Many bat species around the globe are believed to be threatened by extinction due to a long list of ongoing threats, including habitat loss, bushmeat hunting, wind energy production, and infectious diseases. White-Nose Syndrome - a fungal disease affecting hibernating bat species - has alone caused a dramatic decrease in bat populations across North America, killing around 6 million individuals as of 2018.

However, in light of new research, advocates believe chemical pest management compounds could be contributing to the species’ alarming decline.

Growing awareness of the hazards inherent in the use of rodenticides and pesticides is driving increasingly ardent demand for legal and regulatory parameters throughout British Columbia and parts of the United States. But new research indicates that rodenticides and other chemicals commonly used to manage unwelcome wildlife and insects are having a greater impact on the ecosystem than previously realized. While secondary impacts on non-target predator species such as owls, falcons, and coyotes are well documented, evidence of bioaccumulation within less obvious members of the food chain - including bats - is raising even more concerns.

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Additional Research

A recent New Zealand study confirmed the presence of anticoagulant rodenticides (diphacinone) in an insectivorous bat species (Mystacina tuberculata) (Dennis and Gartell, 2015). Two likely routes of exposure were proposed: direct consumption of toxic bait or secondary poisoning after eating arthropods that had consumed toxic bait. 

“At necropsy, adult bats showed gross and histologic hemorrhages consistent with coagulopathy, and diphacinone residues were confirmed in 10 of 12 liver samples tested. The cause of mortality of pups was diagnosed as a combination of the effects of diphacinone toxicity, exposure, and starvation. Diphacinone was also detected in two of 11 milk samples extracted from the stomachs of dead pups.”

See also (Eason and Spur, 1995), a literature review regarding Toxicity and Sub-lethal Effects of Brodifacoum in Birds and Bats. 

Subsequent studies have similarly cited insects and water sources as potential pathways for species previously  believed to be unlikely victims. For example, see (Regnery et al, 2018). “Anticoagulants accumulating in aquatic wildlife are likely to be transferred in the food chain, causing potentially serious consequences for the health of wildlife and humans alike”

Report a Sick or Dead Bat