Lead exposure and source attribution for a mammalian scavenger before and after a culling program

Area of Science:

• Environmental Science
• Wildlife Toxicology
• Conservation Biology

Background:

• Lead-based ammunition is a major environmental lead source, impacting wildlife, especially scavengers.
• While avian scavenger impacts are known, mammalian scavenger responses to lead exposure require further investigation.

Purpose of the Study:

• To assess lead exposure in Tasmanian devils (Sarcophilus harrisii), a specialized mammalian scavenger.
• To determine if a marsupial culling program using lead ammunition increased lead exposure in devils.
• To identify lead sources by comparing isotope signatures in devil blood to culling ammunition.

Main Methods:

• Blood lead levels (BLLs) were analyzed in 23 devils pre-culling and 15 post-culling.
• Linear mixed effects models were used to analyze BLLs.
• Lead isotope signatures in devil blood were compared to culling ammunition samples.

Main Results:

• No significant difference in mean BLLs was found pre- and post-culling.
• Devils near culling sites had higher BLLs, with elevated levels in 33% post-culling vs. 18% pre-culling.
• One devil showed isotope signatures matching ammunition, indicating scavenging on culled carcasses; most samples indicated other lead sources.

Conclusions:

• While some Tasmanian devils may scavenge lead-shot carcasses, most in the study area did not show significant recent lead exposure from culling.
• Other environmental lead sources are likely significant for this endangered species.
• Even low lead levels can impact the health and immunity of the endangered Tasmanian devil.