@article {58311, title = {Does the presence of an observer affect a bird{\textquoteright}s occurrence rate or singing rate during a point count?}, year = {2020}, abstract = {

The approach or presence of an observer may affect the behavior of nearby birds, rendering them either more or less detectable than when no observer is present due to a change in singing rates. To test whether there are systematic detection biases associated with the presence of an observer during point count bird surveys, we compared the occurrence and singing rates of birds during a 10-min period immediately preceding the time when an observer arrived to conduct a count and during the formal count itself by extracting song information from autonomous sound recorders. We obtained recordings of 36 species of birds detected at \≥5 locations in one of three vegetation types, including burned conifer forest, green conifer/riparian streamside forest, and riparian bottomland/marshland. We found that species richness and both the probability of occurrence and singing rate for any of the species recorded were unaffected by the presence of an observer. In addition, the probability of occurrence did not differ significantly among four 2.5-min recording sessions during 10-min counts when an observer was present. Thus, the presence of an observer did not appear to introduce any detectable systematic bias that would make bird lists or unadjusted occurrence rates inaccurate on that basis alone. In addition, rates of bird occurrence across 2.5-min temporal subsets of a 10-min count did not vary in a systematic way that would violate the assumption of equal occupancy across adjacent time periods as sometimes used to build detection histories in occupancy modeling.

}, keywords = {bird survey, detectability, observer effect, occupancy, passive acousticsampling, point count, singing rate, utonomous recording unit}, doi = {10.1111/jofo.12329}, url = {http://doi.wiley.com/10.1111/jofo.12329}, author = {Hutto, Richard L. and Hutto, Russell R.} } @article {53368, title = {Ravens adjust their antipredatory responses to con- and hetero-specific alarms to the perceived threat}, journal = {Ethology}, volume = {124}, year = {2018}, month = {Jan-08-2018}, pages = {609 - 616}, abstract = {

Heterospecific alarm calls are typically found in situations where multiple species have a common predator. In birds, they are particularly common in mixed mixed-species flocks. In species with highly developed social and cognitive abilities like corvids, there is the potential for differential responses to heterospecific vs. conspecific calls according to the riskiness of the habitat. We tested the responses of free-ranging ravens (Corvus corax) to conspecific alarm calls and compared them to heterospecific alarm calls of jackdaws (Corvus monedula). We observed the proportion of ravens leaving the feeding site after the con- or hetero-specific playback was presented in a situation of low threat (wild boar\—Sus scrofa enclosure) and high threat of predation (wolf\—Canis lupus enclosure). We show that ravens responded to conspecific calls more intensively at the wolves than at the wild boar, but the response to conspecific calls was in both enclosures stronger than to the control (great tit\—Parus major song). The response to the heterospecific alarm was also stronger in the wolves\’ enclosure, but it did not differ from control in the wild boar enclosure. These findings suggest that ravens are aware of the meaning of the jackdaw alarm calls, but they respond to it only in a situation of high predatory threat (wolves are present). In the wild boar enclosure, the ravens probably consider jackdaws warning against some other predator, very probably harmless to ravens. This interpretation requires further testing, as both enclosures differ also in respect to other parameters like food quality and shelter availability.

}, keywords = {avoidance, corvid, honest signal, jackdaw, predator, threat}, doi = {10.1111/eth.2018.124.issue-810.1111/eth.12764}, url = {http://doi.wiley.com/10.1111/eth.2018.124.issue-8}, author = {N{\'a}carov{\'a}, Jana and Vesel{\'y}, Petr and Bugnyar, Thomas}, editor = {Tregenza, T.} } @article {47717, title = {On-Bird Sound Recordings: Automatic Acoustic Recognition of Activities and Contexts}, journal = {IEEE/ACM Transactions on Audio, Speech, and Language Processing}, volume = {25}, year = {2017}, month = {Jan-06-2017}, pages = {1193 - 1206}, abstract = {

We introduce a novel approach to studying animal behavior and the context in which it occurs, through the use of microphone backpacks carried on the backs of individual free-flying birds. These sensors are increasingly used by animal behavior researchers to study individual vocalizations of freely behaving animals, even in the field. However, such devices may record more than an animal\&$\#$39;s vocal behavior, and have the potential to be used for investigating specific activities (movement) and context (background) within which vocalizations occur. To facilitate this approach, we investigate the automatic annotation of such recordings through two different sound scene analysis paradigms: A scene-classification method using feature learning, and an event-detection method using probabilistic latent component analysis. We analyze recordings made with Eurasian jackdaws (Corvus monedula) in both captive and field settings. Results are comparable with the state of the art in sound scene analysis; we find that the current recognition quality level enables scalable automatic annotation of audio logger data, given partial annotation, but also find that individual differences between animals and/or their backpacks limit the generalization from one individual to another. we consider the interrelation of \“scenes\” and \“events\” in this particular task, and issues of temporal resolution.

}, keywords = {acoustics, birds, context, event detection, image analysis, microphones, pattern recognition, speech, zoology}, issn = {2329-9290}, doi = {10.1109/TASLP.2017.2690565}, url = {http://ieeexplore.ieee.org/document/7933044/}, author = {Stowell, Dan and Gill, Lisa F.} }