02337nas a2200217 4500008004100000245008600041210006900127520164500196653002401841653000901865653002201874653002701896653002001923653001801943100001701961700001601978700002101994700002102015700002102036856006202057 2019 eng d00aDoes bat response to traffic noise support the misleading cue hypothesis?Abstract0 aDoes bat response to traffic noise support the misleading cue hy3 a

The world has become a noisier place due to the increase in urbanization. Noise is generally considered an impediment, altering an animal’s behavior through masking or distraction. But noise can also provide useful information about the environment. For animals that rely on natural environmental noise as an indicator of favorable foraging conditions, increasing levels of anthropogenic noise might mislead informed decision-making. Bats use rain noise, a natural environmental cue, to delay their emergence from the roost, presumably to avoid sensory and metabolic costs associated with foraging in heavy rain. Here we tested the “misleading cue hypothesis,” asking whether traffic noise is mistaken for rain noise by bats. Given the acoustic similarity between rain noise and traffic noise, we predicted that bats would confuse the two. We conducted a playback experiment using rain, traffic, and ambient noise at natural roosts of common big-eared bats (Micronycteris microtis, Phyllostomidae) and recorded bat emergence behavior. In contrast to their response to rain noise, the bats did not delay roost emergence in response to traffic noise. Thus, we found that bats were able to discriminate between traffic noise and rain noise and were not misled by similarity in acoustic parameters in the two noise types, when emerging from their roost. Emerging bats did show more exploration flights during traffic noise than during rain noise, but not during ambient noise, suggesting that they perceive traffic noise as a novel acoustic cue. Our data provide new insights into perception of traffic noise by bats.

10aanthropogenic noise10abats10aevolutionary trap10aMicronycteris microtis10amisleading cues10aTraffic noise1 aGeipel, Inga1 aAmin, Bawan1 aPage, Rachel, A.1 aHalfwerk, Wouter1 aCandolin, Ulrika uhttps://academic.oup.com/beheco/article/30/6/1775/557481102446nas a2200205 4500008004100000245007100041210006900112520175400181653002401935653002401959653002601983653002402009653001102033653001902044100002602063700002202089700002202111700002102133856008602154 2019 eng d00aExperience modulates an insect’s response to anthropogenic noise0 aExperience modulates an insect s response to anthropogenic noise3 a

In response to anthropogenic noise, vertebrates express modified acoustic communication signals either through individual plasticity or local population adaptation. In contrast, how insects respond to this stressor is poorly studied. Field crickets Gryllus bimaculatus use acoustic signals to attract and locate mates and are commonly found in noisy roadside environments, offering a powerful system to study the effects of anthropogenic noise on insect communication. Rapid repetition of sexual calls (chirps) is essential to attract females, but calling incurs energetic costs and attracts predators. As a result, males are predicted to reduce calling rates when background noise is high. Here, we combine observations and experimental playbacks to show that the responses of field cricket males to anthropogenic noise also depend on their previous experience with passing cars. First, we show that males living on highway edges decrease their chirp rate in response to passing cars. To assess whether this behavioral response depends on previous exposure to car noise, we then broadcast recordings of car noise to males located at different distances from the road and, therefore, with different previous exposure to car noise. Although all tested individuals responded to broadcasted traffic noise, males closest to the road decreased their chirp rate less than individuals calling further from the road. These results suggest that regular exposure to anthropogenic noise may decrease individuals’ sensitivity and behavioral responses to noise, allowing them to maintain effective signaling rates. Behavioral plasticity modulated by experience may thus allow some insect species to cope with human-induced environmental stressors.

10aacoustic adaptation10aanthropogenic noise10abehavioral plasticity10aGryllus bimaculatus10aInsect10asexual signals1 aGallego-Abenza, Mario1 aMathevon, Nicolas1 aWheatcroft, David1 aCandolin, Ulrika uhttps://academic.oup.com/beheco/advance-article/doi/10.1093/beheco/arz159/557470302270nas a2200241 4500008004100000022001400041245008000055210006900135260001600204520148200220653002401702653001301726653002301739653002101762653001701783653002201800100002101822700002701843700002901870700002201899700002101921856008601942 2019 eng d a1045-224900aEvidence for differing trajectories of songs in urban and rural populations0 aEvidence for differing trajectories of songs in urban and rural  cJul-08-20203 a

Learned traits, such as foraging strategies and communication signals, can change over time via cultural evolution. Using historical recordings, we investigate the cultural evolution of birdsong over nearly a 50-year period. Specifically, we examine the parts of white-crowned sparrow (Zonotrichia leucophrys nuttalli) songs used for mate attraction and territorial defense. We compared historical (early 1970s) recordings with contemporary (mid-2010s) recordings from populations within and near San Francisco, CA and assessed the vocal performance of these songs. Because birds exposed to anthropogenic noise tend to sing at higher minimum frequencies with narrower frequency bandwidths, potentially reducing one measure of song performance, we hypothesized that other song features, such as syllable complexity, might be exaggerated, as an alternative means to display performance capabilities. We found that vocal performance increased between historical and contemporary songs, with a larger effect size for urban songs, and that syllable complexity, measured as the number of frequency modulations per syllable, was historically low for urban males but increased significantly in urban songs. We interpret these results as evidence for males increasing song complexity and trilled performance over time in urban habitats, despite performance constraints from urban noise, and suggest a new line of inquiry into how environments alter vocal performance over time.

10aanthropogenic noise10abirdsong10aCultural evolution10asexual selection10aUrbanization10avocal performance1 aMoseley, Dana, L1 aPhillips, Jennifer, N.1 aDerryberry, Elizabeth, P1 aLuther, David, A.1 aCandolin, Ulrika uhttps://academic.oup.com/beheco/advance-article/doi/10.1093/beheco/arz142/5551107