Frogs on the Farm

Ponds for Frogs

Most tadpoles of pond breeding frogs are highly vulnerable to predators and most pond frogs prefer to breed in areas with low predator populations. One tactic is to breed in waters that dry down periodically, which kills predators and water born diseases. These temporary ponds will be free of fish after flooding rain, assuming there is no fish recruitment through migration from local permanent water bodies, and the ponds will take time to develop a population of air born invertebrate predators such as dragon fly larvae and beetles. A restricted number of frogs breed in waters inhabited by predatory fish. Their tadpoles either have specific chemical or behavioural defences adapted to the natural fish species in their breeding areas. However, these tadpoles are still vulnerable to introduced fish species.
Shallow flooded grassland is also a favoured site of some winter breeding species as water may remain for long periods in such a habitat during cool weather. The tadpoles are sheltered from bird and fish predation by the grass matt, and the cold weather limits water insects. Although there are several small native fish in permanent water bodies, only the introduced Plague Minnow (Gambusia holbrooki) is capable of rapid colonisation of recently flooded areas. This fish will prevent successful tadpole survival in open water bodies, and severely reduce survival in highly vegetated water bodies.
Generally the time for tadpole development to frogs is 6 to 24 weeks, with summer breeders having a shorter period than winter species. Rainfall patterns may vary widely from year to year and ponds which hold water for long periods, in a wet year with consistent rainfall, may not hold water long enough for tadpole development in dry years. Therefore it is desirable to have a range of pond types with different filling and drying patterns allowing the successful reproduction of the types of frogs in the area.
Adult frogs need shelter such as trees with cracks or loose bark, logs, fallen bark, loose stones or thick vegetation. Grazing areas can incorporate adult habitat for frogs in sympathy with production and sustainable management practices. One successful strategy is to fence small areas on the margins of pond allowing the growth of dense vegetation to provide adult frog shelter. An additional benefit is that enclosed trees may also regenerate through seedlings or suckers. Grazing of ponds should not affect the survival of tadpoles. Frogs increase pasture production by feeding on insects and providing food for birds such as Ibis, Cranes and Egrets that also eat pasture pests.