How our cities impact birds

A bustling metropolis can barely be considered a refuge for wildlife, but studies show nearly a fifth of all birds in the world thrive in our cities. With scanty tree cover, sky-high concrete structures, earsplitting noise and blinding lights, how do birds make sense of and live in our cities? Turns out, over the years, aves with ‘urban traits’ have been evolutionarily selected to live in our cities, and these birds have also adapted in unique ways to survive and thrive.

For instance, urban bird species don’t forage over large areas as it increases the risk of getting hit by a vehicle or a building. They also tend to have smaller eyes than their rural counterparts to deal with dazzling city lights. Artificial light pollution can disorient birds as they fly and increase their chances of colliding with buildings. This phenomenon kills nearly one billion birds annually in the US and Canada. 

The incessant low-frequency noise in our cities is drowning out bird calls and songs, disrupting their mating and feeding behaviour. To cope with the dinn and be heard, city birds are singing faster, at higher frequencies and for longer periods—a feat that drains energy from their tiny bodies. Some birds, like the white-crowned sparrows of San Francisco Bay, have changed their tune altogether to be heard. Unhatched zebra finches and hatchlings show stunted growth when exposed to noise pollution, which can impact their long-term population. 

City diets for birds, mostly including seeds and fewer fruits, also influence how birds look. The bright colours in bird feathers come from carotenoids—fat-soluble pigments that give colour to plant parts like fruits. However, in cities, birds rely on seeds or junk foods high in sugar and low in nutrition. Besides, they are exposed to heavy metals like cadmium and lead. As a result, they develop duller plumage—a phenomenon scientists call ‘urban dullness.’

As India’s bird species show a staggering 60% decline, it’s time to look at how our cities contribute to the crisis and redesign them to accommodate us and our feathered friends.