We're back to our non-summer start time, 8:30AM, and 23
ramblers showed up for this comfortable morning.
Don Hunter's album for today's ramble is here.
Reading: Today's reading
is an excerpt from an address given by Aldo Leopold at the dedication of a
monument to the passenger pigeon. The last living passenger pigeon died in
captivity 100 years ago this month.
We are told
by economic moralists that to mourn the pigeon is mere nostalgia; that if the
pigeoners had not done away with him, the farmers would ultimately have been
obliged, in self-defense, to do so.
This is one
of those peculiar truths that are valid, but not for the reasons alleged.
The pigeon
was a biological storm. He was the lightning that played between two opposing
potentials of intolerable intensity: the fat of the land and the oxygen of the
air. Yearly the feathered tempest roared up, down, and across the continent,
sucking up the laden fruits of forest and prairie, burning them in a traveling
blast of life. Like any other chain reaction, the pigeon could survive no
dimunition of his own furious intensity. When the pigeoners subtracted from his
numbers, and the pioneers chopped gaps in the continuity of his fuel, his flame
guttered out with hardly a sputter or even a wisp of smoke.
Today the
oaks still flaunt their burden at the sky, but the feathered lightning is no
more. Worm and weevil must now perform slowly and silently the biological task
that once drew thunder from the firmament.
The wonder is
not that the pigeon went out, but that he ever survived through all the
millennia of pre-Babbittian[*] time.
*reference to the satirical 1922
novel Babbit by Sinclair Lewis
(From Aldo Leopold, On
a Monument to a Pigeon, in A Sand
County Almanac and Sketches Here and There, 1949, Oxford Univ. Press, p.
111 in the 1968 paperback edition.)
Each rambler received a printed sheet of paper that, when
folded according to instructions, results in an origami passenger pigeon. After
the ramble we folded our own miniature flock at Donderos'. Those of you who
weren't able to attend today's ramble can obtain your own origami passenger
pigeons from http://www.foldthe flock.org and while you're there view an
awesome animation of what a flock of must have looked like as they passed
overhead.
Parasites that change
their hosts behavior: Before we started I passed around a beech
 |
| Fungus infected spider |
|
leaf that
Emily and I found at the garden two days ago. On the underside of this leaf is
the body of a dead spider. Sprouting from the abdomen are the fungal spore
producing shoots, looking like the fingers of a dead hand. Fungi like this have
been seen in other arthropods, especially ants. Infected ants leave their nest
and climb up grasses and trees and then bite whatever they are on. They remain
there, locked to the plant by their jaws until they die. Meanwhile the fungus
is busy digesting their interior and sprouting its spore-dispersing structures
into the air. The ants typically are anchored to a place that is favorable for
the dispersal of fungal spores. We don't know if this fungus changed the
behavior of its spider host, but it is a possibility.
Today's route:
From the arbor down the walk through the Shade garden and into the Dunson
garden, then across the road to the White trail, up the power line and then
down the power line to the river; left on the orange trail past the privet
removal project and then back to the arbor via the orange spur trail.
Shade Garden
On the sidewalk through the Shade Garden there were many
hickory nuts that had been gnawed on by rodents. The large mockernut hickory nuts had very thick husks and some of their
diners had given up chewing through the husk to get at the nut inside. The pignut hickory nut has a much thinner
husk and we found several that had been successfully opened and the contents
devoured.
We also stopped to check on the witch hazels. Earlier in the spring we observed numerous galls on the leaves of the native
species (on the right side of the sidewalk if you're going downhill) and split
a few open to reveal they were filled with aphids. Today the galls remain on
the leaves but they are all empty. The aphids have flown away to an alternate
host plant where they will feed and lay overwintering eggs. Next spring the
eggs will hatch and the winged aphids will again seek out the witch hazel and
produce a new round of galls on its freshly emerged leaves. Mark your calendars
for next spring to see this exciting event.
 |
| Triangulate Orbweaver | |
While at the witch hazels we looked for the tiny flower buds
that are just now forming. Witch hazel blooms late in the fall, so we'll be
checking these plants often come October.
