Humans are the greatest ecosystem engineers. We’ve already altered most of the world’s land surface through mining, agriculture and urban development; we’ve modified marine ecosystems through introduced species, commercial fishing and shipping infrastructure; chemical pollutants from our greywater entering waterways are creating inter-sex fish; and light pollution from our cities, and even from ski-runs, is altering behaviour, reproduction and circadian rhythms of resident wildlife.
Now even the mere sound of our existence is reworking Nature. Noise pollution from development, airports, mining, and road traffic has always been an issue, not just as an annoyance to our own communities, but as a threat to nearby wildlife. Animals and birds can abandon their habitats through fright, or be driven out because the human-made noise makes it too difficult for them to find food or mates. Many birds and even whales have been forced to change the volume, sound frequency or timing of their calls to ensure they are heard above the din of human existence.
This issue has now gone to a whole new level. Some bird species that use mimic calls to attract mates have expanded their repertoire to include purely anthropogenic sounds. In Britain, blackbirds are being heard singing like ambulance sirens, cell phones, car alarms and even a reversing golf cart.
Ecologists studying the phenomenon think that it’s a reproductive strategy—female blackbirds prefer older men, so a male blackbird can prove his maturity by having a large song repertoire. Over time, this simple, localized change in behavior could have interesting repercussions for population dynamics and speciation.
What goes around comes around—humans have been directly responsible for numerous species extinctions in the past, and now we could be becoming the catalyst for the evolution of new ones.
© Manu Saunders 2010