From ponds to patios: evidence of frog reproduction and recruitment in residential gardens

Residential garden ponds contribute significantly to the available aquatic habitat within urban landscapes. Although garden ponds have novel biotic and abiotic characteristics, they are used by a variety of wildlife. However, whether they support healthy animals, reproduction and recruitment, critical for longer-term sustainability, is largely unknown. We addressed this knowledge gap using frogs as a case study taxon by investigating species assemblage, size (snout-vent length, SVL), body condition (scaled mass index, SMI), reproduction and recruitment in urban gardens with ponds relative to natural wetlands in southwestern Australia. Based on monthly sampling of 21 urban gardens and 6 wetlands between September 2023 and March 2024, we found that gardens supported a less diverse species assemblage than wetlands. Garden frogs were up to 39.5% longer in SVL but did not differ in SMI to those in wetlands. Of species occurring in both habitats, 75% (3) called earlier and/or for longer in gardens compared to wetlands. Over 40% of garden ponds supported reproduction of motorbike frogs (Litoria moorei) and of these 45% supported recently metamorphosed juveniles. Reproduction of the other species in gardens was minimal. This study is one of few to investigate the ability of urban habitats to support critical aspects of life history and demonstrates that residential garden ponds can sustain healthy adults, reproduction and recruitment for some species.