THIS WEEK at HILTON POND
22-31 May 2003
Installment #174---Visitor #

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NIGHT OF A THOUSAND LEGS

As diurnal creatures who snuggle up in bed at night, it's sometimes easy for humans to forget that the world of nature may be just as active after sundown when we can't see what's going on. Creatures such as Southern Flying Squirrels and Bobcats have eyes far more sensitive to light than ours, and they navigate the midnight woods at Hilton Pond Center as easily as we do at noon. Great Horned Owls swoop through night skies, using acute hearing to find their prey, and Red Bats certainly have no trouble echolocating flying insects and gobbling them down on the darkest of nights. Fortunately, despite our poor biological adaptations to nocturnal activity, humans were able to use our brains to invent flashlights, and this simple tool allows any of us to journey forth after dark to see what's out and about.

All text & photos © Hilton Pond Center

Such was the case this week when we were up well before dawn and walking along one of the Center's trails. Our flashlight of preference is a headlamp that frees both hands and allows us to aim the beam exactly where we're looking. As we rounded a bend in the trail, we pointed the light downward and spotted something moving slowly across the path. It looked like a shiny brown tube, but there was little doubt about its identity: it was a "thousand-legger," or millipede.

Despite their name, millipedes don't really have a thousand legs, but they seem to. Most species bear two pairs of legs on all but the first several segments--each of which has only a single pair; the photo below posterior shows quartets of legs on the millipede's posterior segments. Since the specimen we found at Hilton Pond Center had 48 segments (not counting the head and tail) that means, if we calculate correctly, this particular millipede had, hmmm, let's see, 48 minus 5 segments with only one pair each is 43, times 4 is 172 legs, plus 2 legs times 5 segments is 10, equals, hmmm, a total of 182 legs. It's hard enough for us to just count these appendages, so it's a real wonderment that a millipede is able to coordinate them all and move about so effortlessly by night on the forest floor.

Millipedes are in the Diplopoda, the invertebrate class whose name actually translates as "double feet" and refers to those segments with two pairs of legs. "Thousand-legger" millipedes are distantly related to the centipedes (Class Chilopoda), which are "hunnert-leggers" with only a single pair of legs per segment. Centipedes are more likely to be encountered by humans, since they often hang out in basements and in spring have been known to migrate in large numbers up from the cellar, across the living room, down the hall, and out into the night . . . and sometimes back. (In fairness, we should mention that a few house-loving millipede species exhibit this same behavior.) Centipedes--which prey on insects and spiders--have menacing pincer-like mouthparts that in large specimens are capable of inflicting a painful bite and injecting poison. Curiously, these poison jaws are really modified legs; "Chilopoda" loosely translates as "lip foot."

Our millipede, a far gentler organism, doesn't nip but defends itself in a quite different manner, as we were reminded when we picked it up on the trail. If disturbed most millipedes protet their heads by curling into a tight spiral and often produce a fecal pellet (below right); if that fails to dissuade potential predators, some millipedes excrete from pores on their sides an repugnant fluid that-- according to some experts-- is strong enough to kill an insect placed in a container with the millipede. To our nostrils, the potent chemical smells slightly sweet and in some cases reminds us of wild cherries--not surprising since the millipede juice is reported to contain hydrogen cyanide, a compound also found in cherry leaves. (NOTE: Experts claim some millipedes excrete benzoquinones and a assortment of other chemicals other than cyanide.) And--as we accidentally found out while handling this week's millipede for photographic purposes--the fluid can discolor human skin to about the same shade as brownish nicotine stains we've seen on the fingers of heavy smokers. We were pleased to note, however, that our specimen was NOT one of those whose excretions irritate the eyes or cause epidermal blistering. Despite their noxious fluids, millipedes are a favorite food of toads, lizards, birds, small rodents, and some predatory insects.

The majority of the 1,400 known species of North American millipedes dine on decaying vegetable matter and fungi and play a crucial role in decomposition of leaf litter and nutrient cycling. Some species browse on roots, stems, or leaves of live plants and can cause problems in the garden, while a very few millipedes have modified mouthparts that allow them to take live prey such as insects and earthworms. As demonstrated by our encounter this week, most millipedes are creatures of the dark that forage by day beneath dead leaves and occasionally venture forth at night. Outdoors they overwinter as adults and emerge in spring, perhaps using their sensitive antennae (top photo and below right) to scan the air for some of that enticing hydrogen cyanide and/or benzoquinone given off by a prospective mate. When a partner is encountered, copulation ensues, with sperm being guided into the female by modified legs on the male's seventh segment; the specimen we found was a female with all legs being similar in structure (above left). After mating, the female goes off to lay her clutch of up to 300 white eggs in a small soil depression that she sometimes defends. Eggs hatch within a few weeks to produce tiny millipedes with only three pairs of legs. As the offspring grow, a few new pairs of legs are produced with each successive molt. Individual millipedes can live for several years in a terrarium; folks collect, raise, and trade these multi-legged invertebrates, some of which are even sold in pet shops.

