Thursday, August 29, 2013

August 29 2013 Ramble Report




We started today with an announcement: Emily and Dale will lead a walk at 9:00 AM next Tuesday, Sept. 3, 2013, at Sandy Creek Nature Center. Everyone is welcome to attend. This is the first of a monthly series of walks at the Nature Center. Emily plans to have them on the first Tuesday of each month.

We had three readings today; Hugh read an excerpt from Sean Beeching's book, I Like You But What Can You Do Can You Be A Bird, pp. 45-46.

Inland is a low forest of oaks and gums, holly and willow, the floor is mud, muddy roots and soggy leaves, it is composed of low mounds and water-filled hollows, and it is dark, even in winter, under the live oak leaves.  The history of the Ohoopee's past wanderings is here, these are the old channels and banks, oxbows and meanders, I suppose, but it is too confused and too dim to be read by me.  The two great trees here are live oak on the banks and cypress in the swamps.  Both are covered with the other great player in the coastal landscape:   Spanish moss.  Does this bromeliad cast (a) spell of lethargy over the South?  Fully developed on a big oak, ancient, shaggy, overextended. it billows in the breeze, supported not by its own efforts but by the oak, dormant as often as not.  Should some fall, so what?  There's plenty more.  Perhaps it exudes a substance, Tillandsiadol, an invisible elixir that seeps into the minds of Southerners, that makes them say, "Aw, it's alright," whether it is or not, and makes them think that living is work enough.  If this potion could be bottled I would carry it on my back and breathe it straight through a tube.

Dale read a piece about scientific names from Alpine Plants of the Northwest Wyoming to Alaska, p. 12:
If we can no longer argue for scientific names on the basis of stability, we can still make an argument for clarity. After all, even after scientific names change, there is still only one official scientific name-the new one. (Numerous common names usually remain.) You can also learn scientific names to impress people, around the barbeque or at other social gatherings. Inexplicably to some, Carla Bruni married former French president Nicolas Sarkozy. She explained that, after a courtship stroll in the Elysee Palace gardens, it struck her that "He knows all the Latin names, all these details about tulips and roses. I said to myself, 'My God, I must marry this man.'"

Terry read a wonderful poem by Janisse Ray:
Butterfly

Where does its fire go
when a monarch dies?
Does it vanish
in smoke,
or turn suddenly to rain?
Does it lay dead
against a mountainside
transforming placidly
to dirt,
which will harbor in its richness
millions of small burning ships
sailing a deep-green forest,
never to be seen?
Or does the fire seep
into the ground,
running in rivulets
toward the blazing core
of the earth,
one day to return:
a volcano spewing wings?

The subject of today's ramble was butterflies. Dale began with a few comments about books and equipment useful for learning about Georgia butterflies. 


1.   Minno, Mark C. 2013. Butterflies of North Carolina, South Carolina & Georgia: A Guide to Common and Notable Species. 

This waterproof folded pamphlet guide illustrates over 80 species of butterflies and most of their caterpillars found in North Carolina, South Carolina , and Georgia. It features color photos in a side-by-side format that makes it ideal for field use. Common and scientific names, adult size, season when they can be found, and their caterpillar host plants are listed. Tips on finding butterflies and caterpillars are given and the life cycle of the Gulf Fritillary is illustrated. Published by Quick Reference Publishing 
2.   Daniels, Jaret C. 2004. Butterflies of Georgia Field Guide.

Includes more species than the Minno fold-up guide and has larger color photos, but they are not side-by-side. Also has more information; e.g., tips on how to distinguish each species from similar forms, range maps for Georgia. Species are arranged by color, aiding identification for the beginner. An excellent little pocket size book.

3.   Brock, Jim P. and Kenn Kaufman. 2003. Butterflies of North America.

An excellent field book with all the butterflies of North America. Because of this it will be confusing for beginners to sort out the Georgia species from other similar kinds that don't live here. Has range maps, habitat information and tips on discriminating from similar species. Because its coverage is broader it lacks the detail of the Daniels book, but if you want to identify butterflies outside the southeast this is a great book.

