Urban ecologist Dr. Kenji Sato investigated the impact of anthropogenic noise on the vocalizations of the Japanese bush warbler (*Horornis diphone*). Sato hypothesized that to overcome low-frequency traffic noise, urban warblers adjust their songs by shifting to higher minimum frequencies than their rural counterparts. However, Sato also proposed that this frequency adjustment is physically taxing, resulting in a trade-off where the songs of urban birds become shorter and structurally simpler. Which finding, if true, would most directly support Sato's hypothesis?
- AJapanese bush warblers exposed to short bursts of traffic noise in a laboratory setting temporarily stopped singing altogether, suggesting that the species lacks the physiological capacity to adapt to urban environments.
- BJapanese bush warblers in noisy urban territories were found to have lower reproductive success and higher stress levels than those in quiet rural territories, regardless of their song characteristics.
- Songs of Japanese bush warblers in high-traffic urban areas had higher minimum frequencies, shorter durations, and fewer distinct notes than songs of warblers in quiet rural habitats.Answer
- DMany different songbird species residing in metropolitan areas adjust their vocalizations in various ways, showing that vocal adaptation is a common response to city noise.
Answer
The finding that songs of Japanese bush warblers in high-traffic urban areas had higher minimum frequencies, shorter durations, and fewer distinct notes than songs of warblers in quiet rural habitats.
The correct answer provides direct evidence for the two key predictions of the hypothesis: that urban Japanese bush warblers sing at higher minimum frequencies, and that these adjusted songs are shorter and structurally simpler than those of their rural counterparts.
Step-by-Step Solution
Key Concept
Command of Evidence: Textual