The specimen we found this week at Hilton Pond Center is Narceus americanus; at four inches long and a half-inch in diameter, it is by far the largest millipede in the Carolina Piedmont. In comparison, the common Garden Millipede, Oxidus gracilis, is less than an inch in length and only an eight of an inch wide.

N. americanus, which seems to have no common name, occurs across much of the eastern U.S. and into southern Canada; it is identifiable by a dark purplish-brown body with a thin band of red on the rear edge of each segment. Like most millipedes, it has two large compound eyes made up of many tiny light-sensitive dots called "ocelli" (right), and its mouthparts are relatively small. No one knows how old this particular species might be, but it comes from ancient lineage. The earliest millipedes date back 420 million years, making them the oldest surviving group of terrestrial arthropods and almost twice as old as the earliest dinosaurs. Their general body structure has changed little since the mid-Paleozoic Era, which means millipedes have had plenty of time to work on coordinating those millions, er, thousands, no, hundreds of legs that help them navigate the trails by night here at Hilton Pond Center.

All text & photos © Hilton Pond Center

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Be sure to scroll down for an account of all
birds banded or recaptured during the period,
plus other nature notes of interest.


"This Week at Hilton Pond" is written & photographed
by Bill Hilton Jr., executive director of
Hilton Pond Center for Piedmont Natural History.

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BIRDS BANDED THIS WEEK at HILTON POND CENTER
22-31 May 2003

SPECIES BANDED THIS WEEK
Ruby-throated Hummingbird--2
American Redstart--1
White-eyed Vireo--1
American Goldfinch--3
Carolina Chickadee--3
Black-and-white Warbler--3
Acadian Flycatcher--1
Chipping Sparrow--1
Gray Catbird--1
Northern Cardinal--1
Tufted Titmouse--1
House Finch--1
White-throated Sparrow--1
Carolina Wren--1
Downy Woodpecker--3
Brown Thrasher--2

* = New species for 2003


WEEKLY BANDING TOTAL
16 species
26 individuals


YEARLY BANDING TOTAL
(2003)
44 species
571 individuals


BANDING GRAND TOTAL
(since 28 June 1982)
123 species
42,685 individuals


NOTABLE RECAPTURES THIS WEEK
(with original banding date, sex, and current age)

Ruby-throated Hummingbird (1)
09/04/02--2nd year female

American Goldfinch (1)
02/07/02--after 3rd year male

Eastern Wood-Pewee (1)
05/17/02--after 2nd year male

Pine Warbler (1)
04/15/02--after 2nd year female

Northern Cardinal (5)
05/30/98--after 6th year female
04/24/01--after 3rd year male
07/29/02--2nd year male
10/17/02--after hatch year male
11/23/02--after hatch year female

Eastern Towhee (2)
10/20/01--3rd year female
08/08/02--2nd year female

Carolina Wren (2)
06/30/01--3rd year male
05/27/02-- after 2nd year female

Tufted Titmouse (1)
06/17/02--2nd year male

Brown Thrasher (1)
10/07/02--after hatch year male

White-throated Sparrow
Common in winter across the Carolina Piedmont, this species is seldom seen after mid-May. The one banded on 27 May 2003 at Hilton Pond Center is an apparent late record--by ten days-- for the Carolinas, although five summer vagrants have been reported through the years.


OTHER SIGHTINGS OF INTEREST

--Another 1.2" of rain fell at Hilton Pond Center on 21-22 May, followed by a 3.25" frog-strangler on 22-23 May. Then there were unusual sunny-stormy-sunny-stormy epidoides on 25 May that netted another 1.4" of precipitation. Only seven days in three months has the pond itself NOT been flowing over its spillway--an unprecedented period of high water over the past 21 years. According to TV meteorologists in nearby Charlotte NC, this is the second-wettest May in history. We feel safe in declaring now that the five-year drought at Hilton Pond is officially over.

--Summer must be at hand. The first biting Deer Flies (above) and pore-burrowing Chiggers of the season made their appearance at the Center on 28 May.

All text & photos © Hilton Pond Center

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