The Breeding Technique

Sam Forster

The Green Treefrog, or Litoria caerulea is a relatively simple species of frog to breed provided you understand the natural behaviour of these frogs and are able to replicate it in the captive environment. Below are three graphs, the average rainfall, the average maximum and minimum temperatures and the average number of daylight hours in the frog's natural habitat. Through analysis of this data it is possible to understand the significant factors, which must be reproduced to initiate breeding.

• Average Yearly Rainfall
• Average Daylight Hours
• Average Temperatures

Many people find it incredibly difficult to breed these frogs. The main reason for this is, people think by setting up a rain chamber and 'dumping' the frogs in they will immediately recognise that it is the wet season and time to breed. This is not the case; to breed these frogs requires a great deal of conditioning and effort. Yes, some people do breed these frogs once or twice by chance but not everyone is that lucky, the way I will describe is a proven method and will hopefully work for you too.

Obviously the most significant environmental cue required to induce breeding is an increase in rainfall. From a life history perspective this appears reasonable, as breeding is not possible without water and thus it is a logical cue. Unfortunately this is not the only factor. As in any species reproduction is a significant energy expenditure and thus the frogs must prepare many weeks or even months ahead of the event. This explains the failure of frogs to breed when introduced to a rain chamber without proper preparation. The two obvious environmental factors that may act, as the signals to the frogs to commence this preparation are temperature and daylight hours.

Many breeders recommend temperature as the significant factor. They suggest frogs undergo a cooling period in the months leading up to the breeding. While this approach can be extremely successful and will usually induce breeding it is extremely dangerous to the health of the frogs and thus should be avoided if a better alternative is available. This alternative is daylight hours. From the graphs it is possible to determine both temperature and daylight hours vary significantly over the year in the frogs natural habitat but daylight hours has minimal if any detrimental effects on the frogs health and thus is the preferable method.

To attempt to breed these frogs the first stage is to introduce the correct day/night cycle. As you are controlling the temperature the actual time of year has no bearing on the time of year you chose to allow your frogs to experience. For the purpose of this description the breeding attempt will occur in late January as is the case in the natural environment. The first stage to initiate the breeding is the introduction of day/night cycles appropriate to the time of year. The suggested daylight hours over the course of a year are outlined below.

February to April	May to July	August to October	November to January
12 hours	11 hours	12 hours	13 hours

The second factor you will need to simulate in order to induce breeding is the monsoonal rains of the wet season. This replication is not as easy as it seems. Most people simply set-up a small pump in their enclosure or rain chamber and circulate the water to a rain bar. The important factor they forget is the monsoonal rains are a few degrees cooler than the temperature of the water. This is the most common reason for failure, as the frogs simply do not appear to associate the rains with the arrival of monsoonal because of the lack of temperature change. This temperature change can be simulated through the use of a cooler, which can be obtained in one of two ways

• Commercial Cooler
  A cooler is a device, which as the name suggests cools the water as it passes through it. These devices are commonly used with aquarium however it will cost you in the vicinity of $800(AU)
• DIY Cooler
  For approximately $100(AU) a perfectly acceptable cooler can be created, the designs for which be found here.

Assuming you have your rain chamber set-up you will be able to move on to the next step, in early January. The morning before you intend to move the frogs to the rain chamber feed each frog about eight to ten crickets. This will allow you to leave the frogs in peace while they breed. Introduce the frogs in a ratio of 2 to 3 males to every female and turn on the rain at approximately five o'clock in the evening. This should remain on for eight to nine hours each night for the next few days, or until the eggs are laid. At this time you may also have a tape playing of the frogs call, however, this is usually not necessary.

If all went well you will now have approximately 1000 eggs per female. The general rule for tadpoles suggests 10 tadpoles to the gallon. At this stage you may do your calculations and work out that for 1000 tadpoles you only need 100 gallons and decide you can easily house them, however the problem exists when 1000 tadpoles become 1000 baby frogs. The costs involved with housing and feeding this many frogs are astronomical. The truth is, most people can only successfully keep around 50 frogs. The options with the rest are problematic, it may be possible to give some away as tadpoles, however, most will end up as fish food.

The tadpoles will survive in almost any water condition with a temperature between 26 and 29 degrees Celsius, and a pH of 7.0 being optimal. The tank should include three centimetres of gravel, a 75% covering of plants and filter of your choice. The tadpoles should be fed as much flaked fish food as can be consumed in half an hour on two occasions each day.

Frogs generally remain tadpoles for 15 to 20 days, however, this process can be accelerated by decreasing the water level. This deceives the tadpoles and elicits a natural survival behaviour designed to survive the arrival of the dry season. This behaviour causes the tadpoles to become frogs more quickly, to avoid being trapped as tadpoles in a dried up pond, however, this does not mean they will reach maturity in a shorter time period. They will simply spend longer as juvenile frogs than those, which have grown at the natural rate. Once the tadpoles begin becoming frogs it is vital to have some rocks or floating plants, which emerge from the water. This will prevent newly metamorphosed frogs from drowning. It is also important to remember to have a secure cover over the tank to prevent escape.

When the frogs have permanently left the water and are no longer absorbing their tails you can move the frogs to a separate enclosure and begin offering pinhead crickets (see articles on breeding crickets). As a final note I believe that full spectrum UV lighting is crucial for the growth of tadpoles and frogs and recommend that they be fitted to all tanks.

If you would like any more information on this topic or have any comments or suggestions please feel free to email me.