| Recent research has established that anthropogenic noise affects bird song structure due to behavioral adjustments, but does natural background noise affect song structure in the same way? As anthropogenic noise increases in urban environments, a number of species of birds will increase the minimum frequency of their songs and therefore reduce the frequency bandwidth. This is relevant because it has been shown that there is a performance frontier in relation to song bandwidth and trill rate. Reduction in bandwidth reduces performance value which results in lower responsiveness to adjusted songs and reduced mating opportunities (Luther, Phillips and Derryberry, 2015) Our study investigates the relationship between amplitude of ocean noise on White-crowned Sparrow song structure, focusing on the trill, and vocal performance in Montaña de Oro State Park, on the Central Coast of California. Individuals in areas with higher amplitudes of ocean noise have a higher minimum trill frequency and a reduced trill bandwidth. Our results suggest that White-crowned Sparrows are behaviorally adjusting their songs in response to natural background noise similarly to urban birds and may face the same challenges such as having fewer mating opportunities. |