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Frog Facts: First Discovery of Egg Care by a Southeast Asian Treefrog

C. vittatus

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The breeding habits of a poorly-studied treefrog have recently grabbed the attention of herpetologists and amphibian enthusiasts. Although it is small in size and lacks a common name, Chiromantis hansenae is quite special. Recent research has revealed it to be the only Southeast Asian treefrog known to provide parental care to its eggs. Furthermore, it breaks the typical rules that apply to most other egg-guarding frogs in important ways. Very little is known about Chiromantis hansenae, which until now was thought to be an “un-remarkable” little frog – a clear sign that important discoveries await those willing to search.


Eggs Die Without Mom’s Care

Chiromantis hansenae’s unexpected egg-brooding behavior was first observed by researchers from the National University of Singapore. Writing in the journal Ethology (V. 119, N. 8, p 671-679), they describe how females deposit egg masses in trees and then cover the eggs with their bodies. Egg-attending treefrogs sometimes descend to the ground and soak for a time in nearby ponds, after which they return and re-position themselves above the eggs. This behavior apparently supplies the eggs with water and also limits the amount of water lost via evaporation…most of the egg masses from which females were removed (by researchers) dried up and failed to hatch.


Midwife Toad with eggs

Uploaded to Wikipedia Commons by Fice

Chiromantis hansenae differs from most other egg-brooding frogs in several important ways. In other species, few large eggs are produced, and the male provides most or all of the parental care (please see photo of male Midwife Toad carrying eggs).  Such eggs are generally deposited on land, and direct development (from egg to small frog) is typical. Chiromantis hansenae, by contrast, produces many tiny eggs and deposits them above-ground, and tadpoles rather than small frogs emerge from the eggs.


Conservation Implications

Why has this unique breeding strategy evolved, and how many other species rely upon it? Answering such questions is crucial if we are to understand and conserve the world’s frogs, many of which are facing an extinction crisis.


That such a small, unassuming frog could hold these secrets should inspire us to look at all creatures with deep respect and interest. One never knows where the next unforeseen discovery will arise, or how important it will be from a conservation perspective. Despite Southeast Asia’s incredible diversity of amphibians, the study mentioned above is the first to closely examine parental care in any of the region’s frogs.


Unfortunately, little is known of Chiromantis hansenae’s natural history; the range, usually given as Thailand and Cambodia, is poorly-defined. The IUCN lists this frog as “data deficient”, and some herpetologists doubt that it is a distinct species, classifying it instead as the widely-ranging C. vittatus (note: the first photo, above, is of C. vittatus; you can see a video clip of C. hansenae here ).


Chinese Flying Frog

Uploaded to Wikipedia Commons by Dger

Related Frogs

Chiromantis hansenae is classified in the family Rhacophoridae, along with several treefrogs that are popularly-kept in captivity by amphibian enthusiasts. Included among them are two of my personal favorites, the Chinese Flying Frog (Rhacophorus dennysi, please see photo) and the African Gray Foam Nest Frog (Chiromantis xerampelina).




Further Reading

Tree Dwelling, Wood-Eating tadpoles Discovered!


The Fang-bearing Tadpoles of the Vampire Frog



About Frank Indiviglio

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Being born with a deep interest in animals might seem unfortunate for a native Bronxite , but my family encouraged my interest and the menagerie that sprung from it. Jobs with pet stores and importers had me caring for a fantastic assortment of reptiles and amphibians. After a detour as a lawyer, I was hired as a Bronx Zoo animal keeper and was soon caring for gharials, goliath frogs, king cobras and everything in-between. Research has taken me in pursuit of anacondas, Orinoco crocodiles and other animals in locales ranging from Venezuela’s llanos to Tortuguero’s beaches. Now, after 20+ years with the Bronx Zoo, I am a consultant for several zoos and museums. I have spent time in Japan, and often exchange ideas with zoologists there. I have written books on salamanders, geckos and other “herps”, discussed reptile-keeping on television and presented papers at conferences. A Master’s Degree in biology has led to teaching opportunities. My work puts me in contact with thousands of hobbyists keeping an array of pets. Without fail, I have learned much from them and hope, dear readers, that you will be generous in sharing your thoughts on this blog and web site. For a complete biography of my experience click here.
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