Using DNA metabarcoding as a novel approach for analysis of platypus diet.

Platypuses (Ornithorhynchus anatinus) forage for macroinvertebrate prey exclusively in freshwater habitats. Because food material in their faeces is well digested and mostly unidentifiable, previous dietary studies have relied on cheek pouch assessments and stable isotope analysis. Given DNA metabarcoding can identify species composition from only fragments of genetic material, we investigated its effectiveness in analysing the diet of platypuses, and to assess variation across seasons and sexes. Of the 18 orders and 60 families identified, Ephemeroptera and Diptera were the most prevalent orders, detected in 100% of samples, followed by Trichoptera, Pulmonata, and Odonata (86.21% of samples). Caenidae and Chironomidae were the most common families. Diptera had a high average DNA read, suggesting it is an important dietary component that may have been underestimated in previous studies. We found no variation in diet between sexes and only minimal changes between seasons. DNA metabarcoding proved to be a highly useful tool for assessing platypus diet, improving prey identification compared to cheek pouch analysis, which can underestimate soft-bodied organisms, and stable isotope analysis which cannot distinguish all taxa isotopically. This will be a useful tool for investigating how platypus prey diversity is impacted by habitat degradation as a result of anthropogenic stressors.

Headstarting as a cost-effective conservation strategy for an endangered mammal.

Introduced predators threaten prey species worldwide, but strategies to protect vulnerable wildlife from introduced predators can be expensive, time-consuming, and logistically difficult1,2. Novel conservation strategies that reduce predation affordably and efficiently must be explored. 'Headstarting' is one such strategy, whereby prey are isolated from predators only during the critical early life stage before being returned to the wild, thus improving juvenile survivorship and recruitment to contribute to an increase in population growth3. Headstarting is a particularly useful conservation strategy for species facing higher levels of a threatening process during only the early part of their life history when mortality rates are higher, and has demonstrably improved conservation outcomes for birds and marine species3,4. Here we report findings from the first known headstarting program for a terrestrial mammal, the endangered bridled nailtail wallaby (Onychogalea fraenata) at Avocet Nature Refuge (henceforth 'Avocet') in Queensland, Australia.