Controversial glyphosate-based herbicides (GBHs) are the most frequently
used herbicides globally. An increasing number of studies have
identified GBH residues in soil, water, and even human food that may
expose nontarget organisms including wildlife, livestock, and humans to
health risks. After a heated debate, the European Union allowed the use
of GBHs to continue until 2022, after which their risks will be
re-evaluated. Thus, decision makers urgently need scientific evidence on
GBH residues and their possible effects on ecosystems. An important,
yet neglected, aspect is to assess whether animals show preference or
avoidance for GBH-contaminated food, as it can influence the likelihood
of adverse health effects in wildlife. Here, using Japanese quails (Coturnix japonica)
as our model, we show that females preferred GBH-contaminated food
compared to control food. In females, exposure to GBHs caused delayed
plumage development, and GBH residues were present in eggs, muscles, and
liver. These results indicate that female preference is not adaptive,
potentially exposing nontarget animals to greater risk of adverse
effects of GBHs in natural and agricultural environments. Our results on
tissue residues suggest that further studies are needed to understand
the risks of such residues in the food chain.