Monday, February 15, 2010

ROADTRIP: The Galapagos Islands, Santa Cruz edition

Over 2,600 miles away from North Carolina’s Triangle and nearly 700 miles away from the closest continent, the Galapagos Islands rise like uncut gems from the cerulean sea far to the west of Ecuador’s coastline. At first glance, each of the volcanic archipelago’s fifteen major islands seem rough and rocky, some lightly painted with a thin crust of vegetation. Upon closer inspection, the rugged, lapidarian landscape, largely isolated from the evolutionary pressures of the mainland, reveals radiant ecological splendor. The crown jewels of the Galapagos include ruby-red and sapphire-hued birdlife, preternaturally tame reptiles and mammals, and other-worldly vistas.

Situated in the center of the Pacific island cluster, Santa Cruz or Indefatigable Island, is the second largest landmass in the archipelago. Santa Cruz, named after the Holy Cross by the Spanish and for the HMS Indefatigable by the British, currently houses over 4,000 permanent human residents, making it the most populated of the Galapagos Islands. The island is also home to the Charles Darwin Research Station, best known for its research on the giant Galapagos tortoises.

The Galapagos giant tortoise, the world’s largest living tortoise, once consisted of up to fifteen different subspecies, eleven of which exist today. Each subspecies is adapted to the conditions of a particular island and the different volcanic slopes of that island. For example, the Hood Island subspecies (Geochelone nigra hoodensis), with its long neck and downward sloped carapace, is limited to scrubby Espanola (aka. Hood Island), while the Volcan Wolf subspecies (G. n. becki), looking like an old grandmother sunk low in her shawl, is limited to the northern and western slopes of the Wolf Volcano on lush Isabella Island. Nearly all of the giant tortoises face severe population pressure resulting from hunting that came with whaling vessels and the introduction of non-native species, like goats, which wreak havoc with tortoise food supplies by reducing areas to desert.


Indefatigable Island tortoises (Geochelone nigra porteri), Santa Cruz Island, Galapagos Islands, Ecuador, March 4, 2004 (© Nicolette L. Cagle)



In March 2004, my family (parents and husband) and I had the opportunity to meet the amazing tortoise endemic to Santa Cruz, the Indefatigable Island tortoise (Geochelone nigra porteri). This sub-species has a near perfectly domed shell and dark, deep soulful eyes. Walking up to one of these gigantic reptiles felt like sneak-peaking into pre-history. With slow, deliberate steps I moved closer and closer to one of the tortoises, whose attention was focused on steadily chomping viridescent grass shoots, a favorite food. My eyes perused the ancient anatomy: black, half-dollar sized scales covering heavy limbs; glistening, tar-like scutes of its massive shell; and a massive, brown-black beak closed over green grass hanging out like half eaten strands of spaghetti. The chelonian relic lifted his head, regarded me warily and turned slowly away.

A visit to Santa Cruz yields more than intimate encounters with antediluvian turtles. As you explore the misty island, the geologic remnants of Santa Cruz’s volcanic origins often steal the scene. Walking to the highest part of Santa Cruz, visitors find Los Gemelos, seemingly bottomless twin craters formed by the collapse of a magma chamber. The holes, nearly 100 feet deep, reveal the striated layers of the island’s dormant volcano. An additional geologic wonder is the 800-yard long Tunnel Endless of Love, one of Santa Cruz’s several lava tubes or large tunnels formed by ancient magma flows. If walking through tunnels of cooled primordial magma doesn’t dizzy your brain with thoughts about Earth’s creation, the of the planet and man’s minuteness, you can at least enjoy the some of the critters that have adapted to the primeval conditions of the volcanic archipelago, e.g., lava lizards, lava herons and lava gulls, to name a just a few.


Collapsed magma chamber, Santa Cruz Island, Galapagos Islands, Ecuador, March 4, 2004 (© Nicolette L. Cagle)


Lava tunnel, Santa Cruz Island, Galapagos Islands, Ecuador, March 4, 2004 (© Nicolette L. Cagle)


Santa Cruz is just the beginning. Come back next month for "The Galapagos Islands, Rabida edition" for an introduction to the sea lions and iguanas of the Archipi├ęlago de Col├│n.

Monday, February 8, 2010

Turtles Times at Goose Creek State Park (Beaufort County, North Carolina)

Here is all you really need to know: It was May 2007. We arrived at Goose Creek State Park. And “turtle time” began.

My trusty companion (my husband, Mark) and I pulled up to the primitive campground in our reliable blue Jeep. I jumped out of the passenger side before Mark even turned off the ignition, my feet landing on coarse tan sand overlain with pine needles. Finally, I groaned. The trip from Durham had seemed endless. As each moment of our two and a half hour drive ticked by, I had painfully envisioned the herps and warblers we were missing at the park.

