Friday, 15 February 2008

#46 The sad face of a Green Tree Frog

Green Tree Frogs with their ho-hum expression, warty throat and long, clumsy-looking digits, are absolutely delightful creatures. But I haven't always been so endeared to these large green amphibians that used to glare at me from the toilet bowl several times a day.

There was a time, I am embarassed to admit, that I wouldn't use the toilet unless my 7 year-old son was at home to retrieve this fellow from the bowl. And then he'd be back again; and again. Indoor toilets are no guarantee that you'll never be surprised by this fellow either. If they want to get in, they'll get in.

But how could you not love this face?

Amphibian means 'two lives'. Most amphibians are charactised by a distinctive aquatic larval stage called the tadpole. These tadpoles metamorphose into the adult form and then usually leave the water in which they developed. Typically, tadpoles develop in fresh water, and amphibians in general have a low tolerance of saline conditions.

Most larval amphibians possess gills, while adults are air-breathing and possess lungs. All are cold-blooded.

With the exception of toads, frogs usually have a moist, highly permeable skin, and therefore, in order to avoid dehydrating must live in moist places. Even desert species are usually found close to water, and are usually only active after rain.

Green Tree Frog - Litoria caerulea

Tree frogs have astonishingly adhesive toe pads which enable them to climb all types of surface including glass. The Green Tree Frog is probably Australia's best known frog and is found throughout the eastern and northern parts of the country.

Green Tree Frogs sometimes have white irregular spots

This docile frog is one of the biggest frogs (up to 10cm), and although found in many types of habitat, it is usually found around human habitation in mailboxes, meter boxes, downpipes, bathrooms and toilets. In their natural environment they hide in hollow tree limbs and rock crevices.

I evicted this frog from the toilet at my parent's house and found him a nice damp spot by the 'frog pond', but surprise, surprise, he found his way back to the toilet.

Green Tree Frogs, Litoria caerulea, are nocturnal and will emerge from their daytime sleeping hide after dark to feed on insects. It will take anything that fits into its gaping mouth, often shoving it in with its hands. Occasionally I find one on my back porch taking advantage of insects attracted to the outside light.

As well as calling to attract a mate during spring and summer, Green Tree Frogs call at other times, especially during or after rain. Its native predators are snakes, lizards and birds.

Frogs' eyesight and hearing

Frogs need good eyesight as they usually only eat prey that is alive and moving, therefore they generally have large, bulging eyes. They are located on top of the head to allow a wide field of view. As frogs are nocturnal, their night vision is generally well developed.

A frog can protect its eyes with a transparent 'eye-lid' called a nictitating membrane. This transparent membrane permits the frog to see underwater.

The transparent eye membrane

A frog hears through a circular eardrum (the tympanum) located on each side of its head behind the eye. Sound enters the ear via the tympanum which vibrates back and forth. Fluid-filled sacs of the inner ear trigger neural signals which travel to the brain.

The tympanum (eardrum) behind the eye

Frogs make their calls with the help of one or two pouches of skin called vocal sacs. Sound is produced when air rushes over the vocal chords on its way from the lungs into the vocal sacs. The vocal sacs work like echo chambers to amplify the sound.


Unfortunately, I don't hear the call of the Green Tree Frog in the Hunter Valley as frequently or in such numbers as when I was a child. Populations are thought to be declining due to habitat modification (land clearing, introduction of invasive weeds, filling of ditches and drains), and pollution.

The thin, porous skin of frogs and tadpoles makes them sensitive creatures. Through this skin, they absorb chemicals from the air and water, therefore, in areas where water or air pollution has occurred, the local frog community will be affected and there are likely to be very few frogs.

Well, come on in - no need to knock

In order to create a healthy environment in which to encourage frogs to live in your garden, you will need to supply clean water such as a small pond with some surrounding vegetation for protection; keep the use of chemical fertilizers, herbicides and pesticides to a minimum; and control pets.

Frogs will need help and consideration from all of us (industry and residential) if they are to thrive as they should.

The night-time frog chorus of several frog species in the paddock adjoining our house-yard following prolonged periods of rain over summer in the Hunter Valley, is an encouraging sound indeed.


Anonymous said...

A sheer delight, not only from the well-written information but also those appealing photographs.
Well done Gaye.

Evan said...

Nice post, and great photos. I'd change one thing though. The "suction caps" is misleading, as the frogs use capillary forces to stick to surfaces, not suction. Toe pads are the normal term for that body part.


Denis Wilson said...

Hi Gaye

Love the Green Tree Frogs. I don't get them here, but my former partner grew up in Brisbane, where there was always a GTF in the outside dunny, and one over the light on the back porch (to catch moths).

