Prairie dogs live in dense colonies where a sentinel's warning benefits many relatives at once. Their alarm calls are short repeated chirps, and spectrographic work by Con Slobodchikoff and colleagues, working chiefly with Gunnison's prairie dogs, found that call structure differs reliably between predator classes, so that hawks, coyotes, domestic dogs and humans elicit distinguishable vocalisations that in turn elicit different escape behaviour.
Further experiments walked human observers of differing height, body shape and shirt colour through a colony and reported that the calls varied with those features too. Playback experiments have shown that listening prairie dogs respond appropriately to recorded calls in the absence of any predator, which is the key control.
The interpretation is where care is needed. Describing this as a language with nouns and adjectives overstates what has been demonstrated. What the data support is that the calls are functionally referential and encode graded information about the threat, not that they have grammar.