Abstract
There is growing concern that anthropogenic noise could interfere with animal behaviours by masking the perception of acoustic communication signals. To date, however, few experimental studies have tested this general hypothesis. One common source of anthropogenic noise is the sound of roadway traffic. We tested the hypothesis that road traffic noise can mask a female's perception of male signals in the grey treefrog, Hyla chrysoscelis, by comparing the effects of traffic noise and the background noise of a breeding chorus on female responses to advertisement calls. In this species, advertisement calls are necessary and sufficient to attract females for breeding. Using a phonotaxis assay, we presented females with an advertisement call broadcast at one of nine signal levels (37-85 dB, 6-dB steps) in one of three masking conditions: (1) no masking noise, (2) a noise simulating a moderately dense breeding chorus, or (3) a noise modelled after road traffic noise recorded in two wetlands near major roads. Females showed similar increases in response latency and decreases in orientation towards the target signal in the presence of both the chorus noise and the traffic noise maskers. Moreover, response thresholds were elevated by about 20-25 dB in the presence of both noise maskers compared to the unmasked condition. Our results suggest that realistic levels of traffic noise could place constraints on the active space of the acoustic signals of some animals.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 1765-1776 |
| Number of pages | 12 |
| Journal | Animal Behaviour |
| Volume | 74 |
| Issue number | 6 |
| DOIs | |
| State | Published - Dec 2007 |
Bibliographical note
Funding Information:We thank John Moriarty and the Ramsey County Parks Department for access to the Tamarack Nature Center, Madeleine Linck and the Three Rivers Park District for access to the Carver Park Reserve, and Ed Quinn, Mark Crawford, and the Minnesota Department of Natural Resources for access to the Lake Maria State Park. Laura Cremin, Katie Grillaert, Melanie Harrington, Kasen Riemersma, and Sandra Tekmen provided helpful assistance with collecting and testing frogs. This work was approved by the University of Minnesota's IACUC (no. 0510A76966) on 15 December 2005, and complied with all laws of the U.S.A. Animal collections were carried out under Special Permit 13313 from the Minnesota Department of Natural Resources. This work was supported by a Grant-in-Aid from the Dean of the Graduate School of the University of Minnesota.
Keywords
- Hyla chrysoscelis
- acoustic communication
- anthropogenic noise
- auditory masking
- chorus noise
- grey treefrog
- traffic noise
- urban noise