A rambler spotted a small spider web and at the center was
the spinner, a brownish spider with a prominent bright yellow triangle on its
abdomen -- a triangulate orbweaver.
Dunson Native Flora
Garden
 |
| Horsebalm inflorescense |
|
We ducked into the Dunson garden to check on the Horsebalm that we had seen last week.
It is now in bloom and, if you were expecting a fantastic floral display,
somewhat anti-climactic.
But standing next to the horsebalm was the stalk of a Jack-in-the-Pulpit, or, more precisely,
Jill-in-the-Pulpit, bearing brilliant red fruits. Red is a common color of
fruits that are bird
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| Jack-in-the-Pulpit fruits |
|
dispersed. The plant offers the bird a sweet, red treat
and the bird consumes the flesh that surrounds the seeds and then defecates the
seeds somewhere else, along with a drop of fertilized to get them started. It's
a win-win situation for both parties.
Some ramblers noticed a Downy Skullcap
in bloom and when we started up the road we found a Beautyberry with its clusters of bright purple fruits.
White trail
 |
| Microstegium and Beefsteak plant |
|
At the intersection of the White trail and road there was a
patch of dense vegetation made up of two species: Beefsteak plant, a mint, and microstegium.
Microstegium
(also called Nepalese browntop or Japanese stilt grass) is a terribly invasive
annual grass. It can flourish in low light situations and displace native
species. In addition to its direct effects and plant communities additional
impacts have recently come to light. A recent study, published in the journal
Ecology by two UGA researchers, shows that Microstegium has a negative impact on
American toads. (You
can read the paper here.) This study reveals that when microstegium invades
a habitat the number of wolf spiders increases. Wolf spiders are hunters. They
search their habitat for small arthropods which they attack, kill and eat.
Their prey also include their own species and this cannibalism helps to reduce
the size of the wolf spider population. So how does microstegium cause the
number of wolf spiders to increase? Because a patch of microstegium is so
dense, containing many stems, wolf spiders have a more difficult time finding
other wolf spiders. So more of them survive in a patch of microstegium. This
increase in spider density means that very small, recently metamorphosed toads
are more likely to encounter and be eaten by spiders, so there numbers decline.
This is an example of an "indirect" effect or a "knock-on"
effect: A causes B to change and the change in B has an impact on C. Ecosystems
are full of these kinds of effects. It makes knowing the effect of changing a
habitat so difficult to determine.
 |
| Pulling Microstegium |
|
Several of the ramblers immediately began to pull up the
microstegium.
Further along the White trail we found examples of Smooth
Sumac, Yellow crownbeard, River oats and purpletop grass.
How to tell the
wingstems apart. Wingstems are plants in the genus Verbesina; we have three species in the natural areas of the garden:
V. alternifolia, V. virginica and V.
occidentalis. Distinguishing them is pretty easy, but sometimes difficult
to remember. Here are the tricks I use to keep them straight.
Common Name
|
Scientific Name
|
Flower color
|
Leaf arrangement
|
Wingstem
|
V. alternifolia
|
Yellow
|
Alternate
|
Frostweed,
|
V. virginica
|
White
|
Alternate
|
Crown-beard
|
V. occidentalis
|
Yellow
|
Opposite
|
 |
| Wingstem | |
I have the most trouble associating the names with the
combinations of characteristics, so I use a mnemonic: V. occidentalis has opposite leaves (opposite and
occidentalis
 |
| Crown-beard | |
both begin with "o"; V. alternifolia has alternate
leaves (this is easy since alternifolia
means "alternate leaves"); V.
virginica is named for Virginia which is further north than Georgia and,
therefore, colder, so the plant has snow-white flowers and is called Frostweed.
I haven't come up with a good way to remember that Wingstem has yellow
 |
| Frostweed | |
flowers,
except by elimination (Frostweed is the only one that has white flowers, so if the plant has yellow flowers it's either Crown-beard
or Wingstem and you can tell them apart by their leaf arrangement. If you can
remember all this it might help build new neurons in your brain.
