The San Marcos River

The San Marcos River is a spring-fed river located between Austin, Texas and San Antonio, Texas. The San Marcos River is only 75 miles long and eventually joins with the Guadalupe River. At the headwaters the river is crystal clear, thanks to the headwaters being spring fed. It is the crown jewel of Texas State University in San Marcos, Texas and is a popular site for tubing but few know about the interesting animals that live in the river. In fact, it’s considered one of the most diverse aquatic habitats in the southwestern United States.

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It’s home to an endemic species of river grass, called Texas Wild Rice (Zizania texana). Other inhabitants of the river include freshwater mussels (including the Golden Orb (Quadrula aurea)), turtles, prawns, Guadalupe bass (Micropterus treculii), and suckermouth catfish (Hypostomus plecostomus). The later as nonnatives, that were accidentally released into the river by humans. The river is also home to the endangered foundation darter (Etheostoma fonticola). It formerly was home to the endangered.  San Marcos Gambusia (Gambusia georgei) but the species hasn’t been seen in recent years. There are a few other endangered species you can read about here.

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A gar at the Meadows Center boardwalk, captured by Lauren Schramm

The headwaters of the river come from Spring Lake in San Marcos, which was originally created by a dam. You can watch the lake turn into the river from the patio at Saltgrass Steak house. The lake is fed by the Edwards Aquifer. You can actually dive in the lake, or take a glass-bottom boat  (at the Meadows Center) and see the aquifer producing water. If you park in this area and access the river via the culvert by the Freeman Aquatic Center the island is actually a great source of arrowheads after a large rain event.

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A bed of Texas Wild Rice

The Meadows Center is located where a former amusement park was located called Aquarena Springs. The park was home to “real” mermaids and a diving pig. Today you can still find pony beads from the former clown act and bottle caps from an act the mermaids did in which they drank coke underwater. Technically the beads and caps are artifacts so you are not supposed to take them but that doesn’t stop people.

 

Frog Taxonomy (with a focus on Georgia frogs)

Georgia currently has 30 native frog species and two introduced frog species that fall into six different families.

The most distinct of these families is Bufonidae or the true toads. All toads will be found in this family. All toads are frogs but not all frogs are toads. Toads are a specialized group of frogs who typically have warty dry skin, are short and stubby, and large glands on the sides of their heads that kind of look like shoulder pads and are called parotoid glands.  Toads can actually aim these glands at predators. The glands release a toxin, called bufo. That’s why it’s common to see toads hopping around during the day. The eggs are typically laid in long strands. Toads also have no teeth. Worldwide there are 604 species in this family.  In Georgia we have 4 species; American Toad (Anaxyrus americanus), Fowler’s Toad (Anasyrus fowleri), the Oak Toad (Anaxyrus quercicus), and the Southern Toad (Anaxyrus terrestris). In the Metro Atlanta area, it’s common to hear both American and Fowler’s toads calling. The Ameican toad sounds like a long musically thrill that lasts between 6 and 30 seconds. The Fowler’s Toad sounds like a harsh thrill, kind of like a nasally WAAAHHHH.

 

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Red-spotted toad (Anaxyrus punctatus, formerly Bufo punctatus), captured by Lauren Schramm

 

The largest family of frogs in Georgia is Hylidae or the tree frogs, chorus frogs, and cricket frogs. Worldwide the family has 710 species. They all shared a claw-shaped finger which is found at the end of their toe pad. The toe pads function not like suction cups, but via wet adhesion, similar to 2 pieces of wet glass sticking together. In Georgia we have the Northern Cricket Frog (Acris crepitans), Southern Cricket Frog (Acris gryllus), Bird-voiced Treefrog (Hyla avivoca), Cope’s Gray Treefrog (Hyla chrysoscelis), Green Treefrog (Hyla cinerea), Pine Woods Treefrog (Hyla femoralis), Barking Treefrog (Hyla gratiosa), Squirrel Treefrog (Hyla squirella), Cuban Treefrog (Osteopilis septentrionalis), Mountian Chorus Frog (Pseudacris brachyphona), BRimley’s Chorus Frog (Pseudacris brimleyi), Spring Pepper (Pseudacris cruicifer), Upland Chorus Frog (Pseudacris feriarum), Southern Chorus Frog (Pseudacris nigrita), Little Grass Frog (Pseudacris ocularis), and finally the Ornate Chorus Frog (Pseudacris ornata). The Cuban Treefrog is actually an invasive species that is twice as large as our native treefrogs and it consumes them! It’s really hard to find because it’s a treefrog and so there is not much we can do about it’s invasion. The upland chorus frog (sounds like running your finger along a comb), spring pepper (sounds like bird-like peeps), Cope’s gray treefrog (harsh, high pitched trill), green treefrog (nasally and duck-like), bird-voiced treefrog (like a bird call whit-whit-whit), squirrel treefrog (harsh repetitive, squirrel-like call), and northern cricket frog (sounds like two marbles being tapped together) can all be found in the Metro Atlanta area.

