Mammals
In 1995, hunters in Montana started noticing deformities such as pronounced overbites, abnormal genitalia and abnormal jaw length in the white-tailed deer they were hunting. It prompted Jonathan Jenks, a wildlife ecologist, to conduct his own studies and he found deer with higher levels of neonicotinoid (neonics) in their spleens had pronounced overbites. He also found deer that had not been intentionally exposed to neonics in his study already had them in their system.
Because neonicotinoids (neonics) bioaccumulate and take between 1-19 years to break down in the environment, mammals are at increased risk of exposure and toxicity through water, soil, food (plant consumption), and air contamination. Neonics have been detected in wild birds of prey, rodents, fish, lizards, frogs, and deer. They are exposed by eating treated neonic coated seeds, contaminated prey or coming into contact with tainted field runoff.
Neonics are being found throughout the landscape in areas where they were not applied. Studies have shown neonics have the capacity to alter the structure of the nervous system and, consequently, its correct functioning, both during development and in adulthood of mammals.
Abnormalities in genitalia and jaw length in deer are attributed to neonic exposure.
Similar to Christy Morrisey’s, an ecotoxicologist at the University of Saskatchewan, research showing that white-crowned sparrows feeding on neonics could not find true north for weeks after being exposed, affecting their migratory patterns, insectivorous bats exposed to neonics adversely impact their echolocation system. Echolocation is a spatial hearing skill that uses reflected sound to help animals navigate, hunt, and avoid obstacles. Neonics may also lower the immune system of bats making them more vulnerable to disease, poison them by eating affected insects and depleting insect populations means a depleted food source for them.
In Minnesota, researchers found neonics in 61% of 799 deer spleens tested in 2019. But the chemical was found in 94% of 496 samples collected in 2021.