Lesser rock skipper
Staurois parvus
Lesser rock skipper
Staurois parvus
CC goal
10 breeders
As at 05/2024
CC goal
500 animals
As at 05/2024
CC goal
10 breeders
As at 05/2024
CC goal
500 animals
As at 05/2024
What do you do when it’s too loud to communicate acoustically? You resort to sign language. Man greift auf Zeichensprache zurück. A whole range of frog species have specialized in living near waterfalls and rapids – extremely loud habitats that drown out classic frog calls. In order to be able to communicate over long distances, they have developed fascinating “sign language” strategies.
The flag alphabet
These frogs have a simple yet effective trick for “conversations” over long distances: they wave. Their webbed feet are strikingly colored, bright white or yellow. They are hoisted like little flags when the frogs stretch out their long hind legs and present their fanned-out webbed feet. The colors can vary depending on the species and age. One of these species is the Lesser rock skipper frog from Borneo, which measures just two to three centimetres.
The waving Indian
Several unrelated frog species around the world belong to the genus Staurois. All of them live in noisy environments and exhibit the same communication behavior. This also applies to Micrixalus kottigeharensis from India.
No waterfall, but other calling males provide too much background noise for Micrixalus kottigeharensis, so that the rivals are also impressed by waving.
The research team from the University of Vienna and Schönbrunn Zoo was able to show that the white, pulsating sound bubble is quickly recognized by opposing males, who then defend their location themselves by calling and waving.
But the males can also become violent. Physical kick attacks are also answered by the opponent – presumably the origin of the waving movement.
Usually signal groups of 4-6 males sit 30-50 cm apart, waving all day long from stones in the river.
Privacy is maintained: if a male enters the amplexus with a female, it is left alone by its competitors.
Not all waving is the same: there are big differences between the various species of waving frogs in the shape and speed of their movements and in the coloration of their feet.
Compared to the Lesser rock skipper from Borneo, the Indian Micrixalus shown here waves less, but calls more.
The feet of the Lesser rock skipper Staurois parvus are much whiter.
A foot is worth a thousand words
When a male frog waves, it lifts one leg, extends it slowly outwards and backwards in an arc and then quickly pulls it back down again vertically. Some waving frogs also use both legs to wave at the same time. When stretched out, the conspicuous bright coloration of the feet is clearly visible. Other males recognize the signal at a great distance and respond accordingly. The waving seems to be mainly used for rivalries between males, it is more or less a long-distance duel – with considerable potential for aggression. Measurements have shown that the more testosterone, the more intense the waving.
Research on the Lesser rock skipper by Schönbrunn Zoo and the University of Vienna
Schönbrunn Zoo is the first zoo in Europe to have created a special kind of ark: it offers breeding and research facilities for the increasingly endangered Staurois.
The Vienna Staurois Container is not only home to the Lesser Rock Skipper Staurois parvus ...
... but also the black-spotted winker frog, Staurois guttatus.
How are the complex movements created? What influences the signal development? These and other questions can be researched under controlled conditions in the „Staurois Arena" at the zoo.
Doris Preininger from Schönbrunn Zoo with students: The Staurois project investigates the evolution of multimodal signals based on behavioral experiments at Schönbrunn Zoo and in the wild.
The underlying mechanism of waving, the neuro-muscular control of the signal and signal evolution, i.e. the development of the signal and its behavioral components, are being investigated at the zoo.
At the same time, comparative field studies in the biotope, as here in India, provide new insights into the development of the signal and the differences in movement sequences, speed and duration.
Model experiments are also used in the field, such as here in the habitat of the Lesser rock skipper in Brunei, Borneo.
Close-range communication
Despite their sophisticated flag alphabet, the winker frogs are not mute.They use calls to communicate at close range. In order to assert themselves against the noise of the current, they use particularly high frequencies. They can also do both at the same time: a male frog can flirt with a female by calling, while waving his legs to keep his sexmates at a distance.
What do you do when it's too loud to communicate acoustically? You resort to sign language. Man greift auf Zeichensprache zurück.
© Norbert Potensky
No more waving?
The Lesser rock skippers of Borneo are only known from a few locations and live in a relatively limited distribution area closely tied to waterfalls and fast-flowing rivers in the rainforest. However, rainforests are also particularly endangered habitats on Borneo and are being cut down at an alarming rate, for example to make way for oil palm plantations. Citizen Conservation’s conservation breeding project is intended to help ensure that we do not one day have to wave goodbye to this species, which is also of particular interest for scientific research.
The world’s first reproduction of the Lesser rock skipper was achieved at Schönbrunn Zoo. Previously, it was not even known what the tadpoles looked like or how they lived. © Norbert Potensky
For breeders
Basic information on biology and breeding
The Lesser rock skipper is only recommended for experienced terrarium keepers who can provide a very wet terrarium with constantly moving water on a permanent basis. Size of the aquaterrarium at least approx. 100 x 60 x 70 cm, cascading waterfall, flowing water, lush planting. 24-25 °C all year round, slightly cooler at night. Feeding with small feeding animals.