 

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Cope’s Grey Treefrog, captured by Lauren Schramm

 

The family Ranidae contains true frogs who have smooth and wet skin. Worldwide they have a large range. Generally, they are aquatic or live close to water. This family is probably what comes to mind when most people think of frogs. In Georgia you can find Gopher Frogs (Lithobates capito), Bullfrogs (Lithobates catesbeinanus), Green Frogs (Lithobates clamitans), Pig Frogs (Lithobates grylio), River Frogs (Lithobates heckscheri), Pickeral Frogs (Lithobates palustris), SOuthern Leopard Frogs (Lithobates sphenocephalus), Wood Frogs (Lithobates sylvaticus), and Carpenter Frogs (Lithobates virgatipes). Bullfrogs, green frogs, pickerel frogs, and Southern leopard frogs all have calls that can be heard in the metro Atlanta area. Respectively the calls sound like a repeated jug-o-ruummmm, like a banjo pluckling, a snoring person, and the sound of squeezing a balloon.

 

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Pickeral Frog, captured by Lauren Schramm

 

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The Georgia coast is key to shorebird conservation

A few months ago I attended the monthly Atlanta Aubdon Society meeting which was on the role of the Georgia coast and shorebird conservation. The talk was given by Brad Winn from Management center for conservation, Tim Keyes from the GeorgiaDepartment of Natural Resources and Abby Sterling from the University of Georgia.

Abby started the talk by giving a general overview of the habitat on the coast and the life history of shorebirds with a particular focus on Oystercatcher and Wilson’s plovers, the birds she did her doctoral studies on. The beaches on the Georgia coast are dynamic habitats as they do not have engineering typically found on beaches that hinder the natural movement of sand. These beaches are found on a chain of barrier islands that are formed from sediments that drain from the whole state. Shorebirds (at least these two species) lay their eggs in scrapes in the sand or sometimes in a horseshoe crab shells or flowers. The two species did not have an overlap of their nesting habitat which is important for conservation. The nests are typically hard to find and Abby said she had to follow the tracks of birds to find the nets. She monitored nests until they were successful or unsuccessful. This took about 28 days for Wilsons plovers. The chicks get fed by the parents. Abby would catch and band the birds and give the chicks a unique color band combination of ease of field identification.

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Wilson’s Plover

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Mist-netting and passerine bird banding

A key component to bird studies is bird banding, in which each bird has a band with a unique number placed on the bird. Sometimes, larger birds will also have colored bands placed on them which allows the individual to be recognized without recapturing them.  This allows changes in populations, dispersal, survival and migratory movements to be studied. Banding birds also gives insight into natural history, particularly, on body conditions during taxing periods of their life cycle like breeding and migration. As part of my undergraduate studies, my class did an activity on bird banding at my professor’s house. Since he is a master bander we were able to sample birds in mist nets.

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The study was conducted on November 21st, 2013 at Dr. Beaudry’s house in Alfred, New York from 9:15 am to 11:00 am. Mist nets (which are large thin nets that birds can’t see in flight and therefore fly into and get caught) were set up near feeders and the collected birds had data recorded about their body and they were banded and released. Data collected included age, sex, wing length, weight, and furcular fat score.

In total there were 16 birds captured from 4 species; Black-capped Chickadee (Poecile atricapillus), White-breasted Nuthatch (Sitta carolinensis), American Goldfinch (Carduelis tristis), and Purple Finch (Haemorhous purpureus). The details of each individual are recorded below (table 1).

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One of the largest unicellular organims: the Sea Pearl

When beachcombing in the Bahamas I discovered a number of mostly round, about quarter size, water filled, and plastic-like outside objects. I brought one of the odd objects to my professor and he informed me that they were a kind of algae (Ventricaria ventricosa) known commonly as sea pearls (also called bubble algae and sailor’s eyeballs). After recovering from the guilt of poping a whole bunch of sea pearls, thinking they were some kind of trash, I researched more about them. And in case you were wondering, they poped kind of like a water balloon. They were filled with water and not much else. Their cell wall was very plastic like and rubbery. Sadly, they did not resemble a large version of the classic plant cell you learn about in biology class.

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Blog goal

Hello!

My name is Lauren Schramm and ever since I can remember I have learned every bit about the natural world that I could. I graduated from college with a degree in biology and environmental studies. After living in Vermont, New York, and Texas I find myself in Georgia.

DSCN6110.JPGI am trying to learn as much about the natural world as possible. This blog will serve as a place for me to document my learning. My interests are very varied so likely this blog will be as well but it will always be connected to the natural world and educational.