“Chirp” calls of adult white-nosed coatis (Nasua narica) were measured and compared to determine form and function of these frequently emitted vocalizations. Behavioral contexts during vocalizations were documented, and chirp calls were tape recorded and analyzed using a digital spectrograph. Also, a bat detector was used to determine whether ultrasonic frequencies were emitted in chirps. Duration of the chirp calls was 0.146–0.202 s. Spectrogram analyses revealed that the lowest frequencies of the chirps averaged 4.66–11.83 kHz and that the highest frequencies averaged 1417.66 kHz. Ultrasonic frequencies (30–55 kHz) also were detected in chirp calls. Chirps differed among individuals regarding the differential frequency between the 1st and 2nd resonance bars (P ≤ 0.01). Chirps seem to function as contact calls for this social mammal because they were emitted only while coatis were moving. The short duration and high frequency of the calls may allow for contact with nearby group members while minimizing auditory detection by predators. Unique features of each coati's chirp also may allow individual recognition.