The effect of localized disturbance on the acoustic behavior of the common tern (Sterna hirundo).

In this study, passive acoustic monitoring was used to assess the impact of investigator disturbance on the acoustic behavior of a colony of common terns. A graded antipredator response in the colony was hypothesized, which would result in an increase in acoustic energy with increased proximity to investigator disturbance. Human disturbance was found to result in a significant increase in acoustic energy within 20 meters of recorders, though not from farther distances.

Correction: BatCount: A software program to count moving animals.

[This corrects the article DOI: 10.1371/journal.pone.

Characteristics of wild moose (Alces alces) vocalizations.

Moose are a popular species with recreationists but understudied acoustically. We used publicly available videos to characterize and quantify the vocalizations of moose in New Hampshire separated by age/sex class. We found significant differences in peak frequency, center frequency, bandwidth, and duration across the groups.

Graded alarm call behavior in wild fox squirrels (Sciurus niger).

Distress or alarm calls are vocalizations made when animals are in stressful situations or faced with a predator. Squirrels (Sciuridae) are known for being very vocal; however, most studies on alarm vocalizations are limited to ground squirrels. We investigated the acoustic behavior of the arboreal fox squirrel (Sciurus niger) under different conditions.

Acoustic behavior in the northern short-tailed shrew (Blarina brevicauda): Ultrasonic click production in a novel environment.

Although echolocation is classically associated with bats and dolphins, many animals produce ultrasonic and/or click-like signals to potentially navigate their environment. Shrews (Soricidae) are thought to rely on ultrasonic signals for echo-orientation, producing both ultrasonic click-like signals and tonal twittering signals. Recently, the role of ultrasonic clicks in shrew echo-orientation has been questioned, as these clicks have been proposed to be artifacts of shrews moving throughout their environment.