The above are just the books I like and have found useful. There are many others available. No single book is perfect and each has its strengths and weaknesses.
Tips on equipment.
Binoculars. It is very helpful to have a pair of close-focusing binoculars to observe butterflies while they are nectaring (at rest, feeding on flowers). They should be able to focus on targets 4 to 6 feet away. Many cheaper binoculars do not have the necessary close focusing ability needed to study butterflies. Some manufacturers have produced relatively inexpensive models able to focus to a distance of 1.5 feet. Ed Wilde suggested that you can take digital photos of a butterfly and then use the zoom feature to enlarge the image so you can see small details. Thanks, Ed!
Do you need a butterfly net? Not unless you want to start a collection or want to do mark-recapture studies. You can learn a lot more about butterflies if you examine them close up and that requires learning how to catch and handle them.
The Ramble. We walked past the international garden, stopping at the bowl with the floating fern, Azolla. This fern forms a symbiotic association with cyanobacteria (formerly known as blue-green algae) that are able to fix nitrogen from the air. (Gaseous nitrogen in the air cannot be utilized by plants until it is chemically converted to a form like ammonia or nitrate that can be assimilated. Why is this important? Nitrogen is necessary to make protein. Without Azolla in rice paddys the protein content of rice would be far poorer.)

We then passed a crime scene. A large Carpenter Bee was stealing nectar from the flowers of a shrub. Instead of going into the front door, where pollinators need to enter the flower to pick up pollen, it was staying outside the flower and biting a hole in its base and sipping the nectar without getting any pollen.
There was a planting of Lantana in the shade and no butterflies present.

Someone asked why. Butterflies are cold-blooded creatures, unable to maintain a high body temperature through their own metabolism. In addition, they have a large surface area in relations to their mass. This means they lose heat rapidly in the shade and gain it quickly in the sun. In a shaded area they can still fly if their body temperature is above a critical value, but they may not be able to do so efficiently or as swiftly because they have cooled. It is better to avoid the shade and keep their body temperature near the optimum value to be able to flee any predators that might threaten them.

We stopped at a Bee condominium to see how it was constructed. Many of the different species of native bees are solitary -- a single female builds a nest for her offspring only and leaves them alone once it is provisioned. These bees are important pollinators for native wildflowers and need to be encouraged by providing ready-made housing for their nests. The Condo we examined had a number of pieces of scrap wood into which many holes were drilled. The bees will use the holes to build their individual nests, supplying them with a paste of pollen and nectar. Avis sent me a link to a website that shows how to build a fancier insect hotel.

Butterflies netted and shown:
·        Clouded Skipper
·        Pipevine Swallowtail
·        Tiger Swallowtail (female, dark form)
·        Tiger Swallowtail (male, yellow)
·        Black Swallowtail (female)
·        Gulf Fritillary
Butterflies seen, but not netted:
·        Silver-spotted Skipper
·        Fiery Skipper
·        Hairstreak sp.
·        Giant Swallowtail

The Pipevine Swallowtail is interesting for two reasons: 1) The color of the upperside of the hind wings is structural, not pigmented. From one angle it looks metallic blue and from another, metallic green; 2) It is distasteful and serves as a model for a mimicry complex that involves four other butterfly species.

The Pipevine mimics are the female Black Swallowtail, the dark form female Tiger Swallowtail, the Spicebush Swallowtail (not seen today), and the Red-spotted Purple butterfly (also not seen today). All these species are dark and have either blue or green coloration on the upper surface of their hind wings. The resemblance to the Pipevine Swallowtail is not exact, but it is similar enough to be effective.

The Gulf Fritillary is thought by some to mimic the Monarch, at least on its upper wing surface.

Sue asked why only the female Tiger Swallowtails are melanistic (dark in color, due to the same pigment, melanin, that produces dark hair in humans). The dark coloration is caused by a sex-linked gene, but there is a catch. In butterflies (and birds, too) the female is the heterogametic sex -- meaning that they have two different sex chromosomes, dubbed Z and W. Male butterflies have two Z sex chromosomes. The gene for dark wing coloration is carried on the W chromosome so it can never appear in the males.

The dark females are the commonest female color; sometimes a black and yellow female is found in Georgia, but they are uncommon. Outside the geographical area where Pipevine Swallowtails are found the dark form becomes uncommon and the black & yellow tiger pattern is typical of both sexes. In other words, the advantage of the mimetic form is lost when the model is absent.

It was getting hot in the sun and many were seeking shade to cool off, so we decided to give the butterflies a break and adjourned to Donderos' as is our custom.

No comments:

Post a Comment

Post a comment