Tuesday, May 19, 2009

As the Swamp Turns

It has been a VERY busy few days at the Audubon Center at Francis Beidler Forest! Fine weather on Saturday drew a constant stream of visitors to the old-growth swamp. Those exiting the boardwalk reported seeing does and fawns (being chased by hunting dogs); Barred Owls (Strix varia) feeding crayfish to their young; various snakes, including a Greenish Rat Snake (Elaphe obsoleta x quadrivittata) at the lake observation tower with a noticeable bludge in its middle; Prothonotary Warblers (Protonotaria citrea) flying with insects in their bills or singing; Yellow-crowned Night Herons (Nyctanassa violacea) diminishing the crayfish populations; and 1000-year-old trees doing what they've been doing for...well, 1000 years!

Saturday evening, the air temperature dropped along with the humidity and set off a performance by the swamp's finest. Prothonotary Warblers sang and flashed their fine, yellow feathers during bold displays in front of the visiting National Audubon Society Board of Directors. Barred Owls called to each other in an ever-rising cacophony. Back under the tents, guests dined on grilled corn, steammed vegetables, fried chicken and barbecued ribs as frogs of every species began to sing dimming the light.

Sunday's cold front and associated rain (2.70") arrived late in the day, but the effects were felt into Monday morning. A science education video crew with students from the local Rollings Middle School of the Arts arrived at 7:30 am for shooting in the largest-remaining, old-growth, cypress-tupelo swamp. Although the overcast skies provided outstanding lighting, the damp, cool air made it difficult for the talent to say their lines without chattering! Even dragonflies and damselflies found it too cold to get airborne, which made for some spectacular up-close, student-insect filming. We also saw Prothonotary Warblers feeding chicks; Barred Owls hunting crayfish; crayfish crawling scared and challenging us with their big, nasty claws; Eastern Cottonmouths (Agkistrodon piscivorus piscivorus); Yellow-crowned Night Herons; Eastern Mud Turtles (Kinosternon subrubrum subrubrum); and a fawn parked on high ground near the boardwalk. The crew and talent filmed scenes on the boardwalk, in the swamp, and finally in a canoe on Mallard Lake. A long day, but how can one complain when "working" some place like no other place on Earth!

As Jeff came off the boardwalk yesterday, he mentioned finding a Brown-headed Cowbird (Molothrus ater) chick in a Prothonotary Warbler nest near #138. Female Brown-headed Cowbirds lay their eggs in other bird species' nests and may even remove some of the other birds' eggs. When the cowbird chick hatches, often before the host species eggs hatch, it will have first crack at the feeding parents' attention. Its larger size will help the cowbird chick maintain feeding dominance. Additionally, the cowbird chick will eject eggs from the nest by leveraging an egg onto its back and hoisting it over the nest's edge. As this Prothonotary Warbler nest is deep in a cypress knee, the cowbird chick may not have been able to eject the eggs. All four hatched, though one Prothonotary Chick was significantly smaller than its siblings.

Jeff was able to band the Prothonotary Warbler chicks before they fledged. Today, Brad, a former seasonal naturalist (season 1 & 2), was able to get images of one Prothonotary Warbler chick leaving the nest. Its short flight ended in the water, but Prothonotary Warbler chicks have the ability to "paddle" through the water with their wings. The chick made it to a tree and up to a low branch. Shortly after the Prothonotary Warbler chick exited the nest, the cowbird chick followed. After sitting atop the cypress knee containing the nest, the cowbird chick made a short flight that also ended in a water landing. Cowbird chicks, however, do not possess an innate ability to move through the water. The cowbird chick floundered and was unable to move out of the cold water (air temperature was in the 50sF) even though is was at the base of a tupelo or cypress buttress. Hypothermia will likely end its short life and a passing cottonmouth or scavengers like turtles will clean up the remains. The parasitic female cowbird wasn't around to see the poor choice she made in selecting a host species that nests over water, so she wasn't able to learn from her mistake.

Death also came during the cold, wet night for the fawn along the boardwalk. The weekend-long harassment by the dogs may have kept the doe from caring for her fawn or the fawn may have been destined to die from disease or genetic defect. No matter, its dead body attracted insects (mainly flies and beetles) within minutes. Eggs laid on the carcass will devour everything but bone and hair within days. Other animals will gnaw on the bones for calcium and other minerals, so any evidence of the fawn's existence will be gone within weeks.

Life goes on and death plays its part in continuing life. Tomorrow, the 6th graders from the Charleston County School of the Arts will get their chance to redeem their raincheck and experience the life of the old-growth swamp! Let's hope for warmer, drier weather!

Images by Mark Musselman

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