The bertam palm's flower buds house yeast communities that ferment the nectar where it sits. Measurements of that nectar have found alcohol contents reaching around 3.8 per cent, comparable with a beer and among the highest recorded in any natural food, and the palm's flowers are visited nightly by several small mammals including the pen-tailed treeshrew.
What makes the case notable is what does not happen. Treeshrews studied in Malaysia fed for several hours a night, taking doses equivalent to ten or twelve glasses of wine when scaled to body weight, without observable drunkenness. A biomarker of alcohol dehydrogenase measured in their hair indicated they process ethanol along a pathway that humans use less heavily.
The headline version of the story, that the animals drink heavily every night for pleasure, overstates it. The relationship looks mutualistic: the mammals get a reliable energy source and the palm gets pollinated. How the treeshrews benefit, and what a consistently high blood alcohol content does to them, remains unclear, and the original study covered few individuals.