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.

BatCount: A software program to count moving animals.

One of the biggest challenges with species conservation is collecting accurate and efficient information on population sizes, especially from species that are difficult to count. Bats worldwide are declining due to disease, habitat destruction, and climate change, and many species lack reliable population information to guide management decisions. Current approaches for estimating population sizes of bats in densely occupied colonies are time-intensive, may negatively impact the population due to disturbance, and/or have low accuracy.

Variations in advertisement call modulations do not influence vocal interactions in bullfrog choruses.

Chorusing male bullfrogs naturally vary the number of modulations within their advertisement call notes. A field playback experiment investigated whether these variations affect males' evoked vocal responses. Vocal responses were quantified manually and automatically by quantifying acoustic energy.

Raptors avoid the confusion effect by targeting fixed points in dense aerial prey aggregations.

Collective behaviours are widely assumed to confuse predators, but empirical support for a confusion effect is often lacking, and its importance must depend on the predator's targeting mechanism. Here we show that Swainson's Hawks Buteo swainsoni and other raptors attacking swarming Mexican Free-tailed Bats Tadarida brasiliensis steer by turning towards a fixed point in space within the swarm, rather than by using closed-loop pursuit of any one individual. Any prey with which the predator is on a collision course will appear to remain on a constant bearing, so target selection emerges naturally from the geometry of a collision.

Estimating chorusing activity by quantifying total acoustic energy.

Passive acoustics provides a powerful method for localizing vocalizing animals and estimating species abundance. A passive acoustics method previously used to census dense populations of flying bats is applied here to estimate chorusing activity of male bullfrogs vocalizing against anthropogenic noise. There are significant links between manual counts of the numbers of advertisement call notes and automatically detected notes and two measures of acoustic energy.

Foundations of form and function: A synthesis-based curriculum for introductory-level organismal biology.

First-year majors organismal biology courses are frequently taught as survey courses that promote memorization rather than synthesis of biological concepts. To address the shortcomings of this approach, we redesigned the organismal portion of our introductory biology curriculum to create a "Foundations of Form and Function" course. Foundations of Form and Function introduces different organismal forms and focuses on the relationship between those forms and the execution of key physiological functions.

Aerial attack strategies of hawks hunting bats, and the adaptive benefits of swarming.

Aggregation can reduce an individual's predation risk, by decreasing predator hunting efficiency or displacing predation onto others. Here, we explore how the behaviors of predator and prey influence catch success and predation risk in Swainson's hawks attacking swarming Brazilian free-tailed bats on emergence. Lone bats including stragglers have a high relative risk of predation, representing ~5% of the catch but ~0.

Separation of overlapping sources in bioacoustic mixtures.

Source separation is an important step to study signals that are not easy or possible to record individually. Common methods such as deep clustering, however, cannot be applied to signals of an unknown number of sources and/or signals that overlap in time and/or frequency-a common problem in bioacoustic recordings. This work presents an approach, using a supervised learning framework, to parse individual sources from a spectrogram of a mixture that contains a variable number of overlapping sources.

Echolocation while drinking: Pulse-timing strategies by high- and low-frequency FM bats.

During nightly foraging activity, echolocating bats drink by flying low over the water surface and dipping the lower jaw while avoiding further bodily contact with the water. This task poses different sensorimotor challenges than flying in the open to forage for insects. Of interest is how bats adjust the timing of their echolocation pulses to accommodate the surrounding scene, from the progressively nearer water surface itself to objects at longer distances.

The effect of jamming stimuli on the echolocation behavior of the bottlenose dolphin, Tursiops truncatus.

Echolocating bats and odontocetes face the potential challenge of acoustic interference from neighbors, or sonar jamming. To counter this, many bat species have adapted jamming avoidance strategies to improve signal detection, but any such avoidance strategies in dolphins is unknown. This study provides an investigation into whether dolphins modify echolocation behavior during jamming scenarios.

Filibacter tadaridae sp. nov., isolated from within a guano pile from a colony of Mexican free-tailed bats Tadarida brasiliensis.

A Gram-stain-positive, aerobic bacterium, TB-66, was isolated from a pile of bat guano in a cave of New Mexico, USA. On the basis of 16S rRNA gene sequence similarity comparisons, strain TB-66grouped together with Filibacter limicola showing a 16S rRNA gene sequence similarity of 98.5 % to the type strain.

Echolocation adaptations during high-speed roost re-entry for Brazilian free-tailed bats (Tadarida brasiliensis).

