02093nas a2200157 4500008004100000245013800041210006900179520149100248653002601739653001301765653003201778653001301810653001001823100003101833856007101864 2021 eng d00aUse of simple graded signals in the long-distance vocal communication of a forest thrush ( Catharus fuscescens )0 aUse of simple graded signals in the longdistance vocal communica3 a

I investigated the use of simple graded structures (i.e. ‘calls’) in long-distance vocal communication among territorial forest-dwelling Catharus fuscescens – an oscine passerine that also possesses a complex song. Two experiments were conducted: (1) Nests were threatened in three different contexts to test the effect of increasing motivation on three response variables (call form, rate, amplitude), and (2) a playback study was undertaken to quantify the accomplishments of graded call structures on territory-holders. Results from the two experiments showed that long-distance communication in the focal species is dependent on two concurrent aspects of communication: (1) Acoustic cues to signaller motivation via call rate, (2) spectral cues that reveal directivity – either precisely or imprecisely – that complement the perception of signaller location via distance assessment (ranging). Simultaneously, amplitude and bandwidth are adjusted to beam signals across various distance intervals. Therefore, to affect conspecific behaviour, a signaller can alter vocal cues to manipulate an assessor’s perception of signaller location while revealing motivation. This study reveals the foundational components of short and long-distance communication with the use of simple graded calls by a forest-dwelling oscine passerine. It is similar to long-distance communication networks documented in some parrots, marine mammals, and primates.

10aAssessment/Management10aCatharus10amotivation-structural rules10aSongbird10aVeery1 aHeckscher, Christopher, M. uhttps://www.tandfonline.com/doi/full/10.1080/09524622.2021.188831602273nas a2200205 4500008004100000245010700041210006900148520160100217653001601818653001801834653002001852653001401872653002901886653001601915653001701931653002901948100002301977700002302000856004402023 2020 eng d00aDoes the presence of an observer affect a bird's occurrence rate or singing rate during a point count?0 aDoes the presence of an observer affect a birds occurrence rate 3 a

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.

10abird survey10adetectability10aobserver effect10aoccupancy10apassive acousticsampling10apoint count10asinging rate10autonomous recording unit1 aHutto, Richard, L.1 aHutto, Russell, R. uhttp://doi.wiley.com/10.1111/jofo.1232902516nas a2200217 4500008004100000245010300041210006900144260001600213490000700229520180700236653002502043653002402068653001302092653001402105653002202119653001802141653001702159100002502176700002402201856007302225 2019 eng d00aHabitat-related differences in song structure and complexity in a songbird with a large repertoire0 aHabitatrelated differences in song structure and complexity in a cJan-12-20190 v193 a

Background

Urbanisation has been shown to influence many aspects of animal vocal communication. Much attention has been paid to anthropogenic noise, which is often described as one of the most challenging disturbances for urban dwellers. While a large body of literature describes associations between vocal behavior of avian populations and background noise level, most of these studies were conducted on species with relatively simple songs and small repertoire sizes. This study focuses on the song thrush, Turdus philomelos, a common Eurasian songbird with a complex singing style and large syllable repertoire. Our objective was to determine whether frequency, repertoire and temporal organisation of song parameters vary between birds inhabiting urban and adjacent forest habitats in which ambient noise levels differ.

Results

Songs of urban males were found to be more complex than in conspecifics from natural forest populations. Urban dwellers possessed greater syllable repertoires and repeated syllable sequences more often. In addition, they used a smaller proportion of whistles and a higher proportion of twitter syllables when singing compared to the nonurban males. Moreover, we found significant differences in the minimum and peak frequency of the whistle syllable between studied populations.

Conclusions

These findings may be an example of adaptation of acoustic communication in noisy urban environments, but we also discuss other possible explanations. We emphasize the need for further investigation into the relationships between birdsong and habitat characteristics, male quality, population density and ambient noise level in populations occupying urban and nonurban habitats.

10aanimal communication10aanthropogenic noise10abirdsong10asongbirds10aTurdus philomelos10aUrban ecology10aurbanisation1 aDeoniziak, Krzysztof1 aOsiejuk, Tomasz, S. uhttps://bmcecol.biomedcentral.com/articles/10.1186/s12898-019-0255-700949nas a2200241 4500008004100000022001300041245010600054210006900160260001600229300001200245490000800257653002100265653002400286653001600310653002300326653002100349100002500370700001900395700002000414700001800434700002200452856023300474 2018 eng d a0003347200aA new statistical method to test equivalence: an application in male and female eastern bluebird song0 anew statistical method to test equivalence an application in mal cJan-11-2018 a77 - 850 v14510aeastern bluebird10aequivalence testing10afemale song10ahypothesis testing10apublication bias1 aRose, Evangeline, M.1 aMathew, Thomas1 aCoss, Derek, A.1 aLohr, Bernard1 aOmland, Kevin, E. uhttps://linkinghub.elsevier.com/retrieve/pii/S0003347218302744https://api.elsevier.com/content/article/PII:S0003347218302744?httpAccept=text/xmlhttps://api.elsevier.com/content/article/PII:S0003347218302744?httpAccept=text/plain02160nas a2200145 4500008004100000245011200041210006900153260002000222300001100242490000600253520167400259100002301933700001701956856004101973 2017 eng d00aVocalizing during gaps in anthropogenic noise is an uncommon trait for enhancing communication in songbirds0 aVocalizing during gaps in anthropogenic noise is an uncommon tra cJul-06-20172238 aTLP16D0 v13 a

