Further investigation of lead exposure as a potential threatening process for a scavenging marsupial species.

There is a growing recognition of the harmful effects of lead exposure on avian and mammalian scavengers. This can lead to both lethal and non-lethal effects which may negatively impact wildlife populations. Our objective was to assess medium-term lead exposure in wild Tasmanian devils (Sarcophilus harrisii). Frozen liver samples (n = 41), opportunistically collected in 2017-2022, were analysed using inductively coupled plasma mass spectrometry (ICP-MS) to determine liver lead concentrations. These results were then used to calculate the proportion of animals with elevated lead levels (>5 mg/kg dry weight) and examine the role of explanatory variables that may have influenced the results. The majority of samples analysed were from the south-east corner of Tasmania, within 50 km of Hobart. No Tasmanian devil samples were found to have elevated lead levels. The median liver lead concentration was 0.17 mg/kg (range 0.05-1.32 mg/kg). Female devils were found to have significantly higher liver lead concentrations than males (P = 0.013), which was likely related to lactation, but other variables (age, location, body mass) were not significant. These results suggest that wild Tasmanian devil populations currently show minimal medium-term evidence of exposure to lead pollution, although samples were concentrated in peri-urban areas. The results provide a baseline level which can be used to assess the impact of any future changes in lead use in Tasmania. Furthermore, these data can be used as a comparison for lead exposure studies in other mammalian scavengers, including other carnivorous marsupial species.

Toxic time bombs: Frequent detection of anticoagulant rodenticides in urban reptiles at multiple trophic levels.

Anticoagulant rodenticides (ARs) are regularly used around the world to control pest mammals. Second-generation anticoagulant rodenticides (SGARs) are highly persistent in biological tissue and have a high potential for bioaccumulation and biomagnification. Consequently, exposure and poisoning of non-target organisms has been frequently documented, especially in countries with unregulated AR sales and usage. Most of this research has focussed on rodent-predators, usually raptors and predatory mammals, although exposure has also been documented in invertebrates and insectivorous fauna. Few studies have explored non-target exposure in reptiles, despite species sharing similar trophic positions and dietary preferences to other exposed fauna. We tested three abundant urban reptile species in Perth, Western Australia that differ in diet and trophic tiers for multiple AR exposure, the dugite Pseudonaja affinis (rodent-predator), the bobtail Tiliqua rugosa (omnivore) and the tiger snake Notechis scutatus occidentalis (frog-predator). We found frequent exposure in all three species (91% in dugites, 60% in bobtails and 45% in tiger snakes). Mean combined liver concentrations of ARs of exposed individuals were 0.178 mg/kg in dugites, 0.040 mg/kg in bobtails and 0.009 mg/kg in tiger snakes. High exposure frequency and liver concentration was expected for the dugite. Exposure in the other species is more surprising and implies widespread AR contamination of the food web. We discuss the likelihood of global AR exposure of urban reptiles, highlight the potential for reptiles to be important vectors of ARs in the food web and highlight implications for humans consuming wild reptiles.