Some bats re-enter their cave while using echolocation at very high speeds, but this behavior is poorly studied. Thermal imaging and an array of ultrasonic microphones were used to investigate the acoustic adaptations made during high-speed re-entry for single bats entering a cave. There was a significant overall effect between bat, distance to the ground, and its flight speed on pulse duration and interpulse interval (IPI).

Variation in Bat Guano Bacterial Community Composition With Depth.

Bats are known to be reservoirs for a variety of mammalian pathogens, including viruses, fungi, and bacteria. Many of the studies examining the microbial community inhabiting bats have investigated bacterial taxa found within specific bat tissues and isolated bat guano pellets, but relatively few studies have explored bacterial diversity within bat guano piles. In large bat caves, bat guano can accumulate over time, creating piles several meters deep and forming complex interactions with coprophagous organisms in a habitat with low light and oxygen.

Recording animal vocalizations from a UAV: bat echolocation during roost re-entry.

Unmanned aerial vehicles (UAVs) are rising in popularity for wildlife monitoring, but direct recordings of animal vocalizations have not yet been accomplished, likely due to the noise generated by the UAV. Echolocating bats, especially Tadarida brasiliensis, are good candidates for UAV recording due to their high-speed, high-altitude flight. Here, we use a UAV to record the signals of bats during morning roost re-entry.

A systematic method for isolating, tracking and discriminating time-frequency components of bat echolocation calls.

Echolocating bats can rapidly modify frequency modulation (FM) curvatures of their calls when facing challenging echolocation tasks. Frequency parameters, such as start/end/peak frequency, have often been extracted from the time-frequency domain to study the call variation. Even though this kind of signal investigation method reveals important findings, these approaches to analyze bat echolocation calls use bulk parameters, which hide subtleties in the call structure that may be important to the bat.

Off-axis targets maximize bearing Fisher Information in broadband active sonar.

Broadband active sonar systems estimate range from time delay and velocity from Doppler shift. Relatively little attention has been paid to how the received echo spectrum encodes information about the bearing of an object. This letter derives the bearing Fisher Information encoded in the frequency dependent transmitter beampattern.

Estimating colony sizes of emerging bats using acoustic recordings.

The decline of bats demands more widespread monitoring of populations for conservation and management. Current censusing methods are either prone to bias or require costly equipment. Here, we report a new method using passive acoustics to determine bat count census from overall acoustic amplitude of the emerging bat stream.

Transmission beam characteristics of a Risso's dolphin (Grampus griseus).

The echolocation system of the Risso's dolphin (Grampus griseus) remains poorly studied compared to other odontocete species. In this study, echolocation signals were recorded from a stationary Risso's dolphin with an array of 16 hydrophones and the two-dimensional beam shape was explored using frequency-dependent amplitude plots. Click source parameters were similar to those already described for this species.

Support for the beam focusing hypothesis in the false killer whale.

The odontocete sound production system is complex and composed of tissues, air sacs and a fatty melon. Previous studies suggested that the emitted sonar beam might be actively focused, narrowing depending on target distance. In this study, we further tested this beam focusing hypothesis in a false killer whale.

Mouth gape angle has little effect on the transmitted signals of big brown bats (Eptesicus fuscus).

Bats perform high-resolution echolocation by comparing temporal and spectral features of their transmitted pulses to the received echoes. In complex environments with moving prey, dynamically adapting the transmitted pulses can increase the probability of successful target representation and interception. This study further investigates the adaptive vocal-motor strategies of big brown bats (Eptesicus fuscus).

Cognitive adaptation of sonar gain control in the bottlenose dolphin.

Echolocating animals adjust the transmit intensity and receive sensitivity of their sonar in order to regulate the sensation level of their echoes; this process is often termed automatic gain control. Gain control is considered not to be under the animal's cognitive control, but previous investigations studied animals ensonifying targets or hydrophone arrays at predictable distances. To test whether animals maintain gain control at a fixed level in uncertain conditions, we measured changes in signal intensity for a bottlenose dolphin (Tursiops truncatus) detecting a target at three target distances (2.

High resolution acoustic measurement system and beam pattern reconstruction method for bat echolocation emissions.

Measurements of the transmit beam patterns emitted by echolocating bats have previously been limited to cross-sectional planes or averaged over multiple signals using sparse microphone arrays. To date, no high-resolution measurements of individual bat transmit beams have been reported in the literature. Recent studies indicate that bats may change the time-frequency structure of their calls depending on the task, and suggest that their beam patterns are more dynamic than previously thought.