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Frog Communication – Study Shows Frogs go far Beyond Croaking

Rana adenopleuraHello, Frank Indiviglio here.  A recent study has challenged what we know, or thought we knew, about frog communication.  Researchers were astonished to discover that the calls of male Emei Music Frogs, (Babina daunchina) inform females of such details as the length and width of the singer’s burrow. 

Construction Skills Needed

Named for the males’ banjo-like calls (they really do sound like banjos, please check video below), the Emei Music Frog is native to marshy habitats in central and southwestern China.  Females deposit their eggs in burrows constructed by the males, and the tadpoles develop there as well.  The ability to construct a safe burrow is, therefore, an important consideration when females go “mate shopping”.  You can see photos of the unique nests and egg masses of a related species, Japan’s Ryuku Brown Frog, here. Read More »

Amphibian News – Bacteria Offers Immunity against Deadly Chytrid Fungus

Mountain Yellow-legged FrogHello, Frank Indiviglio here.  A bacterium that naturally occurs on the skin of certain frogs and salamanders has been shown to protect these animals from infection by a deadly Chytrid fungus infection.  Chytrid fungus, known as Batrachochytrium dendrobatidis, has been very much in the news since its discovery in 1999.  It is believed to have caused the extinction of up to 200 amphibian species, and is still spreading in many countries. Read More »

Current Field Research – Amphibian Behavior and Natural History

Strawberry Poison FrogHello, Frank Indiviglio here.  Many interesting, current amphibian and reptile field research reports are published in professional journals such as Copeia, Herpetologica and Herpetological Review, and are not available on the internet.  Unfortunately, such journals are usually quite expensive (if well-worth the price).  From time to time I’ll provide summaries of some of the fascinating articles that I come across.  Today’s report covers Spring, 2020 publications: Clouded Salamanders, Red-Eyed Treefrogs, Green Frogs and Strawberry Poison Frogs.

Clouded Salamander, Aneides ferrus

Although known to climb trees, the Clouded Salamander is most often found (and studied) below fallen logs.  Researchers in southwestern Oregon were, therefore, surprised to find a pair of these salamanders in a tree cavity (Douglas Fir) 240 feet above the ground.  Red Tree Voles (small arboreal rodents) were also using the site for food storage. 

It is not known if water contained within tree cavities might provide a breeding site for Clouded Salamanders.

Red-Eyed Treefrog, Agalychnis callidryas

Researchers in Costa Rica reported the first known example of a spider feeding upon amphibian eggs.  A Rusty Wandering Spider (Cupiennius getazi) was photographed while consuming Red-Eyed Treefrog eggs, which had been deposited on a leaf overhanging a small pond.  Interestingly, the spider appeared to defend its food source. 

The eggs did not spontaneously hatch when disturbed by the spider, as they do when attacked by wasps and snakes.
Red-eyed Tree Frog

Strawberry Poison Frog, Oophaga pumilio

Although diurnal activity is the rule for Dendrobatids (Poison Frogs), male Strawberry Poison Frogs were observed calling and engaging in territorial battles after dark (Costa Rica)…perhaps its time to install night-viewing lights on our Poison Frog terrariums!

Green Frog, Rana clamitans

Long known for occasionally producing blue-colored Green Frogs, a stream in upstate NY has now yielded a brilliant yellow specimen.  The frog also sported a black blotch on its back, green above the eyes, and greenish-brown legs – quite a sight!

Further Reading

A video of a treefrog eggs hatching while being attacked by a snake, along with fascinating info and photos, is posted on the Warkentin Lab website.

Please write in with your questions and comments. 

 

Thanks, until next time,

Frank Indiviglio

 

A Bird-Eating Frog is Discovered in Thailand – Research Update

Hello, Frank Indiviglio here.  In 1705, a painting of a Pink-toed Tarantula consuming a hummingbird, published in Maria S. Merian’s book on the insects of Suriname, aroused so much attention (and horror!) that all New World tarantulas are commonly termed “bird-eating spiders” to this day.  It seems now that amphibian fanciers have their own dramatic bird-eater – Limnonectes megastomias, an aquatic frog recently described from 3 locations in Thailand. 

An Aquatic Ambush Predator

Limnonectes kuhliiThe newly discovered frog is largely aquatic, and apparently catches birds that come to the water’s edge to drink – quite a unique feeding strategy for a frog (I once saw a surprising film of African Side-necked Turtles catching doves in this manner). 

It is assisted in hunting by large (to 2 inch) “fangs” and a head that is disproportionately large for the body.  The fangs are not true teeth but rather extensions of the jawbone, known as odontoid processes.  The African Bullfrog and the South American Horned Frogs, known also for consuming vertebrates (and biting the hand that feeds them!), also sport odontoid processes.  Insects and other frogs have also been recorded as prey.

Same Bodies, Larger Heads – Sexual Dimorphism

Interestingly, the heads and “teeth” of male Bird-eating Frogs grow much larger than those of females, despite similar body sizes.  In certain other creatures (i.e. Barbour’s Map Turtles) this strategy allows the sexes to consume different diets and, it is theorized, avoid competition.  Researchers also believe that the enlarged teeth are used in combat, as many males carry scars.

So Much to Discover

There are over 50 species classified in the genus Limnonectes- the new “bird-eater” appears most closely related to the Kuhl’s or Large-Headed Frog, L. Kuhlii, but little is known of its natural history (the photo attached is of a Kuhl’s frog).  

This new species was first observed at the Sakaerat Environmental Research Station, an area that has been extensively studied for 40 years.  The fact that such a large and unique frog was able to remain undiscovered in this area illustrates the untold opportunities open to those who wish to get out and look around in just about any habitat – recently a new centipede was discovered in NYC’s Central Park!

Further Reading

Another toothed amphibian behemoth, the African Bullfrog, also takes quite large prey…to read about a most unusual frog meal, please see my article An Appetite for Cobras.

Please write in with your questions and comments. 

Thanks, until next time,

Frank Indiviglio

Limnonectes kuhlii image referenced from wikipedia and originally posted by W. Djatmiko

Research Notes – Hourglass Treefrogs (Dendropsophus ebraccatum) can choose either land or water as egg deposition sites

Frogs are full of surprises when it comes to reproduction – there are species that incubate eggs below the skin of their backs and in the vocal sacs, while others carry them wrapped about their rear legs or construct foam nests on land.  But in May of this year Boston University biologists working in Panama uncovered what may well be the oddest reproductive strategy of all – a frog that actively chooses to lay its eggs on either land or in water, depending upon the threats presented by each habitat.  To date this is the only example of an egg that can hatch in either environment, and these frogs are the only vertebrates known to show such reproductive flexibility.

When breeding near shaded ponds, hourglass frogs lay their eggs on tree leaves overhanging the water (the tadpoles drop into the water upon hatching), thus avoiding fish and other aquatic predators.  However, when utilizing ponds exposed to the sun, the majority of the frogs lay their eggs directly in the water, lest they dry out before hatching.

The “decision” is not governed genetically, because the same female frog will choose different egg laying sites when placed in a shaded or un-shaded pond.

Amphibians were the first group of vertebrates to evolve some independence from water.  Biologists are now studying the hourglass frog to determine if its unique egg-laying flexibility might shed light on the evolution of terrestrial amphibian eggs.

Keep watching and studying your animals – amazing new discoveries are a real possibility.  Please write in with your questions and observations.  Thanks, until next time, Frank.

You can read more about the hourglass treefrog and its relatives at:
http://research.amnh.org/herpetology/amphibia/references.php?id=10041

 

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