How do you tell if you're looking at a Verbesina? You need to look at the stem to see if there is a ridge
running the length of the stem on opposite sides. Unfortunately, some of the
Wingstems (using the term to refer to the whole group, not just V. alternifolia) have faint wings and
some individuals have them only on the lower or upper parts of the stem. Plants
are variable, so you have to examine the stem closely. Another characteristic
of the group is that the flowers are pretty skimpy. That's because only some of
the florets have a petal. Many of the florets are disk florets, and do not have
the strap-like petal.
You had to be there:
Some things in nature happen very quickly: a hawk attacks a bird on the feeder
in your yard. You have to be looking out the window at the right time or you'll
miss it. One of those events happened as I was walking with a couple of
ramblers on the Orange trail in the privet clearing section. One of them called
my attention to a large wasp that was hanging onto the end of a twig and
behaving very strangely. I took a closer look and realized that I was
 |
| European Hornet with prey |
|
seeing a
European Hornet, a very large wasp that has become naturalized in the United
States. It appeared to be holding something and I looked closer -- the hornet
was grasping a small Yellowjacket in the legs that were holding the twig and it
was manipulating the Yellowjacket to keep the sting away from its body. As I
watched it bent down and bit the head off the Yellowjacket and immediately flew
off. It had taken just a few seconds to subdue and kill the smaller Yellowjacket.
European Hornets construct paper nests, like Bald-faced Hornets do, but they
are built in cavities instead of on branches of trees. This Hornet was taking
the Yellowjacket back to its next to feed it to the larvae that are communally
raised in the nest. The typical nest
holds about 200-400 workers and a single reproductive queen. I'm sorry that not
everyone could see this exciting sight, but it was over too quickly. (Photo
of European Hornet with prey from Wikipedia.)
Upper power line
right of way Today we saw many of the same plants we saw blooming last week,
so I'm going to just list them here and write a little more about a few of them
later:
Flowering Spurge, Wild lettuce, Beefsteak
plant, Grass leaf Golden aster, Mountain mint, Rabbit tobacco, White crownbeard,
Elephant’s Foot, Wild Sensitive Plant, Yellow star grass,
Late-flowering thoroughwort (or boneset) and Slender ladies tresses.
Lower power line
right of way The plants seen on the power line
right of way between the road and the river were: Golden aster, Silver plume
grass, Late-flowering boneset, American Pokeweed, Camphor pluchea, Spotted St.
Johns Wort, Virginia button weed, Tall ironweed, Field thistle, Common evening
primrose, Climbing Hempvine, Daisy fleabane, Goldenrod, Small white morning
glory, Wingstem, and Leafy elephant’s
foot.
The critters we saw were: Gulf
fritillary caterpillar on passionvine, Gulf fritillary caterpillar in the act of forming a chrysalis; a Pearl crescent butterfly and a Carolina anole.
How a caterpillar
forms a chrysalis. The pupal stage of a butterfly is called a chrysalis;
that
 |
| Chrysalis half-way free from caterpillar skin |
|
of a moth, a cocoon. A cocoon is usually covered with silk spun by the
caterpillar and often has leaves or the hairs of the caterpillar imbedded in
it. (Technically, the
 |
| Gulf Fritillary caterpillar |
|
cocoon is the silken structure that surrounds the naked
pupa of the moth, but the term is casually used in a collective sense to refer
to both pupa and silken surrounding.) The pupal stage of a butterfly is naked,
like the moth pupa, but it is often brightly colored and decorated or assumes
cryptic shapes so that it resembles a dead leaf. The chrysalis of many butterflies hangs head
downward, suspended from a button of silk in which the posterior end is hooked.
Several ramblers were lucky to catch a Gulf fritillary butterfly in the final
stage of chrysalis formation . It begins with the caterpillar spinning a button
of silk. The caterpillar then clasps the silk button with its terminal abdominal
legs and hangs head downward, usually forming a J-shape. The pupal skin forms
under the caterpillars skin and then the caterpillar skin splits down the back.
