This might seem like a bit of just deserts for all the times people have been woken up early by chirping birds, but human noise pollution is actually making it impossible for birds to mate. Humanity has crossed the line!
Yes, as far as birds are concerned, humans have pretty much become the inconsiderate roommate from hell, blasting heavy metal at all hours of the night while the birds are trying to get in the mood for a little romance. (We could probably extend the metaphor by equating not doing the dishes to all the crap that we dump in rivers or something, but let's keep this simple.) The noise we make isn't necessarily the most obvious way we impact the environment - and it definitely isn't one of the most closely studied - but it's having a serious impact on bird reproduction.
That's the finding of a new study by researchers from the University of Colorado and Fort Lewis College. In their paper, they explain why the dangers of noise pollution:
Human-generated noise pollution now permeates natural habitats worldwide, presenting evolutionarily novel acoustic conditions unprecedented to most landscapes. These acoustics not only harm humans, but threaten wildlife, and especially birds, via changes to species densities, foraging behavior, reproductive success, and predator-prey interactions. Explanations for negative effects of noise on birds include disruption of acoustic communication through energetic masking, potentially forcing species that rely upon acoustic communication to abandon otherwise suitable areas.
In particular, they found that larger birds often have to flee noisy areas, even if it's a traditional habitat, while smaller birds were able to remain and deal with the din. As they explain, it's all a question of whether their calls are the right frequency to be heard above the noise:
ignal duration and urban tolerance failed to explain species-specific responses, but birds with low-frequency signals that are more susceptible to masking from noise avoided noisy areas and birds with higher frequency vocalizations remained. Signal frequency was also negatively correlated with body mass, suggesting that larger birds may be more sensitive to noise due to the link between body size and vocal frequency...Larger birds with lower frequency signals may be excluded from noisy areas, whereas smaller species persist via transmission of higher frequency signals.
I'm not sure what the actual solution to this is, but I feel like we should maybe club together and buy the birds a bunch of noise-canceling headphones. Just seems like the thing a decent roommate would do.