Hopefully after all the rain this year, in the Hunter, your Frogs are having a good year.



Gaye from the Hunter said...

hi Lola, Evan and Denis,

I'm pleased you enjoyed my adorable Green Tree Frogs. Thank you all for taking the time to comment.

Evan, I appreciate your input to suggest a correction. I have done some reading on this now, and it is most interesting. Thank you.


Blogger Bill said...

I wish we had them here in Victoria. They look like fun!

Gaye from the Hunter said...

hi Bill,

I have been fortunate to see new (to me) species of frogs on night time walks in my yard recently, no doubt because of the prolonged rain providing waterholes for mating opportunities.

And, yes, frogs are fun to observe !


Julie said...

I am so envious. As I grew up in Denman, I had GTFs. At that time, I simply thought of them as slimey. Your post brings back wonderful memories. I like the comment about the toe-pads too. Although, your Jacky must have good toe-pads too, going by the photo of him half-way up the window.

Gaye from the Hunter said...

hi Julie,

funny, isn't it, how, without experience, it is presumed that frogs are slimy. I also thought this when I was younger.

Jacky, my water dragon, has scaly toes with long sharp claws making climbing rough surfaces easy.

Oh, and I found a small 'mummified' frog in the shed yesterday - odd, but interesting.


David said...

Hi Gaye -

I LOVE frogs. GTFs included. Fantastic photos and write up as per normal!


Sue said...

Hi Gaye,
I love that face!

I wish the Green Tree Frogs were around in the suburbs of Sydney. In fact, I'm quite jealous!

I have Peron's Tree Frogs, Striped Marsh Frogs and Common Eastern Froglets in my backyard. I hope you post some pictures of your newly discovered species soon.

I found a mummified froggie once too. He got caught between the Sliding glass door and the sliding screen door one night while catching dinner. When the hot sun beat down on him next day he could not escape. :( Someone had left the screen door open and the glass door closed during the evening. When we locked up at bedtime the screen door was closed, trapping the frog. I always check now.


Gaye from the Hunter said...

hi David,

thanks. It's hard not to like the green tree frogs and I'm pleased to be able to show of my beaut backyard frogs.


Gaye from the Hunter said...

hi Sue,

a new reader! Welcome.

To have three species of frogs in your suburban Sydney backyard, you must be doing plenty right - congratulations! It is just so heartening to know that frogs do survive in such intense residential areas. Thank you for sharing that.

I will have more frog entries shortly.

Thank you for leaving a comment, Sue.


Junior Lepid said...

Hello Gaye,

I found your brilliant Blog whilst Googling images for Garden Orb spiderlings!

I am impressed. We have quite a few similar interests in nature. Conservation, preservation and species encouragement!

I am from Victoria and made a point of establishing a frog-friendly garden. Litoria ewingi regularly spawn in my pond. I also have a small house dam in which they spawn as well as several other frog species.

I don't have the lavatory problem - but I do have a laundry problem with L. ewingi!

From one photographer to another, you images are excellent.

Gaye from the Hunter said...

hi Junior Lepid,

I'm so pleased that you found my nature blog, for, now I have been directed to yours. I have added a link to your blog on my home page as you are sharing such useful and fascinating nature observations.

I look forward to checking out your blog on a regular basis.

Happy nature observing !!


Anonymous said...

Thanks for this great blog!

I live in Newcastle and we have two frog ponds set up, but so far have only seen the striped marsh frog. I miss beautiful tree frogs - they were everywhere growing up in Qld as a kid. I'm now hopeful we might be able to attract some even this far south too.


Gaye from the Hunter said...

Hello Laura,

thank you for leaving a comment. Yes, I recall growing up int he Hunter Valley hearing and seeing Green Tree Frogs so often that it was nothing special. Now, it is very special to hear or see a Green Tree Frog in the garden.

Congratulations on providing some habitat for frogs, and I hope you are rewarded by many healthy frogs coming and going.

Kind regards,
Gaye (from Singleton)

Becky Layton said...

I actually have a question rather than a comment. We have recently moved to Darwin and have discovered a green tree from living in our ensuite toilet. Whilst I have no problem with it living there, I am wondering if it will survive or whether its chances would be better if we moved it out side somewhere. It is full grown, but I have no idea how ling it has been in the house (which is fully screened so I have no idea - or rather idea what it is eating). Do you have any suggestions?

Anonymous said...

I have found several frogs, and even lizards, naturally "mummified". One bigger frog, several tiny ones behind the couch in my living room, and two more tinies on the back patio just the other day. How do they die, and how are they mummified?