The pupa begins to wiggle and twist and gradually emerges from the old
caterpillar skin. At this point the old skin looks like a sock being peeled
off. With more wiggling it is gradually worked back to the point of attachment.
 |
| Cast off caterpillar skin |
|
Then the pupa performs a complex maneuver -- it grips the old skin between its
last few segments and wiggles the last segment free from the old skin. The skin
is still hooked to the silk button and the pupa is gripping the skin, hanging
from it head downward. The freed terminal segment has a hook on its end and
this hook is jabbed into the silk button and twisted around enough to anchor
the pupa. The pupa then releases the shriveled caterpillar skin. The skin
usually drops to the ground and the pupa slowly transforms into the final shape
of the chrysalis (It usually takes less than a day to complete chrysalis
formation. The butterfly will emerge a week or two later.)
Orange trail and Orange spur trail
It was getting late so we quickly turned left onto the Orange trail to see the amazing progress in Chinese Privet removal. Then we turned up the Orange spur trail to return to the Arbor, where we received our Origami Passenger Pigeon papers. Along the way we saw Ebony Spleenwort and our old friends, the Beech Blight Aphids.
We returned back to the Arbor and folded our flock at Donderos'.
 |
| Folding our flock |
|
SUMMARY OF OBSERVED SPECIES:
Common Name
|
Scientific Name
|
Shade
Garden
|
Witch hazel
|
Hamamelis virginiana
|
Pignut Hickory
|
Carya glabra
|
Mockernut Hickory
|
Carya tomentosa
|
Triangulate Orbweaver
|
Verrucosa arenata
|
Dunson
Garden
|
Northern Horsebalm
|
Collinsonia canadensis
|
Jack-in-the-Pulpit
|
Arisaema triphyllum
|
Downy skullcap
|
Scutellaria incana
|
Beautyberry
|
Callicarpa americana
|
White
trail
|
Japanese stiltgrass
|
Microstegium vimineum
|
Perilla mint or beefsteak plant
|
Peri indicutescens
|
Yellow crownbeard
|
Verbesina occidentalis
|
River oats
|
Chasmanthium latifolium
|
Smooth sumac
|
Rhus glabra
|
Purpletop grass
|
Tridens flavus cupreus
|
Upper
power line right of way
|
Flowering Spurge
|
Euphorbia corollata
|
Wild lettuce
|
Latuca spp.
|
Golden aster
|
Packera aurea
|
Mountain mint
|
Pycnanthemum incanum
|
Rabbit tobacco
|
Gnaphalium obtusifolium
|
White crownbeard
|
Verbesina virginica
|
Elephant’s Foot
|
Elephantopus tomentosus
|
Wild Sensitive Plant
|
Chamaecrista nictitans
|
Yellow star grass
|
Hypoxis hirsuta
|
Late-flowering boneset
|
Eupatorium serotinum
|
Slender ladies tresses
|
Spiranthes gracilis
|
Lower
power line right of way
|
Gulf fritillary caterpillar
|
Agraulis vanilla
|
Silver plume grass
|
Saccharum alopecuroides
|
American Pokeweed
|
Phytolacca americana
|
Camphor pluchea
|
Pluchea camphorata
|
Spotted St. Johns Wort
|
Hypericum punctatum
|
Dwarf St. Johns Wort
|
Hypericum mutilum
|
Virginia buttonweed
|
Diodia virginiana
|
Carolina anole
|
Anolis carolinensis
|
Pearl crescent butterfly
|
Phyciodes tharos
|
Tall ironweed
|
Vernonia gigantean
|
Field thistle
|
Cirsium discolor
|
Climbing Hempvine
|
Mikania scandens
|
Daisy fleabane
|
Erigeron annuus
|
Goldenrod
|
Solidago altissima
|
Gulf fritillary chrysalis
|
Agraulis vanilla
|
Small white morning glory
|
Ipomoea lacunose
|
Wingstem
|
Verbesina alternifolia
|
Leafy elephant’s foot
|
Elephantopus carolinianus
|
Ailanthus Webworm Moth
|
Atteva punctella
|
European Hornet
|
Vespa crabro
|
Yellowjacket
|
Vespula sp.
|
Orange
spur trail
|
Ebony spleenwort
|
Asplenium platyneuron
|
Beech Blight aphids
|
Grylloprociphilus imbricator
|
