Like a famous American frog once said, “It’s not easy being green”, and this is particularly true for our amazing Australian amphibians. Although we have been blessed with a unique frog diversity (Australia is home to over 200 frog species), loads of them are croaking at an alarming rate! Of our frog species, about 43 of them are listed as endangered or vulnerable, and three are presumed extinct. These guys are hopping mad about habitat loss, and they need our help! So, set aside a piece of your patch, and get frog bog building!
Getting Started – Frog Bog Basics
There are a few things we need to be aware of before we consider frog bog construction. Frogs, like us, need moisture, food and shelter, so consider this when placing and designing your frog bog. Ideally, a frog bog would be located in an area of the garden that receives some shade and some sun (about 70% shade and 30% sun). This will ensure that a little bit of algae grows, which is necessary for happy hoppers, and the fallen leaf litter will provide a bit of sustenance for tadpoles in the pond.
While we are talking shelter, the adult frogs need dedicated areas adjacent to the pond where they can hang out! Providing rocks, logs, leaf litter and appropriate shrubs will keep the frogs happy and you will be rewarded with a chorus of frog song all night! While we are talking about the frog song, consider your neighbours when locating the frog pond and keep the bog well away from their windows – especially bedrooms. Frogs can croak and sing all night and nothing says neighbourhood dispute like a badly placed bog!
In the moisture stakes, a good, frog attracting pond needs a total of about 1m³ of water, so consider this also before picking your spot. Frog ponds need to vary in depth, with a deep section of at least 50cm (more on that in the Design and Construction section), so be aware of underground pipes and tree roots in the planning stages. When designing a frog pond, it’s a good idea to consider utilising the natural slope of your block, wherever possible.
Placed in lower areas of your garden, the pond may be fed naturally by runoff rainwater, but the other advantage is that the surrounding ground will stay damp. This makes perfect frog habitat because Australian frogs don’t live in water all the time. In fact, they are used to their watery habitat drying out during summer and so take to the shelter of lush grasses and plants. If designing your pond this way, be aware that many fertilisers, pesticides and herbicides can do dreadful things to frogs, tadpoles and their food sources, so limit your chemical use in the patch!
Get Building – Design and Construction of your Frog Bog
Now that you have located the perfect spot for your frog pond, it’s time to get building. One of the most important aspects of frog bog design is variation in depth. You see, tadpoles need sections of deep water (about 50cm minimum) to keep them cool, and sections of shallow, pooled water. Frogs and tadpoles also need sloped sides on the pond to allow them in and out, and these must not be too steep (they only have tiny legs after all!) or too slippery!
There are a number of pre-made fibreglass ponds that can be simply dug into place, and you can place rocks and logs in one end to create a shallow section. Edges and base can be hidden and the pond softened with the inclusion of rocks and pebbles, and, when the plants go in and around the pond, it will look as though it has always been there!
Another simple method of construction is to excavate a suitable sized hole, with varying depths, and lay a good quality pond liner in it (check with your local garden centre for the best product). The edges and base are also hidden with rocks, pebbles, logs and vegetation. The design below shows the ideal layout of a frog-friendly pond.
Fill ‘er up – Putting Water in the Pond
Might sound simple, but filling up frog ponds can be a bit tricky, especially if your tap water is chlorinated – as it is in many parts of Australia. If this is the case, the water must be allowed to stand, for about 5 days, in a clean container or bucket before it is introduced to the frog pond, to minimise any risk to resident tadpoles and frogs. Water from metal tanks should be treated in the same way, as frogs can be quite sensitive to chemicals that are present in some metal water tanks. Oh, and if you need to top up an inhabited frog pond, don’t just blast the water in. Tadpoles can become over-buoyant if the water contains too much oxygen, so a steady trickle is ideal!
Plants for the Pond, and the Patch
Frogs and tadpoles need a variety of plants at their place, both in and out of the water. Ideally, plants should be indigenous to your local area, and include shrubs, grasses, ground covers and water plants. This combination of plants provides not only shelter and food for tadpoles and frogs, but will attract insects and bugs…..top notch frog tucker! Where you are located in Australia will determine which plants are the most appropriate for your bog, but below is a rough guide to some common Aussie plants that are perfect for frog ponds.
