to go unobserved, sneaking quietly through undergrowth or among dense leaves, they look for the nests of birds of other species. Often they locate nests still under construction. Then the female cowbird watches the nest until egg laying begins, and one dawn she sneaks in, removes and sometimes eats the nest-owner's egg, and lays her own. If only one "host" egg is present, she does not remove it, apparently because doing so might clue the nest owner that something is amiss, and the nest might be abandoned.

Not only do cowbird eggs usually hatch one day ahead of the host's eggs, but also cowbird nestlings typically are larger, are more aggressive in begging for food, and grow faster than the host's own young. Even when the cowbird fledgling grows much larger than the host mother herself, the mother just doesn't catch on that there's a problem. You can see a picture of tiny warbler mother feeding a huge cowbird fledgling at www.pwrc.nbs.gov/resshow/hahn1rs/hahn1rs.htm

Of course this is hard on "host" families. Before humans began cutting up the landscape, cowbird "nest parasitism" wasn't as important as it is now because cowbirds in most places tend to focus their activities in open areas and forest edges. However now humans have broken vast forests into tiny plots and there are so many access roads that many remaining forests consist of nothing but "ecological edges." Cowbird nest parasitism is a very serious problem contributing to the ongoing collapse of many bird populations. Species hurt particularly hard include the Song Sparrow, Chipping Sparrow, Eastern Phoebe, and Northern Cardinal.

How can Mother Nature tolerate such a free-loading species?

Maybe we just have to recognize that Nature rejoices over diversity to the same extent that She doesn't really care much whether individuals like you and me get exactly what we want. Nature exults in the robust feeling embodied in the music, not in the destinies of us individual notes comprising the score.

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THIS WEEK'S MIGRATING BIRDS
Here are the migratory species I identified on Friday, March 29:

So the hummingbirds have arrived; and isn't it interesting that I never see American Robins?! Last week I listed 13 migratory species but this week there are 27. Most of the difference is because of last week's icy wind but, still, a lot of birds have arrived this last week. And migration is just beginning...