Fate was mocking me that day. As I deeply inhaled the briny air, calming my frazzled nerves, and turned to survey the tall longleaf and loblolly pines sprayed with Spanish moss, movement caught my eye. A dullish-brown object resembling an upside-down dinner plate seemed to scuttle away from me. Turtle! Mark, a turtle! I yelled. I rushed ahead, catching up with a big female yellow-bellied slider who was leaving a strange trail of half-moon imprints in the sandy debris as her webbed feet propelled her along the forest floor. This sizeable female, with the faded yellow mask that distinguishes her species from North Carolina’s nineteen other aquatic turtles, was moving away from Goose Creek, a former refuge for pirates like Blackbeard and Stede Bonnet, which runs into North Carolina’s Pamlico Sound .

Mark put it all together before I did. She’s going off to nest, he opined with the confidence of a lifelong naturalist. And he was probably right: yellow-bellied sliders nest in May and early June in the Carolinas, and usually find a mesic spot away from water in which to lay eight to twelve creamy oblong eggs. Tiny, carnivorous sliders will hatch after about two months, as long as the eggs evade the detection of pilfering raccoons, and eventually those juvenile turtles mature into the omnivorous, sun-loving adults of floating logs that we all know and love.

I snapped some photos of our mama-to-be, and then looked at Mark meaningfully, We have to start walking, I said sternly, terrified that we might miss one of Goose Lake State Park’s natural wonders. We had a lot of ground to cover: Goose Lake State Park houses six hiking trails, ranging from the 0.4 mile Live Oak Trail that goes past an old cemetery and skirts Pamlico Sound to the 1.9 mile Goose Creek Trail that descends through Cypress swamp. The six trails are interconnected, and I wanted to explore them all.



Yellow-bellied slider, Goose Creek State Park, 15 May 2007 (© Nicolette L. Cagle)


Our first goal was to investigate Flatty Creek, a small and mysterious stream that feed the Pamlico River and terminates in a sedge and sawgrass marsh perfect for nesting herons, egrets and rails. First we walked through pine woods that seemed to get swampier and swampier with every step. As we got closer to the creek, we heard the buzzy trill of the northern parula, a tiny gray warbler with a yellow breast known to loiter around wet woods, gleaning insects from the foliage. We stepped onto a little footbridge and spied a good-sized red-bellied water snake. My husband looked back at me with a satisfied smile, before continuing. A minute later, we came across another footbridge. I peered into the brown-black water, intrigued by bright orange-yellow flecks in the shallow pool. Mark, I hissed sotto voce. He hadn’t heard me. He was walking away. Quickly, barely thinking, I dropped to my knees and lunged forward, plunging my hand into the warm tea-colored swamp. My wet hand emerged triumphant. I had captured a spotted turtle.

Mark! Mark! I hollered, turtle in hand. He hurried back to me, perplexed that I was still at the bridge until he saw my yellow-spotted prize. Oh wow, he said, his voice hushed with reverence, a spotted turtle. For both of us, this spotted turtle was a first, a species to be added to our “life list” of herps. Moreover, spotted turtles are not particularly common. Limited to the Great Lakes and the coast of the eastern United States, these denizens of wet meadows and swamps are listed as threatened by the World Conservation Union, and remain defenseless against land development and habitat drainage. After a few minutes, we carefully returned the teeny, four inch turtle to its muddy home and continued to explore the park.

Our exploration led us to scenic flat marsh vistas, took us past cypress swamps and beneath the secret homes of warblers and wrens nestled in the tall pines. We imagined ourselves running into bobcats and bears, Goose Creek natives still found in the area today. Late in the afternoon, after hours of birding and tree identification, one more surprise was waiting for us. On the trail back to the primitive camp, nestled in pine needles, we found an eastern box turtle. Bright eyed and vividly colored with yellow stripes crisscrossing its brown carapace, the familiar eastern box turtle brought a whimsical smile to our faces and left us with warm memories of “turtle times” at Goose Creek State Park.


Eastern box turtle, Goose Creek State Park, 15 May 2007 (© Nicolette L. Cagle)

Monday, February 1, 2010

Great Expectations: February in the Piedmont

Birds.− In the heart of winter in North Carolina, not many changes are happening in the bird world. By the end of the month, purple martins and tree swallows will begin to reappear. Barred owls start hooting their mating calls this month. Also, woodcocks begin their elaborate courtships in February. It is worth braving the cold this month to watch male woodcocks spiral skyward and fall rapidly back down to earth making a distinct “peenting” call in hopes of attracting a mate.

