A team of ecologists hypothesizes that some songbirds adjust their song pitch in cities specifically to overcome low-frequency traffic noise, rather than as a side effect of general urban stress or differences in singing behavior across populations.
Which finding, if true, would most strongly support the team's hypothesis?
- A
Many city songbirds have stable populations.
- Bcheck_circle
Within the same city, individual birds shifted their songs to higher pitches at noisy roadside territories than at quieter park territories, but produced similar song lengths and rates in both.
- C
Birds in cities sometimes sing earlier in the day than rural counterparts.
- D
Some bird species are more vocal than others.
Explanation
A holds song length, rate, and population identity constant, showing pitch shifts depend on local noise — directly supporting the targeted-adaptation hypothesis. B, C, and D are tangential.