The Kalu Yala Blog
February 8, 2012by Terra Filmer
Posted In: Adventures in the Tropics, Voices of Kalu Yala
As I stared at a flowering shrub, taking notes on whether its leaves were opposite or alternate, things of that sort, a hummingbird hovered a mere foot away from my face. We stared at each other for a while, I couldn’t help but think it was a little pist off I was standing between it and the sweet nectar. As it flew off I thought about all the interesting creatures of the jungle it would see, including its encounter with me! I envisioned it passing by the male Golden-collard Manakin’s snapping their wings in displays of courtship, flying over Cane Toads bigger than itself, scaring an Owl Butterfly off a tree trunk, and zipping over the millions of ant highways. The creatures here are the heart and pulse of the jungle and I feel euphoric learning about each of them one at a time. Here are a couple of the creatures I’m learning about in more detail.
While I was tromping around in the jungle I kept hearing a peculiar noise, a high pitched snap echoing through the woods. I didn’t see it for a couple days but knew from my book that it was some type of Manakin. When I finally spotted a male manakin through my binoculars, I was shocked to find it crazily hopping to and fro all the while snapping its wings loudly. The Manacus bird family is found in the neotropics and known for their interesting courtship maneuvers.
The Yellow-collard Manakin averages eleven centimeters in size and both male and female have orange legs. Males are more brilliantly colored when they are courting females, displaying a bright yellow neck with a black crown, wings, and tail, and the rest of the plumage is an olive green. Females on the other hand are entirely olive green. They can be found on lower levels of forest edge and woodland from southeast Mexico to eastern Paraguay, excluding the Antilles. Their diet mainly consists of fruit but they eat more insects during the rainy season. Per year, females produce two whitish eggs streaked with a burgundy color. The lightly constructed nests are one to three meters high on a horizontal tree fork. Incubation lasts eighteen to twenty-one days and the female cares for the young by herself due to unstable relationships.
Now it’s time for the good stuff. SNAP! Whee-yoo! SNAP! Several males gather in large courtship groups called leks. They clear their area called a court, of debris and leaf matter. Previous field observations note that they continue to use the same court for an extended amount of time. Jean Stolzmann observed “at a hundred paces once could recognize the presence of the birds by their snapping and the characteristic voice…striking its regimes against one another, Manacus produces a sort of snapping like that heard when hooking the nail of the middle finger against that of the thumb (p. 475, Chapman).” Every snap occurs when the bird hops to another branch. Watch this video to see it! Male Golden-collard Manakin displaying at his court. The males also display their yellow beards (see Figure I) and I’ve seen videos of them even flipping backwards to really impress the ladies.
They continue this courtship and nesting from the end of December to the latter part of August, including both dry and wet seasons. This makes for a total of about eight months and ” is indeed a surprisingly long period (p.487, Chapman).” I look forward to observing these courtship displays next week when we head back into the valley and taking some videos. Oh SNAP!
Daniel Medina, an amphibian researcher at the Smithsonian Institution in Panama City was shocked when I told him we found two of these giant snake, worm look alike creatures. Daniel exclaimed, “It is very rare to find them, you guys are very lucky!” Lucky indeed, these amphibians make their homes underground and are usually only seen during heavy rain fall when they emerge from the ground. In science jargon their adaption to burrowing is called fossoriality and because of this behavior, “we know relatively little about caecilians (Naish, 2008).”
Pronounced ‘say-see-lee-un’, Caecilian derived from the latin root caecus meaning blind. This is a misconception because they have small eyes, but are covered by a layer of skin and bone. Carl Linnaeus described the first species in 1758 and at first thought they were snakes hence the name Gymnophiona derived from greek words gymnos (naked) and ophis (snake). They are limbless amphibians with an elongated body over one foot long and annuli (skin folds) that resemble segments adapted for burrowing. Their bony skulls are used to push through soil and they have tough, strongly pigmented skin. The outer layer of the skin is made out of keratin, the same material that forms our hair and fingernails. It is the only tetrapod (they are descendants of vertebrate animals having four limbs) with retractable tentacles located between the eyes and nostrils. “Caecilian anatomy is surreal. Easily the weirdest features have to be the tentacles…(Naish, 2008).” These are paired sensory structures used to sense their surroundings through touch. Their relatively large mouths contain three different rows of teeth (two in the upper jaw and one in the lower). See Figure III below.
The Purple Caecilian can be found from Costa Rica to Colombia in the lowlands and premontane forest to 1400 meters and grassy areas. Not much is known about what they eat but are considered generalists, munching on earthworms and other soil-dwelling invertebrates. How they feed is a very interesting topic of debate. They facilitate what is called rotational feeding where they grab the pray item and rotate it about the long axis of their body. Why do they do this? There are two theories, one, it aids in the breaking up of oversized food and two, they can judge their prey size (Naish, Darren). Lastly, they reproduce via internal fertilization and the eggs are guarded by the female.
To wrap it up, I wanted to share with you some information I found out about a particular caecilian. The Taita African caecilian (Boulengerula taitanus) has been shown to skin feed its young! Like I mentioned earlier, their skin is made out of keratin which is rich in nutrients and apparently quite delicious but you won’t find me gnawing on them any time soon!
Chapman, Frank. The Courtship of Gould’s Manakin (Manacus vitellinus vitellinus) on Barro Colorado Island, Canal Zone. The American Museum of Natural History. Vol LXVIII, Art. VII, pp.471-525. New York. Sept. 30, 1935.
Evolutionarily Distinct and Globally Endangered (EDGE). Sagalla Caecilian (Boulengerula niedeni). <http://www.edgeofexistence.org/amphibians/species_info.php?id=548>. Web. 9, Feb. 2012.
Naish, Darren. Surreal caecilians part 1: tentacles and protusible eyes. Tetrapod Zoology. 3, Jan. 2008. <http://scienceblogs.com/tetrapodzoology/2008/01/surreal_caecilians_part_i.php>. Web. 9, Feb. 2012.