Keep an ear out and you are likely to hear the songs of sparrows! Yes, that's how common they are. So familiar that we may ignore their existence. 

As one of the most common birds in our urban environment, sparrows have largely contributed to our day-to-day biodiversity. But maybe because they are not as rare nor noticeable as elephants and tigers, little attention has been given to them. 

Therefore, March 20 is marked as World Sparrow Day since 2010, to raise the awareness of sparrows and to encourage the public to appreciate the beauty of common biodiversity which is taken so much for granted.

So how much do you know about these little cute creatures around us? Take a test to see your score!

City life is abundant, but it poses lots of threats to sparrows. For example, modern architecture is difficult for birds to build nests. The pesticides used to keep plants healthy not only can poison the birds, but also kill insects which are the primary food for sparrows. Apart from this, electromagnetic radiation (EMR) is also a pollutant, which can cause a decrease in birds' population. 

So what can we do to help our petit friends adapt to a fast developing city? At an individual level, we can hang artificial bird nests in cities and prepare water and food for them. We can pay more attention to animals' needs and live a greener life. Plant more trees and live green. Even little efforts can make a difference!

For more stories about sparrows and how they were removed from the "four pests" list in China, you can check The man who saved sparrows from catastrophe

(All images via VCG)