November 30th, 2012 by

Though originating on different sides of the Atlantic, two studies released this month both underscore the complexities of wildlife adaptation to the urbanization of their habitats.

Vermilion flycatcher

Vermilion flycatcher.

I’m sure I’m not the only one who sometimes sets my alarm clock’s ring tone to “birdsong” for a soothing start to the day. But birdsong is much more than calming and beautiful sounds. Songbirds sing to attract mates, to define their territory and even to defend themselves against threats. But what about urban songbirds? How do they compete with the noise of the city?

Previous studies have shown different frequencies between urban birdsong and birdsong in the wild, but until recently, no study had looked at the tropical cousins of these songbirds. Now, Alejandro Ariel Ríos-Chelén and fellow researchers at the Universidad Nacional Autonoma de Mexico have published a study that does just that.

The researchers recorded the songs of 29 male vermilion flycatchers in Mexico City and found that birds in noisier locations consistently sang for longer, assuring their song could be heard among the noise pollution. The differences between how these flycatchers’ adapted their songs for the urban environment and the adaptations that had been observed in other species suggests that different species have different methods of coping with noise pollution. Some species may be better equipped to adapt than others.

Common redshank

Common redshank. Credit: Srihari Kulkarni/Flickr

Meanwhile, findings of a study released Tuesday on the affects of light pollution on the common redshank in the Forth estuary in Scotland suggest a similar lesson. Dr. Ross Dwyer of the University of Exeter led the study, in which 20 birds were tagged to track their location, while inbuilt posture sensors told scientists when the birds bent to forage food. The study found that in areas with less artificial light, birds switched between foraging by sight and foraging by touch. In contrast, birds foraging closer to the massive petrochemical complex that lights up parts of the estuary were able to rely on sight regardless of moonlight or cloud cover. Needless to say, these birds had a more satisfying dinner.

Both studies show that some species are adapting — even thriving, in the case of the redshank — to various types of pollution that come with increasing urbanization of their habitats. It remains to be seen, however, how these species will adapt in the long term, particularly as other species they rely on suffer adverse effects. One thing is certain, though. As urban areas increase, more and more wildlife will strive to adjust. We can help them by making sure our city and infrastructure planning include consideration for urban forests and urban wildlife.