Ever wonder what birds eat this time of year? Our year round residents have a remarkably flexible diet that adapts to changing food supplies. For example, eastern bluebirds typically feed on insects and other invertebrates during the warmer months, but depend on small fruits and berries to satisfy their hunger in the winter months. Some birds, including crows, jays, nuthatches and titmice, will even feast on carrion if needed. Carolina chickadees are particularly flexible. During the summer, 80-90% of their diet is made up of small insects and spiders. In winter, approximately 50% of the Carolina chickadee’s diet is composed of seeds and fruits, including those of poison ivy, Virginia creeper, pines, and eastern redbuds, with the remainder being made up of their typical warm-weather cuisine.

Butterflies.− Butterfly enthusiasts can rejoice: many of our over-wintering species will re-emerge this month with the slightly warmer weather. Near forested habitats, one might expect to see question marks, eastern commas and mourning cloaks. In open habitats (e.g., fields and roadsides), expect to find American ladies, late sulphurs, orange sulphurs, clouded sulphurs and cabbage whites, a commonly seen species that was introduced from Europe.

Reptiles & Amphibians.− This month, expect to continue hearing southeastern chorus frogs and spring peepers. You might also catch the sharp, repetitive clinking of a northern cricket frog, the musical trill of an American toad, the low-pitched croak of the pickerel frog or the sheep-like bleat of the eastern spadefoot. Also, continue to look for breeding salamanders.

In Bloom this Month.− February is a great month to eradicate any non-native, invasive plant species growing on your property, many of which are easy to identify even in the middle of winter. In the southeastern United States, most invasive species arrived from Europe or southeast Asia (areas that share the deciduous forest biome). These species have arrived accidentally (e.g., Microstegium, an invasive grass, arrived as packing material), as well as intentionally (e.g., the princess tree was introduced by horticulturalists.) Once an invasive species gets a foot-hold, it can alter the vegetation structure of a community, change food resources for wildlife, and even affect ecosystem-level processes such as sedimentation, erosion, soil chemistry and fire regimes.

Important Terms:
Exotic species – a non-native plant that will grow, but not spread in a given ecosystem
Invasive species – a non-native species that will spread and cause harm in a given ecosystem
Native species – a species that historically occurred in a given ecosystem
Noxious weed – any plant whose presence is detrimental to crops or desirable plants, livestock, land, other property or is injurious to public health (note: can be native)

Notable invasive plant species in our area:
Chinese privet (Ligustrum sinense)
Chinese wisteria (Wisteria sinensis)
Common reed (Phragmites australis)
English ivy (Hedera helix)
Hydrilla (Hydrilla verticillata)
Japanese stilt grass (Microstegium vimineum)
Mimosa (Albizia julibrissin)
Multiflora rose (Rosa multiflora)
Oriental bittersweet (Celastrus orbiculatus)
Princesstree (Paulownia tomentosa)
Russian olive (Elaeagnus angustifolia)
Sericea lespedeza (Lespedeza cuneata)
Tree-of-heaven (Ailanthus altissima)

Wildlife Profile.− This month’s wildlife profile is the MOURNING CLOAK BUTTERFLY (Nymphalis antiopa). The mourning cloak is one of the first butterflies to re-emerge in North Carolina. This species is the longest lived in the United States, surviving up to 11 months. The adults are dormant in winter, and then re-emerge, wings imperfect and worn, during the first warm days of late winter and early spring. This time of year, males are quite bold, bravely chasing birds out of their 300 m2 territories. In early spring, males and females perform a beautiful mating dance, spiraling upward through the air. The females will then lay clusters of eggs on their favorite food plants, black willows, as well as other willow species, elms, birches and hackberries. Although the females die shortly thereafter, caterpillars will emerge from the eggs in April. After three weeks, this brood will have pupated and emerged as fresh, young mourning cloaks. The adult mourning cloaks are usually found in woodlands, where they feed on tree sap (especially oak sap), rotting fruit and occasionally nectar, building up stores for the winter.

Did you know?
• Mourning cloak butterflies spend the winter frozen in “cryo-preservation.”
• They can live up to 11 months in the wild.
• Their common name refers to their resemblance to the traditional cloak one would where while in mourning.
• Caterpillars live communally in a web and feed on young leaves.

Identification: The mourning cloak has brown wings with small blue spots bordering a yellow edge. It reaches 2 ¼ to 4 inches in length.

References:
Cook, D. 2001. The Piedmont Almanac. Chapel Hill, NC: Mystic Crow Publishing.

Daniels, J. C. 2003. Butterflies of the Carolinas. Cambridge, MN: Adventure Publications, Inc.

LeGrand, H. E. Jr., and Howard, T. E. Jr. 2009. Notes on the Butterflies of North Carolina, 19th Approximation. Available at http://149.168.1.196/nbnc/

Read, M. 2005. Secret lives of common birds: Enjoying bird behavior though the seasons. New York: Houghton Mifflin.

http://en.wikipedia.org/wiki/Nymphalis_antiopa