Mounting evidence suggests that anthropogenic noise negatively impacts many wildlife species, including songbirds. One mechanism by which noise affects songbirds may be through acoustic obstruction to their systems of vocal communication. However, many species increase the amplitude or pitch of their vocalizations, which may partially mitigate the impact of high noise levels. When the amplitude of anthropogenic noise varies over time, such as near a moderate-use highway, short gaps between noise events may also provide an important opportunity for communication. But, whether songbirds adjust vocalization rates rapidly to avoid overlap with noise is unknown for most species. We used acoustic playback to expose songbirds to simulated road noise during the dawn chorus in otherwise quiet habitats. We measured vocalization rates under ambient conditions and during quiet gaps embedded within playback of road noise to assess whether a community of songbirds, and nineteen individual species, vocalize more regularly during noise gaps. There were no significant differences in community-wide acoustic output. Species-specific analysis revealed that only four species altered their vocal rates during quiet gaps in noise, but that the direction of the effect varied by species. Point count results revealed that birds generally remained on site for the duration of the experiment, suggesting that abandonment of noisy locations was unlikely to confound our results. In sum, increasing vocal output during short gaps in noise occurred in only a handful of species, perhaps contributing to the limited number of species that are found within noisy habitats.

1 aProppe, Darren, S.1 aFinch, Emily uhttps://bio.acousti.ca/de/node/5259702887nas a2200181 4500008004100000245007200041210006900113260001600182300001400198490000800212520232400220100002602544700002202570700001902592700002402611700001502635856005502650 2017 eng d00aDo birds differentiate between white noise and deterministic chaos?0 aDo birds differentiate between white noise and deterministic cha cJan-12-2017 a966 - 9730 v1233 a

Noisy, unpredictable sounds are often present in the vocalizations of fearful and stressed animals across many taxa. A variety of structural characteristics, called nonlinear acoustic phenomena, that include subharmonics, rapid frequency modulations, and deterministic chaos are responsible for the harsh sound quality of these vocalizations. Exposure to nonlinear sound can elicit increased arousal in birds and mammals. Past experiments have used white noise to test for effects of deterministic chaos on perceivers. However, deterministic chaos differs structurally from white noise (i.e., random signal with equal energy at all frequencies), and unlike white noise, may differ dramatically depending on how it is produced. In addition, the subtle structural variation of chaos may not be distinguishable in the environment due to the attenuation and degradation of sound over distance and different habitat types. We designed two experiments to clarify whether American robins (Turdus migratorius) and warbling vireos (Vireo gilvus) discriminate between white noise and deterministic chaos. We broadcast and re-recorded white noise and two exemplars of deterministic chaos—one generated with a Chua oscillator and the other generated using a logistic equation—at 1, 10, 20, 30, 40, and 80 m across open and forested habitat and used spectrogram correlations to compare stimuli along this degradational gradient. We found that sounds degraded similarly in both habitats when compared to a reference distance of 1 m. Comparing pairs of stimuli across distances suggested that Chua chaos was more easily distinguishable from noise and logistic chaos. In addition, all stimuli became more distinctive over increased distance. The second experiment tested behavioral responses of robins and warbling vireos to control sounds of tropical kingbird (Quiscalus mexicanus), white noise, and two exemplars of deterministic chaos (Chua and logistic). Neither American robins nor warbling vireos responded differently to at least two types of deterministic chaos and white noise, validating previous playback studies that used white noise as a surrogate for deterministic chaos. Uniform responses to a variety of nonlinear features in these birds possibly reflect error management in alarm signal detection.

1 aBlumstein, Daniel, T.1 aWhitaker, Jessica1 aKennen, Judith1 aBryant, Gregory, A.1 aKoenig, W. uhttp://doi.wiley.com/10.1111/eth.2017.123.issue-1202338nas a2200253 4500008004100000022001300041245008700054210006900141260001600210300001400226490000800240520155900248653002401807653001801831653001401849653002201863653002301885653001101908653002801919100002801947700001901975700002401994856006602018 2017 eng d a0003347200aEavesdropping avoidance and sound propagation: the acoustic structure of soft song0 aEavesdropping avoidance and sound propagation the acoustic struc cJan-12-2017 a113 - 1210 v1343 aMany species use low-amplitude (soft) song during close range interactions with conspecifics, such as in aggressive encounters or courtship displays. It has been suggested that soft song is adapted to limit eavesdropping by conspecifics or predators through reduced signal transmission range. If so, other structural features of soft song, besides amplitude, should be adapted to reduce transmission. The soft songs of white-throated thrushes, Turdus assimilis, have properties expected to lower transmission, such as higher frequency and broader bandwidth relative to broadcast songs. We compared the transmission properties of broadcast and soft syllables using a sound propagation field experiment. When played at the same amplitude as broadcast song, soft song showed greater excess attenuation and blur ratios and lower signal-to-noise ratios. Lowering the frequency of soft syllables recovered similar transmission properties as those of broadcast syllables. Further analysis of spectral traits showed that excess attenuation values were mainly affected by minimum frequency and peak frequency, while blur ratio variation was predominantly affected by bandwidth, and signal-to-noise ratios were predicted by bandwidth and peak frequency. Additionally, soft song had more frequency overlap with background noise than broadcast song. These results support the eavesdropping hypothesis: aspects of the acoustic structure of soft signals in addition to low amplitude seem to have been shaped by selection to reduce transmission and avoid eavesdroppers.10acommunication range10asignal design10asong mode10asound degradation10asound transmission10aTurdus10awhispered communication1 aVargas-Castro, Luis, E.1 aSandoval, Luis1 aSearcy, William, A. uhttp://linkinghub.elsevier.com/retrieve/pii/S0003347217303329