Plants for the Shallow End – include Tussock Sedges (Carex sp.), Sedges (Cyprus sp.), Jointed and Common Rush (Juncus sp.) and Nardoo (Marsilea sp.)
Plants for the Intermediate and Deep Zones – include Marsh Flower (Villarsia exaltata), Purple Loosestrife (Lythrum salicaria), Tassel Sedge (Carex fascicularis), Jointed Twig-rush (Baumea articulata) and Water Ribbons (Triglochin procerum).
Native Plants for the Pond Edge – include Lilly Pilly (Acmena smithii), Dwarf Baeckia (Baeckia sp.), Dianella sp., Purple Coral Pea (Hardenbergia violacea), Mat Rush (Lomandra longifolia), Native Violet (Viola hederacea), Kangaroo Grass (Themeda triandra), Weeping Grass (Microleana stipoides), Wallaby Grass (Austrodanthonia spp.) and assorted Grevilleas and Bottlebrush (Callistemon sp.) to attract insects. Don’t forget to mulch these plants with a nice layer of chunky leaf and wood based mulch (not pine bark or redgum).
Be aware that there are many exotic water plants that are terrible environmental weeds, so be very discerning when you buy, and do a bit of research. Also, avoid plants that form a mat on the top of the water (like Duckweed and Azolla). This stuff makes it difficult for tadpoles to get enough oxygen.
Ponds Can Cop a Caning
As a native Queenslander, I know only to well the horrors of the Cane Toad, and their uncanny ability to seek out frog ponds, pools, dog bowls, and, on one occasion, the hallway in my childhood home! These guys are nasty, and love nothing more than moving into your frog pond. So, there are a couple of things you can do to prevent the Bufus marinus displacing your Kermits.
Firstly, if you live in an area inhabited by cane toads, consider building a raised frog bog with overhanging vegetation. Frogs will be able to access it, but it will certainly prove difficult for the Cane Toad. Secondly, keep an eye out for their eggs in the pond… they are a distinctive blackish “necklace” and will be found clinging to vegetation in the pond. Remove these from the pond, and stick them out in the sun to dry, as this kills off the awful toad spawn. If you are concerned you may be removing frogs eggs, fear not… only cane toads will lay the distinctive necklace of eggs.
Oh, and if you are roving about at night on the hunt for toads, forget the golf club and consider freezing them instead. This is the most humane way to dispose of these hideous creatures, just avoid their poison gland on their backs (best to wear gloves).
Now, what about the frogs?
Okay, there is one rule to remember here… if you build it, they will come! There is no need to head down to the local waterway and collect tadpoles, and, in most places, this is illegal and can draw a hefty fine, so please don’t do it! Frogs will seek out a well designed and well positioned bog, and, although it won’t happen overnight, it will happen!
Once they have moved in, you can pretty much sit back and enjoy. Try and keep pets away from the pond (they do tend to munch frogs), and, don’t clean the pond out too often… this upsets the little ecosystem, and can do more harm than good. Tadpoles can be fed to supplement their algae and insect diet, and the best thing to give them is a bit of washed and boiled lettuce! Sounds revolting, but these guys love it. Don’t go overboard, just a bit now and then.
Oh, most fish and tadpoles don’t really get along that well, so it is best to avoid putting fish in your frog pond altogether. There are a few native species that can co-exist happily with frogs and tadpoles, so ask your local aquarium, or get in touch with your local frog society (check the links below).
Now all that is required is to sit back on a delightful spring evening, and listen to the sound of our amazing native frogs calling well into the night!
Tadpole photo courtesy of www.mybackyard.info
A cute Peron’s Treefrog Tadpole (Litoria peroni)
Native Violet (Viola hederacea), an excellent plant for around your pond
Eastern Common Froglet (Crinia signifera), a regular pond visitor to much of Eastern Australia
Frogs in the Pond!!