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/30/6/1775/557481102262nas a2200205 4500008004100000022001400041245009600055210006900151260001600220520156100236653001701797653002101814653002701835653002701862653002101889100002201910700001701932700002101949856008601970 2019 eng d a1045-224900aEnvironmental constraints on size-dependent signaling affects mating and rival interactions0 aEnvironmental constraints on sizedependent signaling affects mat cMar-02-20203 a

Advertisement signals can convey information about a sender’s characteristics, such as body size. The reliability of signals, however, can be reduced when signal production is partially dependent on the environment. Here, we assess the effect of display-site properties on the production, attractiveness and honesty of sexual signals. We recorded male túngara frogs (Physalaemus pustulosus) while manipulating water levels in order to constrain calling. We found that water level affected male call properties in a size-dependent manner, with call amplitude being less affected in smaller males when forced to call in shallow water. Next, we tested how size-dependent and display-site-dependent signaling affected female choice and rival competition. Both males and females showed the strongest response to the call of a large male when he was calling at the deepest water levels. However, females showed no preference for large over small males when both were recorded in shallow water levels, or, depending on the call rate and timing of calls, even preferred small males. Likewise, males responded equally to large and small rivals recorded calling during shallow water level trials. Our experiments show that display-site properties can influence signal production and attractiveness in a size-dependent manner. These results can have important consequences for the evolution of signaling, as small males may be able to use their size to their advantage when selecting appropriate display sites and thereby outcompete large males.

10adisplay site10ahonest signaling10aPhysalaemus pustulosus10aproduction constraints10asexual selection1 aSmit, Judith, A H1 aLoning, Hugo1 aHalfwerk, Wouter uhttps://academic.oup.com/beheco/advance-article/doi/10.1093/beheco/arz009/532052302274nas a2200241 4500008004100000022001400041245009400055210006900149260001600218300001500234520143200249653000901681653002001690653001301710653002101723653001001744653000901754100001701763700002401780700002101804700002101825856018601846 2019 eng d a0022-094900aNoise as an informational cue for decision-making: the sound of rain delays bat emergence0 aNoise as an informational cue for decisionmaking the sound of ra cSep-01-2020 ajeb.1920053 a

Background noise can have strong negative consequences on animals, reducing individual fitness by masking communication signals, impeding prey detection and increasing predation risk. While the negative impacts of noise across taxa have been well documented, the use of noise as an informational cue, providing animals with reliable information on environmental conditions has been less well studied. In the tropical rainforest, downpours can be intense and frequent. Strong rainfall may impede efficient orientation and foraging for bats that need echolocation to both navigate and detect prey, and can result in higher flight costs due to increased metabolic rates. Using playback experiments at natural roosts we tested whether two bat species, differing in their hunting strategies and foraging habitats, use rain noise as a cue to delay emergence from their roosts. We found that both species significantly delayed their emergence time during rain noise playbacks compared to silence and ambient noise controls. We conclude that bats can use background noise, here the acoustic component of rainfall, as a reliable informational cue to make informed decisions, here about whether to initiate foraging trips or remain in the shelter of their roosts. Our findings suggest that environmental background noise can sometimes be beneficial to animals, in particular in situations where other sensory cues may be absent.

10abats10adecision-making10aforaging10ainformation cues10aNoise10arain1 aGeipel, Inga1 aSmeekes, Marcus, J.1 aHalfwerk, Wouter1 aPage, Rachel, A. uhttp://jeb.biologists.org/lookup/doi/10.1242/jeb.192005https://syndication.highwire.org/content/doi/10.1242/jeb.192005https://syndication.highwire.org/content/doi/10.1242/jeb.192005