whistling tree frogs

Eleutherodactylus johnstonei

It has been raining a lot in Bermuda these past two weeks – apparently 9 inches so far in August. So the whistling tree frogs have been squeaking by day as well as by night. For such tiny creatures they make an almighty racket.

I have read that they were an accidental introduction to the island at some point during the late 1800s, from the Lesser Antilles. I had to look up where that was – seems to be the Eastern islands of the Caribbean, the ones that include Barbados and Jamaica.

For something that makes soo much noise they are absolutely tiny:

10-25mm long

There are over 180 species of Eleutherodactylus frogs.
They are listed on the IUCN “red list” meaning they are under some threat of extinction. It is a low grade threat for the E. johnstonei, though for another species once found in Bermuda, the E. gossei, the culture shock was clearly too great and none have been seen here since 1994.

Other names for them are “Rain Frogs” which makes sense, but also “Robber Frogs” which is, according to wikipedia, because of the noise they make – never met a robber personally but I somehow doubt they make that much noise.

I wanted to find out how they actually make the noise and came across “Frog Forum” where I was totally sidetracked by the story of the whistling frog that didn’t whistle – it has a sad ending 😦
I was none the wiser about why the noise is so loud but have learned that only the male frogs peep, in part to attract a mate and in part to defend their territory. I presume they inflate their throat sac to amplify the sound. I came across an academic article describing an experiment to ascertain the female tree frog’s preference in whistles – long and loud was the conclusion. Their ears have evolved such that the female will hear a very narrow range of frequencies due to the specific anatomy, while the male is possibly deaf to most things! (there’s a joke in there somewhere)

A kids biology site enlightened me on their reproduction:- the eggs provide a one stop shop resulting in mini frogs hatching, no tadpole stage. The hatching apparently looks like a mass melting leaving small frogs who jump off pretty quickly – sadly not yet captured on YouTube. Male frogs watch over the eggs which the female leaves in wet flower pots or walls or under wet stones. Interestingly the period until the egg hatches is variable and can depend on external triggers. This phenomenon is phenotype plasticity, not genetic. So within the one genus Eleutherodactylus are a whole range of reproductive behaviours – hatching as tadpoles or froglets with tails or mini adult frogs. The just-hatched-tree frogs must be minuscule – I will need a magnifying glass on my next tree-frog-hunt, Dora eat your hat!

On occasion one of the little critters (in the middle of the night aka little blighters) makes an exploratory jump indoors. You can hear it … but finding it and catching it is another matter entirely. And because its probably as humid indoors as out then they don’t seem to have the sense to head towards an open window.

On balance I like the whistling frogs. In case I miss them on return to UK I have downloaded an mp3 file. There are lots to choose from, one even entitled “Trilling tree frogs for inner health and tranquility”. You can even get them singing Christmas songs